Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia presenting in an infant with a subdural hematoma

BACKGROUND

Juvenile myelomonocytic leukemia (JMML) is a rare childhood hematopoietic disorder typically presenting with hepatosplenomegaly, lymphadenopathy, pallor, fever, and cutaneous findings. The authors report the first case, to our knowledge, of JMML presenting in a pediatric patient with a subdural hematoma.

CASE DESCRIPTION

A 7-month old male with recurrent respiratory infections and a low-grade fever presented with a full fontanelle and an increasing head circumference and was found to have chronic bilateral subdural collections. Abusive head trauma, infectious, and coagulopathy workups were unremarkable, and the patient underwent bilateral burr holes for evacuation of the subdural collections. The postoperative course was complicated by the development of thrombocytopenia, anemia, and an acute subdural hemorrhage which required evacuation. Cytologic analysis of the subdural fluid demonstrated atypical cells, which prompted flow cytometric analysis, a bone marrow biopsy, and ultimately a diagnosis of JMML. Following chemotherapy, the patient's counts improved, and he subsequently underwent a hematopoietic stem cell transplant.

CONCLUSION

Subdural collections may rarely represent the first presenting sign of hematologic malignancies. In patients with a history of recurrent infections and a negative workup for abusive head trauma, clinicians should include neoplastic etiologies in the differential for chronic subdural collections and have a low threshold for fluid analysis.

Pediatric Neoplasms Presenting with Monocytosis

PURPOSE OF REVIEW

Juvenile myelomonocytic leukemia (JMML) is a rare but severe pediatric neoplasm with hematopoietic stem cell transplant as its only established curative option. The development of targeted therapeutics for JMML is being guided by an understanding of the pathobiology of this condition. Here, we review JMML with an emphasis on genetics in order to (i) demonstrate the relationship between JMML genotype and clinical phenotype and (ii) explore potential genetic targets of novel JMML therapies.

RECENT FINDINGS

DNA hypermethylation studies have demonstrated consistently that methylation is related to disease severity. Increasing understanding of methylation in JMML may open the door to novel therapies, such as DNA methyltransferase inhibitors. The PI3K/AKT/MTOR, JAK/STAT, and RAF/MEK/ERK pathways are being investigated as therapeutic targets for JMML. Future therapy for JMML will be driven by an increased understanding of pathobiology. Targeted therapeutic approaches hold potential for improving outcomes in patients with JMML.

A 27-Year-Old Patient Fulfilling the Diagnostic Criteria of Both CMML and JMML

Chronic myelomonocytic leukaemia (CMML) and juvenile myelomonocytic leukaemia (JMML) are two disease entities that come under the myelodysplastic/myeloproliferative neoplasms category. Each of the two conditions has its own diagnostic criteria. In addition, they have different ages of presentation; while CMML is typically a disease of the elderly, JMML is a disease of young children. Here we are presenting the case of a 27-year-old male patient who, at the time of diagnosis, fulfilled the diagnostic criteria of both diseases. In addition he had radiological changes of type 1 neurofibromatosis. Possible explanations of the patient case have been discussed.

How I treat juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a unique, aggressive hematopoietic disorder of infancy/early childhood caused by excessive proliferation of cells of monocytic and granulocytic lineages. Approximately 90% of patients carry either somatic or germline mutations of PTPN-11, K-RAS, N-RAS, CBL, or NF1 in their leukemic cells. These genetic aberrations are largely mutually exclusive and activate the Ras/mitogen-activated protein kinase pathway. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the therapy of choice for most patients with JMML, curing more than 50% of affected children. We recommend that this option be promptly offered to any child with PTPN-11-, K-RAS-, or NF1-mutated JMML and to the majority of those with N-RAS mutations. Because children with CBL mutations and few of those with N-RAS mutations may have spontaneous resolution of hematologic abnormalities, the decision to proceed to transplantation in these patients must be weighed carefully. Disease recurrence remains the main cause of treatment failure after HSCT. A second allograft is recommended if overt JMML relapse occurs after transplantation. Recently, azacytidine, a hypomethylating agent, was reported to induce hematologic/molecular remissions in some children with JMML, and its role in both reducing leukemia burden before HSCT and in nontransplant settings requires further studies.

Juvenile myelomonocytic leukemia: report of seven cases and review of literature

Juvenile myelomonocytic leukemia (JMML) is a rare, aggressive, clonal hematopoietic disorder of childhood with features of both myelodysplasia (thrombocytopenia, anemia) and myeloproliferation (leukocytosis, monocytosis). In most cases there is marrow hypercellularity, splenomegaly, and extramedullary involvement. In 1997 an international consensus on terminology was reached and guidelines/criteria for diagnosis were proposed. A recent World Health Organization classification described the current diagnostic criteria of JMML. Although the diagnosis of JMML has been facilitated, it can be challenging, especially in the early stages or when it 1st presents as an extramedullary tumor. We report a series of 7 cases diagnosed over a period of 10 years (from January 1, 1996, to December 31, 2005). Two cases had interesting associated findings that would potentially lead to delay in diagnosis or misdiagnosis. Two other cases had extramedullary involvement with symptoms referable to the organs of involvement at presentation. Clinical and pathologic findings are summarized with a review of relevant literature.