A Rare Case of Hypereosinophilia: 8p11 Myeloproliferative Syndrome (EMS) in a 7 Month Old

Rationale: EMS is an aggressive neoplasm due to chromosomal translocations involving the fibroblast growth factor receptor 1 (FGFR1) gene. It is associated with eosinophilia and lymphadenopathy. Unlike other causes of hypereosinophilic syndrome (HES), EMS does not respond to therapy with tyrosine kinase inhibitors. Although it can present at any age, it has not been reported in infancy. 

Methods: FISH evaluation of bone marrow was performed by Washington University Department of Cytogenomics. 

Results: Patient was initially admitted at 7 months old for rash, failure to thrive and lymphadenopathy with incomplete immunizations. WBC count 32 thousand/mm3 with absolute eosinophils 10,880/mm3, monocytes 4,160/mm3, IgG 1,318 mg/dl, IgE 19.2 mg/dl. Infectious and immunological work up was normal including Hyper-IgE panel, DHR, ALPS panel and PDGFRA gene sequencing for HES. Rash biopsy showed lichenoid infiltrates representing nonspecific lymphocytic inflammation. Bone marrow biopsy showed increased but mature eosinophils without evidence of dysplasia or increased blasts. Subsequent FISH analysis showed FGFR1 rearrangement in 74% of cells [46,XY,t(8;9)(p11.2;q34)] consistent with EMS. He developed significant worsening of the rash with erosions, bullae and mucositis and was found to have HHV-6 that mildly responded to foscarnet. He was started on chemotherapy until receiving allogeneic stem cell transplant at age 1.  

Conclusions: We believe this is the youngest reported case of EMS, with only 14 other cases with this translocation in the literature. It was diagnosed and treated prior to transformation to acute myeloid leukemia. Although the majority of EMS cases have an unfavorable prognosis, early recognition and transplantation could increase overall survival rate.