Atypical blood and bone marrow lymphocytes in ALK-positive anaplastic T-cell lymphoma: important lessons

A 42-year-old man presented with a short history of fever, significant weight loss and bilateral neck swelling. A CT scan revealed widespread lymphadenopathy and hepatosplenomegaly. Lymph node morphology and immunohistochemistry confirmed a diagnosis of anaplastic lymphoma kinase (ALK)-positive anaplastic T-cell non-Hodgkin's lymphoma. Both the peripheral blood (PB) and bone marrow (BM) revealed atypical lymphocytes with cleaved nuclei, vacuolation and granulation, suggestive of disease involvement at both sites. However, BM and PB immunophenotyping and immunohistochemistry did not reveal typical markers (ALK and CD30) at either site. All features resolved with a short remission after conventional chemotherapy. Despite salvage chemotherapy and an autologous stem cell transplant, a relapse of the PB and BM features with stable radiological findings was noted. Rapid decline followed with pancytopenia resulting in death 12 months after the initial diagnosis.