Isolated thrombocytopenia in childhood: what if it is not immune thrombocytopenia?

Immune or inherited thrombocytopenia? A population-based cohort study on children and adolescents presenting with a low platelet count

BACKGROUND

Thrombocytopenia is a common hematologic finding in children and adolescents. Immune thrombocytopenia (ITP) is the most common cause of this finding, but the differential diagnosis includes a growing list of genetic disorders. We aimed to report differences in phenotypes of patients with ITP, inherited platelet disorder (IPD)/primary immunodeficiency disorder (PID), and other causes, with a focus on differentiating ITP from inherited thrombocytopenia.

PROCEDURE

This retrospective, population-based observational cohort from 2006 to 2020 involved 506 Finnish children under 16 years of age presenting with isolated thrombocytopenia.

RESULTS

Of the 506 participants, 79.7% had ITP, 6.7% had IPD/PID, and 13.6% had other causes of thrombocytopenia. A platelet count of ≤12 × 109/L best distinguished between ITP and other reasons with a sensitivity of 60% and a specificity of 80%. Among patients with the lowest platelet count of less than 10 × 109/L, 95.9% had ITP, 3.3% had IPD/PID, and 0.8% had other causes. Severe bleeding events were reported in 20 patients (4.0%), but there were no cases of intracranial or fatal bleeding due to thrombocytopenia. Up to 50% of patients with a high suspicion of inherited thrombocytopenia remained without a specific diagnosis despite genetic testing.

CONCLUSIONS

ITP remains the most common cause of thrombocytopenia. A platelet count of ≤12 × 109/L often leads to an ITP diagnosis. Genetic disorders are rare but should be suspected in patients with persisting thrombocytopenia, especially with platelet counts constantly above 12 × 109/L, a positive family history, or atypical clinical features.

Recommendations for the management of acute immune thrombocytopenia in children. A Consensus Conference from the Italian Association of Pediatric Hematology and Oncology

BACKGROUND

Immune thrombocytopenia (ITP) is an acquired immune-mediated bleeding disorder characterized by isolated thrombocytopenia. Its estimated yearly incidence in the pediatric population is 1.9-6.4/100,000. ITP in children is usually a self-limiting and benign disorder. The clinical management of children with ITP often remains controversial, as robust randomized trials on the management of this disorder are lacking. Treatments vary widely in clinical practice and existing guidelines from hematology societies on clinical management offer indications based largely on expert opinion rather than strong evidence.

MATERIALS AND METHODS

The Coagulative Disorder Working Group of the Italian Association of Pediatric Hematology and Oncology (AIEOP) developed this document to collect shared expert opinions on the management of newly diagnosed ITP, updating previous guidelines and providing recommendations to pediatricians. Each statement has been given a score expressing the strength of evidence, appropriateness and agreement among participants.

RESULTS

Clear-cut definitions of the clinical phases of the disease and clinical response are stated. Recommendations are given regarding the classification of bleeding symptoms, evaluation of bleeding risk, diagnosis, and prognostic factors. Specific recommendations for treatment include indications for first-line (intravenous immunoglobulins, steroids) and second-line (combined therapy, thrombopoietin receptor agonists, immunosuppressive drugs, rituximab) therapeutic agents, as well as hemorrhagic emergency and supportive treatment, including emergency splenectomy. The optimal follow-up schedule, the relation between ITP and vaccines and health-related quality-of-life issues are also discussed.

DISCUSSION

The panel achieved broad consensus on issues related to how to treat children with newly diagnosed ITP, providing a comprehensive review of all relevant clinical aspects.

MYH9-Related Disorder (MYH9-RD): An Under-Recognized Family of Giants Among the Inherited Thrombocytopenias

Inherited thrombocytopenia is a rare phenomenon. MYH9-related disorder (MYH9-RD) is one such pathology characterized by thrombocytopenia and giant platelets with the presence of cytoplasmic inclusion bodies in the granulocytes. The condition is often misdiagnosed as immune thrombocytopenia (ITP) due to its similarities in clinical phenotype and often no associated secondary causes. Ensuing treatments, frequently unnecessary, may predispose to adverse outcomes or perceived a lack of improvement. We report a young lady in her 20s who was eventually found to have MYH9-RD after her second pregnancy. A strong family history of thrombocytopenia, revision of her blood film (presence of giant platelets with no obvious platelet clumping, and the presence of Dohle body-like inclusions in the neutrophils), a lack of response to corticosteroids (treatment for ITP) eventually pointed us to this diagnosis. This case report aims to educate physicians regarding MYH9-RD as a rare but important entity when approaching chronic thrombocytopenia.

The association between platelet glycoprotein-specific antibodies and response to short-term high-dose dexamethasone with prednisone maintenance treatment in adult patients with primary immune thrombocytopenia

OBJECTIVE

The aim of the present study was to detect the association between platelet glycoprotein-specific autoantibodies and the patient response to short-term high-dose dexamethasone (HD-DXM) + prednisone maintenance treatment.

METHODS

The data from 112 adult patients newly diagnosed with ITP who were administered first-line HD-DXM + prednisone maintenance therapy between January 2016 and January 2021 were retrospectively analyzed.

RESULTS

A total of 72 patients positive for platelet glycoprotein-specific antibodies were enrolled in the antibody-positive group, and 40 patients not positive for platelet glycoprotein-specific antibodies were enrolled in the antibody-negative group. In the antibody-positive group, six platelet glycoprotein-specific antibody types were found: 41.67% of the patients were anti-GP IIb/IIIa-positive only, 5.56% were anti-GP Ib/IX-positive only, 5.56% were anti-P-selectin-positive only, 19.44% were anti-GP IIb/IIIa- and anti-GP Ib/IX-positive, 16.67% were anti-GP Ib/IX- and P-selectin-positive and 11.11% were positive for all three antibodies. There was no significant difference in the overall response rate between the antibody-positive group and the antibody-negative group (94.44 versus 80.00%, p = .221). However, the CR rate was significantly higher in the antibody-positive group than in the antibody-negative group (69.44% versus 40.00%, p = .032). The logistic regression analysis revealed that platelet glycoprotein-specific antibody positivity and age were two factors that could affect patient response.

CONCLUSIONS

The present study discovered that adult patients newly diagnosed with ITP who had positive platelet glycoprotein-specific antibody test results were likely to achieve a better response after treatment with HD-DXM + prednisone maintenance.

Association between P-Selectin Autoantibody Positive and Response to Steroid Treatment in Newly Diagnosed Immune Thrombocytopenia Patients

OBJECTIVE

This study aimed to detect the association between P-selectin autoantibody positive and response to steroid treatment in newly diagnosed immune thrombocytopenia (ITP) patients.

METHODS

The data from 105 newly diagnosed adult ITP patients administered with first-line of steroid treatment from October 2016 to May 2021 were retrospectively analyzed. Treatment responses were evaluated within 3 months after the onset of treatment.

RESULTS

Among the 105 patients, 80.00% (84/105) of patients presented with platelet glycoprotein-specific antibody positive; 44.76% (47/105) patients were anti-P-selectin positive, while 35.24% (37/105) were anti-P-selectin negative. No significant difference in overall response was observed between patients who were anti-P-selectin positive and those who were anti-P-selectin negative (74.47% vs. 89.19, χ2 = 2.910, p = 0.088). But patients who were anti-P-selectin negative had significantly higher complete response rate, compared to those who were anti-P-selectin positive (72.97% vs. 48.94%, χ2 = 4,965, p = 0.026). Logistic regression analysis revealed that anti-GP IIb/IIIa positive (OR = 3.114, p = 0.010, 95% CI: 1.313-7.388) and anti-P-selectin positive (OR = 0.309, p = 0.036, 95% CI: 0.127-0.753) were two factors that could affect patients' response.

CONCLUSIONS

Our study found that ITP patients with anti-GP IIb/IIIa may have a higher response to steroid treatment, but anti-P-selectin-mediated-ITP might be less responsive to steroid treatment. In adults with ITP, the presence of anti-P-selectin autoantibodies is a predictive factor for poor response to steroid treatment.

Misdiagnosed thrombocytopenia in children and adolescents: analysis of the Pediatric and Adult Registry on Chronic ITP

Primary immune thrombocytopenia (ITP) in children is a diagnosis of exclusion, but cases of secondary ITP and nonimmune thrombocytopenia (non-IT) are generally difficult to recognize in a timely fashion. We describe a pediatric population with a revised diagnosis of secondary ITP or non-IT within 24 months of follow-up. Data were extracted from the Pediatric and Adult Registry on Chronic ITP, an international multicenter registry collecting data prospectively in patients with newly diagnosed primary ITP. Between 2004 and 2019, a total of 3974 children aged 3 months to 16 years were included. Secondary ITP and non-IT were reported in 113 patients (63 female subjects). Infectious (n = 53) and autoimmune (n = 42) diseases were identified as the main causes, with median ages at diagnosis of 3.2 years (interquartile range: 1.2; 6.7 years) and 12.4 years (interquartile range: 7.6; 13.7 years), respectively. Other causes included malignancies, aplastic anemia, immunodeficiency, and drug use. Patients with malignancy and aplastic anemia had significantly higher initial platelet counts (37 and 52 × 109/L) than did those with infection or autoimmune diseases (12 and 13 × 109/L). Characteristics of patients with secondary ITP due to infection were similar to those of children with primary ITP at first presentation, indicating similar mechanisms. Significant differences were found for age, sex, comorbidities, initial bleeding, sustained need for treatment, and disease persistence for the remaining noninfectious group compared with primary ITP. Based on our findings, we propose a diagnostic algorithm that may serve as a basis for further discussion and prospective trials.

Renal Biopsy-induced Hematoma and Infection in a Patient with Asymptomatic May-Hegglin Anomaly

The May-Hegglin anomaly is characterized by inherited thrombocytopenia, giant platelets, and leukocyte cytoplasmic inclusion bodies. The Fechtner, Sebastian, and Epstein syndromes are associated with mutations of the MYH9-coding nonmuscle myosin heavy chain ⅡA, similar to the May-Hegglin anomaly, and are together classified as MYH9 disorders. MYH9 disorders may include symptoms of Alport syndrome, including nephritis and auditory and ocular disorders. A 6-year-old boy was diagnosed with an MYH9 disorder after incidental discovery of hematuria and proteinuria. Focal segmental glomerulosclerosis was detected on renal biopsy. However, despite no prior bleeding diatheses, he developed a large post-biopsy hematoma despite a preprocedural platelet transfusion calculated to increase the platelet count from 54,000/μL to >150,000/μL. Idiopathic thrombocytopenic purpura is a major cause of pediatric thrombocytopenia following acute infection or vaccination, and patients with MYH9 disorders may be misdiagnosed with idiopathic thrombocytopenic purpura and inappropriately treated with corticosteroids. Careful differential diagnosis is important in thrombocytopenic patients with hematuria and proteinuria for the early detection of thrombocytopenia. Patients with MYH9 disorders require close follow-up and treatment with angiotensin Ⅱ receptor blockers to prevent the onset of progressive nephritis, which may necessitate hemodialysis or renal transplantation. The need for renal biopsy in patients with MYH9 disorders should be carefully considered because there could be adverse outcomes even after platelet transfusion.

Haematologist-reviewed peripheral blood smear in paediatric practice

Manual examination of the peripheral blood smear (PBS) is currently performed on a fraction of samples sent for automated complete cell count. 39 children (age range 0-16.2 years) referred to a private paediatric practice during a 16-month period were retrospectively reviewed. Clinical scenarios, haematological features, laboratory-initiated PBS review, haematologist's PBS review and final diagnosis were described. Clinical indications included isolated thrombocytopenia (n = 10), unexplained bruises (n = 5), acute febrile illnesses (n = 11), anaemia (n = 8) and others (n = 5). The laboratory reviewed the PBS in 30 cases according to preset criteria and made no conclusive remarks. All slides were reviewed by a haematologist and a diagnosis was made in 27 (69%) cases, including 7 (78%) of the nine slides the laboratory did not review. The practice of laboratory-initiated PBS review requires re-evaluation. Haematologist-reviewed PBS is an important diagnostic tool for children with anaemia, bleeding disorders and acute febrile illnesses.