Hypereosinophilic syndrome preceding a diagnosis of B-cell lymphoma

Hypereosinophilic syndrome (HES) is a rare condition characterized by eosinophilia and organ destruction secondary to eosinophilic infiltration. The coexistence of primary B-cell lymphoma and hypereosinophilic syndrome is extremely rare. We present a case of HES that preceded the diagnosis of diffuse large B-cell lymphoma.A 70-year-old man presented with a 3-month history of diarrhea and 30-pound weight loss. Complete blood count showed a white blood cell count of 7452/µL with eosinophils of 42% (absolute eosinophil count 3130). Colonoscopy showed eosinophilic infiltrate in the lamina propria and muscularis mucosa. Bone marrow biopsy showed elevated myeloid: erythroid ratio (6:1), increased mature and immature eosinophilic infiltration (10% of nucleated cells). Molecular studies were negative for Fip1-like1-platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) translocation and PDGFRB and FGFR mutations, indicating nonclonal eosinophilia. Treatment was initiated with prednisone (1 mg/kg) and hydroxyurea 500 mg twice daily. He responded with complete resolution of symptoms. Five months later, the patient presented with right lower quadrant pain. Abdominal/pelvis computed tomography (CT) showed bulky right inguinal lymphadenopathy and biopsy revealed CD10+ diffuse large B-cell lymphoma (DLBCL). Further staging workup showed the stage to be IIB. He received 6 cycles of chemotherapy and involved field radiation therapy. He achieved complete remission.Reviewing the literature indicates only one case of similar presentation with concomitant HES and DLBCL. Eosinophilia is routinely encountered in clinical practice and as such physicians must be aware of the rarer, more malevolent underlying associations of this condition so as to aid early diagnosis and prompt treatment.