Hypereosinophilia in a patient with refractory eczema and ALK-negative anaplastic large cell lymphoma

Abstract

A 41-year-old man with refractory eczema on immunosuppressants developed swinging fever and dyspnoea, with left pleural effusion and left axillary and groin lymphadenopathy (2–3 cm) found in physical examination. Clinically there was no eczema flare-up. Laboratory tests showed hypereosinophilia (79.1×109/L) and elevated LDH (520 U/L) and ALP (187 U/L). Some dysplastic eosinophils showing hyposegmented nuclei and hypogranular cytoplasm were noted on blood smears. Workup for parasites, allergy and autoimmune markers was unremarkable. Thoracentesis yielded exudative effusate with numerous lymphocytes (WBC >1000/mm3) but no malignant cell was evident. FNAC of lymph nodes found eosinophilic infiltrate only. Bone marrow examination revealed marked eosinophilia with similar dysplastic features and megakaryocytic hyperplasia, raising suspicion of myeloproliferative neoplasms. Karyotyping, molecular tests for JAK2 mutation and BCR-ABL1 fusion, and FISH for FIP1L1-PDGFRA, PDGRFB and FGFR1 rearrangements were unremarkable. Excisional biopsy of left groin lymph node was then pursued and demonstrated sheets of pleomorphic neoplastic cells with focal ‘hallmark cells’. Anaplastic large cell lymphoma (ALK–CD30+CD3+CD8+) was diagnosed. PET/CT scan revealed a stage-IV disease with extensive supra- and infra-diaphragmatic hypermetabolic lymph nodes and multiple bone involvements. The patient opted for brentuximab vedotin plus combination chemotherapy. This case underscores the importance of exhaustive investigations and clinicopathological corroboration in the workup of hypereosinophilia.