ALK positive lymphohistiocytic variant of anaplastic large cell lymphoma in an adult

Background and Objectives. The lymphohistiocytic (LH) variant of anaplastic large cell lymphoma (ALCL) has, for a long time, been considered typical o f children and adolescents. The aim of this study is a detailed characteriz ation of a case of this peculiar ALCL subtype affecting an adult patient. Design and Methods. A 36-year old male presented with diffuse adenopathy an d systemic symptoms (high fever, anorexia, asthenia); a diagnosis of CD30()/ALK(+) ALCL, LH variant, was morphologically suspected and corroborated b y immunohistochemistry that was crucial for the definitive diagnosis and su btyping. Results, The neoplastic population consisted of cells highly variable in si ze and shape but more often isolated and largely obscured by st predominant reactive cellular infiltrate of histiocytes and plasma cells. The lymphoma cells exhibited a null non-B non-T antigenic profile, but reacted strongly for the Ber-H2/CD30, EMA, ALKc anti-TIA-1 monoclonal antibodies, The patie nt underwent chemotherapy plus bone marrow transplantation and, one year af ter diagnosis, he is well and in complete remission. Interpretation and Conclusions. Our findings provide additional evidence th at: a) ALK(+) lymphoma represents a single disease with a broad spectrum of morphology; b) clinicians and pathologists should be aware of the possible occurrence of LH variant of ALK(+) ALCL also in adults in whom a favorable response to therapy may be expected despite systemic disease and an aggres sive clinical presentation. (C) 2001, Ferrata Storti Foundation.