Neutrophil counts distinguish between malignancy and arthritis in children with musculoskeletal pain: a case–control study

  • Antonella Agodi1,

    Affiliated with

    • Martina Barchitta1,

      Affiliated with

      • Cristina Trigilia2,

        Affiliated with

        • Patrizia Barone3,

          Affiliated with

          • Silvia Marino2,

            Affiliated with

            • Rosaria Garozzo3,

              Affiliated with

              • Manuela La Rosa1,

                Affiliated with

                • Giovanna Russo2 and

                  Affiliated with

                  • Andrea Di Cataldo2Email author

                    Affiliated with

                    BMC Pediatrics201313:15

                    DOI: 10.1186/1471-2431-13-15

                    Received: 13 September 2012

                    Accepted: 15 January 2013

                    Published: 31 January 2013

                    Abstract

                    Background

                    To identify the predictive factors for malignancies using basic clinical and laboratory information in children presenting with musculoskeletal pain and eventually diagnosed with juvenile idiopathic arthritis (JIA) or malignancy.

                    Methods

                    A retrospective case–control chart review research examining laboratory data from patients referred for musculoskeletal pain in 2001–2010 and diagnosed with malignancy or JIA was performed. The validity of each test for the diagnosis of neoplasia was assessed by calculating the sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and likelihood ratios.

                    Results

                    A total of 134 patients were enrolled. Statistically significant differences were found in neutrophil count, Hb, LDH, IgA and C4 values, ANA, anti-EA EBV IgG and anti-CMV IgG titres. High LDH value and anti-CMV IgG were the most predictive factors for neoplasia. High specificity factors for neoplasia were abnormal values of neutrophil count, Hb, IgA and C4, and the presence of anti-EA EBV and anti-CMV IgG. High PPV were recorded for abnormal neutrophil count, Hb value and anti-CMV titre. A low NPV was found only for anti-EA EBV and anti-CMV titres.

                    Conclusions

                    In this setting of patients, minimum changes in neutrophil count, particularly if associated with low Hb and high LDH levels, are to be thoroughly considered, because they appear as the most predictive factors for the diagnosis of tumour.

                    Keywords

                    ALL neuroblastoma Juvenile idiopathic arthritis Pediatric hematology/oncology Musculoskeletal pain White blood cell count

                    Background

                    Musculoskeletal pain is a common symptom in children, and in some cases it is the first sign of a severe disease such as chronic inflammatory disease or a malignancy [14]. About 15% to 30% of children with acute lymphoblastic leukaemia (ALL), the commonest childhood malignancy, and most patients with disseminated neuroblastoma report joint and/or bone symptoms [24]. In a child with leukaemia, musculoskeletal pain is normally accompanied by other clinical, laboratory and imaging data that easily indicate the diagnosis. Only in very few cases this sign is isolated, which complicates the diagnosis [2, 4]. On the other hand, in the absence of patognomonic tests the diagnosis of juvenile idiopathic arthritis (JIA) is the result of an integrative analysis of several data excluding other potential aetiologies of the pain and satisfying the established criteria [5]. Adult patients are able to guide the physician to the right diagnosis since they can thoroughly depict the characteristics of the pain. Conversely, a child can hardly describe it clearly.

                    In this particular setting, the insidious onset and the lack of typical signs and laboratory tests may delay malignancy diagnosis in children [5, 6]. Another risk is misdiagnosis, like JIA, and the consequent administration of corticosteroids leading to further delays and wrong treatments [6].

                    Literature data comparing children with malignancies to those with JIA for the pattern of initial findings is limited and involves small series of patients [79] and to translate results into optimal clinical practice is crucial: this is the reason why we undertook this retrospective analysis.

                    In order to improve the quality of clinical practice and patient outcomes, the aim of our study was to identify the predictive factors for malignancies using basic clinical and laboratory information in children presenting with musculoskeletal pain and eventually diagnosed with JIA or malignancy.

                    Methods

                    The study is a retrospective case–control chart review research examining both clinical and laboratory data from the initial visit of all the patients referred for musculoskeletal pain to the Department of Paediatrics of the University of Catania during the period January 2001–December 2010 and diagnosed with a neoplastic disease or JIA. We included patients with neoplasia and patients with JIA, already diagnosed, and retrospectively reviewed their charts in order to evaluate all relevant clinical and laboratory data. Patients with blast cells in the blood smear were excluded.

                    The study has been approved by the Institutional Review Board of our Department of Pediatrics.

                    Information regarding demographic data, symptoms, clinical manifestations, diagnosis, outcome and laboratory data were collected from the clinical records.

                    Statistical analyses were performed using the software SPSS version 14.0 (SPSS, Chicago, IL, USA). Percentage was used to describe categorical variables, while continuous variables were described by mean and range. Statistical comparison of proportions was performed by χ 2 test; statistical comparison of continuous variables was carried out by Student’s t-test. Basic significance level was fixed at p <0.05. The value of the given diagnostic test as a predictive factor for neoplasia in comparison to JIA and for ALL in comparison to JIA were assessed among groups, only for significantly different variables (p <0.05), by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive and negative likelihood ratios (LR+ and LR- respectively). In particular, for each diagnostic test, sensitivity was determined by calculating the proportion of the number of true positive patients among all patients with the disease (i.e. true positives and false negatives); specificity was determined by calculating the proportion of the number of true negative patients among all healthy patients (i.e. true negatives and false positives); PPV was determined by calculating the proportion of the number of true positive patients among all positive patients (i.e. true positives and false positives); NPV was determined by calculating the proportion of the number of true negative patients among all negative patients (i.e. true negatives and false negatives); the LR+ was computed as the sensitivity divided by 1–specificity and the LR- as 1–sensitivity divided by specificity. The differences in the denominators were the result of missing data for the variable analyzed.

                    Results

                    During the ten-year study a total of 150 patients hospitalised because of musculoskeletal pain were eventually diagnosed with JIA (n = 71) or malignancy (n = 79). Sixteen out of the 79 children with malignancy were excluded because blast cells were shown in the blood smear, so 134 patients (63 with malignancy and 71 with JIA) were finally enrolled in the study. Their main characteristics are shown in Table 1. ALL was the most frequent neoplasia type and oligoarticular JIA the most frequent JIA subtype. Age and gender distributions were similar in the two groups.
                    Table 1

                    Characteristics of patients with neoplasia and patients with JIA

                     

                    All patients (n= 134)

                    Neoplasia (n= 63)

                    JIA (n= 71)

                    Mean age in months (range)

                    92.2 (3–203)

                    92.6 (3–203)

                    91.9 (15–198)

                    Female

                    57.5%

                    52.4%

                    62.0%

                    Neoplasia types

                     - ALL

                     

                    47  74.6%

                     

                     - Lymphomas

                     

                    4     6.3%

                     

                     - Other neoplasia

                     

                    12  19.1%

                     

                    JIA subtypes

                     - systemic

                      

                    18 25.4%

                     - polyarthritis

                      

                    15 21.1%

                     - oligoarticular

                      

                    36 50.7%

                     - psoriasis

                      

                    1   1.4%

                     - other

                      

                    1   1.4%

                    Normal reference laboratory values, relative to the limits of the norm of our Institution, are indicated in Table 2 together with the number and percentage of patients with low and high values for each laboratory test, both for the neoplasia and the JIA groups. Furthermore, the comparison of laboratory tests as diagnostic markers of patients in the neoplasia group and in the JIA group, considered as absolute number and percentage of patients with abnormal values, is reported in Table 3. Statistically significant differences in the neoplasia and the JIA groups were found between the following parameters: neutrophils count, haemoglobin (Hb), lactate dehydrogenase (LDH), IgA and C4 subunit of complement (C4) values, antinuclear antibodies (ANA), anti-early antigen (EA) Epstein-Barr virus (EBV) IgG and anti-cytomegalovirus (CMV) IgG titres. No significant differences were found in the other parameters under evaluation and for calcium, phosphorus, anti-muscle antibodies (AMA) and anti-smooth muscle antibodies (ASMA). High LDH value and positivity to anti-CMV IgG were the most predictive factors for neoplasia (sensitivity >70%). High specificity (≥ 80%) for neoplasia was shown by the following factors: abnormal values of neutrophil count, Hb, IgA and C4, and the presence of anti-EA EBV and anti-CMV IgG. High PPVs (≥ 85%) were recorded for abnormal neutrophil count, Hb value and anti-CMV IgG titre. A low NPV (< 50%) was found only for anti-EA EBV and anti-CMV IgG titres. Neutrophils count, Hb, IgA, C4 and anti-CMV IgG titre, shown high LR+ values (>2).
                    Table 2

                    Normal values of diagnostic markers in study

                    Diagnostic markers

                    Normal value (reference value)

                    Neoplasia (N=63)

                    JIA (N=71)

                    Lower values or presence (n/N; %)

                    Normal values (n/N; %)

                    Higher values or positivity (n/N; %)

                    Lower values or present (n/N; %)

                    Normal values (n/N; %)

                    Higher values or positivity (n/N; %)

                    WBC count

                    4-10 × 109/L

                    11/60; 18.3%

                    27/60; 45%

                    22/60; 36.7%

                    3/68; 4.4%

                    35/68; 51.5%

                    30/68; 44.1%

                    Neutrophil count

                    1 × 109/L

                    25/55; 45.5%

                    30/55; 54.5%

                    0/55; 0%

                    2/61; 3.3%

                    59/61; 96.7%

                    0/61; 0%

                    Platelet count

                    150-300 × 109/L

                    34/60; 56.7%

                    13/60; 21.7%

                    13/60; 21.7%

                    2/68; 2.9%

                    17/68; 25%

                    49/68; 72.1%

                    Hemoglobin (Hgb)

                    ≥10 gr/dl

                    34/60; 56.7%

                    26/60; 43.3%

                    NA

                    62/68; 91.2%

                    6/68; 8.8%

                    NA

                    Lactic dehydrogenase (LDH)

                    <500 IU/L

                    NA

                    7/58; 12.1%

                    51/58; 87.9%

                    NA

                    16/49; 32.7%

                    33/49; 67.3%

                    Erythrocyte sedimentation rate (ESR)

                    <20 mm/h

                    NA

                    4/37; 10.8%

                    33/37; 89.2%

                    NA

                    14/68; 20.6%

                    54/68; 79.4%

                    C-reactive protein (CRP)

                    <1 mg/dl

                    NA

                    13/52; 25%

                    39/52; 75%

                    NA

                    14/61; 23%

                    47/61; 77%

                    Antinuclear antibody (ANA)

                    ≥1:80

                    NA

                    16/19; 84.2%

                    3/19; 15.8%

                    NA

                    30/62; 48.4%

                    32/62; 51.6%

                    IgG

                    751–1560 mg/dl

                    9/51; 17.6%

                    35/51; 68.6%

                    7/51; 13.7%

                    2/57; 3.5%

                    35/57; 61.4%

                    20/57; 35.1%

                    IgM

                    46–304 mg/dl

                    4/51; 7.8%

                    47/51; 92.2%

                    0/51; 0%

                    1/57; 1.8%

                    53/57; 93%

                    3/57; 5.3%

                    IgA

                    82–453 mg/dl

                    17/51; 33.3%

                    33/51; 64.7%

                    1/51; 2%

                    6/57; 10.5%

                    49/57; 86%

                    2/57; 3.5%

                    C3

                    79–152 mg/dl

                    1/36; 2.8%

                    14/36; 38.9%

                    21/36; 58.3%

                    3/54; 5.6%

                    29/54; 53.7%

                    22/54; 40.7%

                    C4

                    16–38 mg/dl

                    1/36; 2.8%

                    19/36; 52.8%

                    16/36; 44.4%

                    4/53; 7.5%

                    44/53; 83%

                    5/53; 9.4%

                    Anti-EBV IgM

                    Negative

                    NA

                    37/44; 84.1%

                    7/44; 15.9%

                    NA

                    13/14; 92.9%

                    1/14; 7.1%

                    Anti-EBV IgG

                    Negative

                    NA

                    11/44; 25%

                    33/44; 75%

                    NA

                    7/15; 46.7%

                    8/15; 53.3%

                    Anti-EA EBV IgG

                    Negative

                    NA

                    21/35; 60%

                    14/35; 40%

                    NA

                    10/10; 100%

                    0/10; 0%

                    Anti-CMV IgM

                    Negative

                    NA

                    32/34; 94.1%

                    2/34; 5.9%

                    NA

                    8/10; 80%

                    2/10; 20%

                    Anti-CMV IgG

                    Negative

                    NA

                    9/33; 27.3%

                    24/33; 72.7%

                    NA

                    8/10; 80%

                    2/10; 20%

                    Table 3

                    Comparison of abnormal values of diagnostic markers between neoplasia and JIA patients

                    Diagnostic markers

                    All patients n/N (%)

                    Neoplasia n/N (%)

                    JIA n/N (%)

                    p-value (Neoplasia versus JIA)

                    Sensitivity

                    Specificity

                    PPV

                    NPV

                    LR+

                    LR-

                    WBC count

                    66/128 (51.6)

                    33/60 (55.0)

                    33/68 (48.5)

                    0.484

                          

                    Neutrophil count

                    27/116 (23.3)

                    25/55 (45.5)

                    2/61 (3.3)

                    0.000

                    45.5%

                    96.7%

                    92.5%

                    66.2%

                    13.8

                    0.6

                    Platelet count

                    98/128 (76.6)

                    47/60 (78.3)

                    51/68 (75.0)

                    0.682

                          

                    Hb

                    40/128 (31.3)

                    34/60 (56.7)

                    6/68 (8.8)

                    0.000

                    56.7%

                    91.2%

                    85.0%

                    70.4%

                    6.4

                    0.5

                    LDH

                    84/107 (78.5)

                    51/58 (87.9)

                    33/49 (67.3)

                    0.017

                    87.9%

                    32.7%

                    60.7%

                    69.5%

                    1.3

                    0.4

                    ESR

                    87/105 (82.9)

                    33/37 (89.2)

                    54/68 (79.4)

                    0.281

                          

                    CRP

                    86/113 (76.1)

                    39/52 (75.0)

                    47/61 (77.0)

                    0.828

                          

                    ANA

                    35/81 (43.2)

                    3/19 (15.8)

                    32/62 (51.6)

                    0.008

                    15.8%

                    48.4%

                    8.5%

                    65.2%

                    0.3

                    1.7

                    IgG

                    38/108 (35.2)

                    16/51 (31.4)

                    22/57 (38.6)

                    0.545

                          

                    IgM

                    8/108 (7.4)

                    4/51 (7.8)

                    4/57 (7.0)

                    1.000

                          

                    IgA

                    26/108 (24.1)

                    18/51 (35.3)

                    8/57 (14.0)

                    0.013

                    35.3%

                    86.0%

                    69.2%

                    59.7%

                    2.5

                    0.8

                    C3

                    47/90 (52.2)

                    22/36 (61.1)

                    25/54 (46.3)

                    0.200

                          

                    C4

                    26/89 (29.2)

                    17/36 (47.2)

                    9/53 (17.0)

                    0.004

                    47.2%

                    83.0%

                    65.3%

                    69.8%

                    2.8

                    0.6

                    Anti-EBV IgM

                    8/58 (13.8)

                    7/44 (15.9)

                    1/14 (7.1)

                    0.665

                          

                    Anti-EBV IgG

                    41/59 (69.5)

                    33/44 (75.0)

                    8/15 (53.3)

                    0.192

                          

                    Anti-EA EBV IgG

                    14/45 (31.1)

                    14/35 (40.0)

                    0/10 (0)

                    0.019

                    40.0%

                    100%

                    1.0%

                    32.2%

                    -

                    0.6

                    Anti-CMV IgM

                    4/44 (9.1)

                    2/34 (5.9)

                    2/10 (20.0)

                    0.218

                          

                    Anti-CMV IgG

                    26.43 (60.5)

                    24/33 (72.7)

                    2/10 (20.0)

                    0.007

                    72.7%

                    80.0%

                    92.3%

                    47.0%

                    3.6

                    0.3

                    The combination of all three abnormal values in neutrophil count, Hb and LDH provide an increase in sensitivity (93.3%) and in specificity (100%).

                    Table 4 reports the results of diagnostic markers, considered as number and percentage of patients with abnormal values, among patients with ALL compared with those of patients with JIA. Statistically significant differences were found between the two groups with regard to neutrophil count, Hb, IgA and C4 values, ANA, anti-EA EBV and anti-CMV IgG titres. No significant differences were found in the abnormal values of the other parameters under evaluation and for calcium, phosphorus, AMA and ASMA. The most predictive factors for ALL were as follows: with high sensitivity (>70%) positivity to anti-CMV IgG only; with high specificity (≥80%), neutrophil count, Hb value, IgA, C4, anti-EA IgG and anti-CMV IgG titres. High PPVs (>80%) were recorded for neutrophil count, Hb value and anti-CMV IgG titre. NPVs were low (<50%) for anti-EA IgG titre. Neutrophils count, Hb, IgA, C4 and anti-CMV IgG titre, shown high LR+ values (>2).
                    Table 4

                    Comparison of abnormal values of diagnostic markers between ALL and JIA patients

                    Diagnostic markers

                    All patients n/N (%)

                    ALL n/N (%)

                    JIA n/N (%)

                    p-value (ALL versus JIA)

                    Sensitivity

                    Specificity

                    PPV

                    NPV

                    LR+

                    LR-

                    WBC count

                    59/113 (52.2)

                    26/45 (57.8)

                    33/68 (48.5)

                    0.345

                          

                    Neutrophil count

                    23/101 (22.8)

                    21/40 (52.5)

                    2/61 (3.3)

                    0.000

                    52.5%

                    96.7%

                    91.3%

                    75.6%

                    15.9

                    0.5

                    Platelet count

                    87/113 (77.0)

                    36/45 (80.0)

                    51/68 (75)

                    0.650

                          

                    Hb

                    32/113 (28.3)

                    26/45 (57.8)

                    6/68 (8.8)

                    0.000

                    57.8%

                    91.2%

                    81.2%

                    76.5%

                    6.6

                    0.5

                    LDH

                    70/92 (76.1)

                    37/43 (86.0)

                    33/49 (67.3)

                    0.050

                          

                    ESR

                    78/95 (82.1)

                    24/27 (88.9)

                    54/68 (79.4)

                    0.379

                          

                    CRP

                    73/99 (73.7)

                    26/38 (68.4)

                    47/61 (77.0)

                    0.358

                          

                    ANA

                    34/76 (44.7)

                    2/14 (14.3)

                    32/62 (51.6)

                    0.016

                    14.3%

                    48.4%

                    5.8%

                    71.4%

                    0.3

                    1.8

                    IgG

                    34/96 (35.4)

                    12/39 (30.8)

                    22/57 (38.6)

                    0.517

                          

                    IgM

                    6/96 (6.3)

                    2/39 (5.1)

                    4/5 (7.0)

                    1.000

                          

                    IgA

                    23/96 (24.0)

                    15/39 (38.5)

                    8/57 (14.0)

                    0.008

                    38.5%

                    86%

                    65.2%

                    67.1%

                    2.8

                    0.7

                    C3

                    42/82 (51.2)

                    17/28 (60.7)

                    25/54 (46.3)

                    0.250

                          

                    C4

                    23/81 (18.4)

                    14/28 (50.0)

                    9/53 (17.0)

                    0.004

                    50%

                    83%

                    60.8%

                    75.8%

                    2.9

                    0.6

                    Anti-EBV IgM

                    8/50 (16.0)

                    7/36 (19.4)

                    1/14 (7.1)

                    0.414

                          

                    Anti-EBV IgG

                    35/51 (68.6)

                    27/36 (75.0)

                    8/15 (53.3)

                    0.187

                          

                    Anti-EA EBV IgG

                    12/40 (30.0)

                    12/30 (40.0)

                    0/10 (0)

                    0.019

                    40.0%

                    100%

                    1.0%

                    35.7%

                    -

                    0.6

                    Anti-CMV IgM

                    4/40 (10.0)

                    2/30 (6.7)

                    2/10 (20.0)

                    0.256

                          

                    Anti-CMV IgG

                    24/39 (61.5)

                    22/29 (75.9)

                    2/10 (20.0)

                    0.003

                    75.9%

                    80.0%

                    91.6%

                    53.3%

                    3.8

                    0.3

                    Comparing patients with ALL to those with JIA, the combination of both abnormal values of neutrophil count and Hb did not show any increase in sensitivity (46.8%), whereas an increase in specificity was observed (98.5%).

                    As far as clinical data are concerned, monolateral and bilateral musculoskeletal pain were observed with similar frequency in children with JIA (32.4% and 38.0% respectively) and in children with neoplasia (31.7% and 38.1% respectively). Furthermore, fever was significantly more recurrent in children with neoplasia (71.4%) as compared to children with JIA (33.8%) (p = 0.000). Finally, lymphadenopathy was significantly more frequent in children with neoplasia (23.8%) than in children with JIA (7.0%) (p = 0.007).

                    Discussion

                    Musculoskeletal pain is a frequent complaint among children but only in few cases it implies severe diseases such as malignancies or chronic inflammatory diseases. Only in very few cases musculoskeletal pain is an isolated sign hindering the formulation of the diagnosis. In some of those cases general practitioners or paediatricians address the patient to the rheumatologist or the orthopaedist who tend to consider musculoskeletal symptoms as a sign of a chronic inflammatory disease. Therefore they prescribe analyses in order to validate their clinical hypothesis or start treatment without a clear diagnosis. In such a case, treatment with corticosteroids relieves symptoms thus causing a further delay in the diagnosis. Even when both diagnostic hypotheses are included, it can be hard to distinguish the clinical signs of JIA from malignancies because symptoms at the onset may be the same [3, 9]. Moreover, in the absence of pathognomonic test the diagnosis of JIA requires the exclusion of all the other causes of musculoskeletal pain. Furthermore, when no haematological signs are present, even leukaemia or a tumour could be difficult to detect. This clinical overlapping explains the need to always exclude a malignancy in children with musculoskeletal symptoms, especially when the clinical pattern is not characteristic of a specific rheumatic disease and/or in the presence of organomegaly or abnormal laboratory or imaging data.

                    A limited number of studies have been conducted in order to examine the value of diagnostic markers in the differential diagnosis between JIA and malignancies in children [79] and results are often inconsistent. In order to identify early parameters useful for a differential diagnosis, clearly defining the role of laboratory tests in terms of usage within the clinical diagnostic algorithms and the patient population for whom they are intended, in the present study we retrospectively evaluated ten-years data of two different groups of children with musculoskeletal pain, one affected by tumour and the other by JIA. No significant difference was found between the two groups for sex and age at the time of the diagnosis. High C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were not relevant parameters, being CRP slightly higher among the JIA group, but with no statistically significant difference. Some authors suggest taking the neutrophil count carefully into consideration in a child complaining musculoskeletal pain [2, 9]. Our results confirm a statistically significant difference in the neutrophil count between the two groups, being lower values significantly most frequent among patients with tumour (45.5% vs 3.3%) or leukaemia (52.5%), with high specificity, PPV and LR+, but low sensitivity. This means that a normal result of this test is very frequent among “non tumour” patients even though an altered result is not a clear sign of a “tumour/leukaemia” patient.

                    The same results were obtained for the haemoglobin levels: anaemia (i.e. Hb <10 g/dl) was more frequently found in the tumour group (56.7% vs 8.8%) or in the leukaemia group (57.8%) with a statistically significant difference. However, it has been reported that anaemia from chronic illness does occur in children with JIA and, for this parameter, we found low sensitivity (56.7%) for tumours. An abnormal platelet count was observed in both groups of patients, with lower values among the tumour group and higher values among the JIA group (p <0.05).

                    According to literature, high LDH level proved a useful predictive factor for tumours: abnormal values were more prevalent among the tumour group (87.9% vs 67.3%; sensitivity 88.0%). In fact, as previously reported in ALL patients [9], a twofold or even higher increase was found exclusively among children with malignancies. Consequently, if a child complains musculoskeletal pain, high LDH level should be considered suspicious and it requires further analyses to exclude a malignancy.

                    Moreover, in the comparison between the patients with tumour and those with JIA, the combination of all three abnormal values in neutrophil count, Hb and LDH increased sensitivity and specificity.

                    We also investigated clinical parameters like fever and lymphadenopathy which resulted significantly more frequent in patients with tumour despite a high number of missing data. However, previous papers have already reported the limited value of these clinical parameters for the comparison of ALL and JIA [911].

                    Some diagnostic tests such as ANA and complement have been reported as not meaningful to differentiate tumours and JIA [9]. In our study the frequency of positive ANA patients was higher among the JIA group and the difference was statistically significant, but this test was characterized by low sensitivity and low specificity. No significant difference in the other screened auto-antibodies appeared between the two groups. Furthermore, no significant difference was detected in the immunoglobulin profile even though we found abnormal IgA values more frequently among the tumour group and this result was statistically significant with high specificity.

                    An odd result, seemingly difficult to comment, concerns a positive anti-CMV IgG titre found more frequently among patients with tumours than among JIA patients, with a statistically significant difference and with high specificity and high sensitivity, high PPV and low NPV. Our data showed that the presence of these antibodies is the most valid feature in patients with tumour or leukaemia versus patients with JIA, although the low number of tests taken in JIA patients makes the numbers less reliable. Indeed, it has been reported that leukemic patients have a higher titre of antibodies against many herpes viruses than the healthy population [12, 13].

                    Conclusions

                    In conclusion, our results suggest that even small changes in the neutrophil count are of critical diagnostic value. In cases where such alterations are associated with low Hb levels and high LDH, the probability of a diagnosis of neoplasia is very elevated. Our study highlights the importance of accurate diagnosis for the appropriate and effective management to improve patient outcomes. Further prospective studies considering a more numerous sample would better evaluate the clinical utility of laboratory tests for the early differential diagnosis of leukaemia/tumour or JIA.

                    Abbreviations

                    JIA: 

                    Juvenile idiopathic arthritis

                    ALL: 

                    Acute lymphoblastic leukaemia

                    RF: 

                    Rheumatoid factor

                    WBC: 

                    White blood cells

                    Hb: 

                    Haemoglobin

                    LDH: 

                    Lactate dehydrogenase

                    ESR: 

                    Erythrocyte sedimentation rate

                    CRP: 

                    C-reactive protein

                    ANA: 

                    Antinuclear antibodies

                    AMA: 

                    Antimuscle antibodies

                    ASMA: 

                    Anti smooth muscle antibodies

                    EBV: 

                    Epstein-barr virus

                    EA: 

                    Early antigen

                    CMV: 

                    Cytomegalovirus

                    PPV: 

                    Positive predictive value

                    NPV: 

                    Negative predictive value

                    NA: 

                    Not applicable

                    LR+: 

                    Positive likelihood ratio

                    LR-: 

                    Negative likelihood ratio.

                    Declarations

                    Acknowledgements

                    We wish to thank Dr Daniela Bonfiglio for her precious assistance in English language, Mr Giuseppe Auteri for secretarial work.

                    Authors’ Affiliations

                    (1)
                    Department “GF Ingrassia”, University of Catania
                    (2)
                    Unit of Paediatric Haematology and Oncology, Department of Paediatrics, University of Catania
                    (3)
                    Unit of Paediatric Day Hospital, Department of Paediatrics, University of Catania

                    References

                    1. Abu-Arafeh I, Russell G: Recurrent limb pain in schoolchildren. Arch Dis Child 1996, 74:336–339.PubMedView Article
                    2. Jonsson OG, Sartain P, Ducore JM, Buchanan GR: Bone pain as an initial symptom of childhood acute lymphoblastic leukemia: association with nearly normal hematologic indexes. J Pediatr 1990, 117:233–237.PubMedView Article
                    3. Trapani S, Grisolia F, Simonini G, Calabri GB, Falcini F: Incidence of occult cancer in children presenting with musculoskeletal symptoms: a 10-year survey in a pediatric rheumatology unit. Semin Arthritis Rheum 2000, 29:348–359.PubMedView Article
                    4. Cabral DA, Tucker LB: Malignancies in children who initially present with rheumatic complaints. J Pediatr 1999, 134:53–57.PubMedView Article
                    5. Ravelli A, Martini A: Juvenile idiopathic arthritis. Lancet 2007, 369:767–778.PubMedView Article
                    6. Bradlow A, Barton C: Arthritic presentation of childhood leukaemia. Postgrad Med J 1991, 67:562–564.PubMedView Article
                    7. Gupta D, Singh S, Suri D, Ahluwalia J, Das R, Varma N: Arthritic presentation of acute leukemia in children: experience from a tertiary care centre in North India. Rheumatol Int 2010, 30:767–770.PubMedView Article
                    8. Marwaha RK, Kulkarni KP, Bansal D, Trehan A: Acute lymphoblastic leukemia masquerading as juvenile rheumatoid arthritis: diagnostic pitfall and association with survival. Ann Hematol 2010, 89:249–254.PubMedView Article
                    9. Jones OY, Spencer CH, Bowyer SL, Dent PB, Gottlieb BS, Rabinovich CE: A multicenter case–control study on predictive factors distinguishing childhood leukemia from juvenile rheumatoid arthritis. Pediatrics 2006, 117:840–844.View Article
                    10. Kobayashi D, Satsuma S, Kamegaya M, et al.: Musculoskeletal conditions of acute leukemia and malignant lymphoma in children. J Pediatr Orthop B 2005, 14:156–161.PubMedView Article
                    11. Sinigaglia R, Gigante C, Bisinella G, Varotto S, Zanesco L, Turra S: Musculoskeletal manifestations in pediatric acute leukemia. J Pediatr Orthop 2008, 28:20–28.PubMedView Article
                    12. Tesse R, Santoro N, Giordano P, Cardinale F, De Mattia D, Armenio L: Association between DEFB1 gene haplotype and herpes viruses seroprevalence in children with acute lymphoblastic leukemia. Pediatr Hematol Oncol 2009, 26:573–582.PubMedView Article
                    13. Loutfy SA, Alam El-Din HM, Ibrahim MF, Hafez MM: Seroprevalence of herpes simplex virus types 1 and 2, Epstein-Barr virus, and cytomegalovirus in children with acute lymphoblastic leukemia in Egypt. Saudi Med J 2006, 27:1139–1145.PubMed
                    14. Pre-publication history

                      1. The pre-publication history for this paper can be accessed here:http://​www.​biomedcentral.​com/​1471-2431/​13/​15/​prepub

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                    © Agodi et al.; licensee BioMed Central Ltd. 2013

                    This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.