Small cell variant of anaplastic large cell lymphoma diagnosed by a novel chromosomal abnormality t(2;5;3)(p23;q35;p21) of bone marrow cells.

Because of the rarity and the morphological variations, small cell variant of anaplastic large cell lymphoma (ALCL) represents a diagnostic challenge. Herein is reported a case of leukemic type of small cell variant of ALCL, in which the diagnosis was established by a cytogenetic analysis. The patient was a 23-year-old woman who presented with fever and leukocytosis with circulatory atypical lymphoid cells. The initial differential diagnosis on bone marrow trephine biopsy sections included viral infection and peripheral T-cell lymphoma unspecified. But a cytogenetic study on bone marrow cells indicated a novel complex translocation, t(2;5;3)(p23;q35;p21), which led to confirmation of anaplastic lymphoma kinase (ALK)-positive pleomorphic small to medium-sized cells scattered in bone marrow cells, on immunohistochemistry. ALK was distributed in both nuclear and cytoplasmic regions of neoplastic cells. The patient achieved complete remission after four courses of combination chemotherapy, and received autologous peripheral stem cell transplantation (auto-PBSCT) after two additional courses of combination chemotherapy, but relapsed 2 months after auto-PBSCT in the bilateral lung. Allogeneic stem cell transplantation led to a second remission. This case demonstrates the diagnostic importance of cytogenetic study for malignant lymphoma involving bone marrow.