Abstract
Anaplastic large cell lymphoma (ALCL) is an uncommon T cell lymphoma with characteristic expression of CD30. There are two different subtypes of ALCL: primary cutaneous (C-ALCL) and systemic (S-ALCL). These subtypes have overlapping morphologic and phenotypic characteristics, but differ in gene rearrangements and prognosis. Based on the recent classification of skin tumors by the World Health Organization (WHO), most cases of S-ALCL are ALK positive and CD45 negative compared to C-ALCL which are usually ALK negative and CD45 positive. Herein, we present a case of a 73-year-old male with a 19-month history of ALK negative S-ALCL status post six cycles of chemotherapy who developed well demarcated pink papules and plaques involving his thigh, knee, leg, shoulder, arm and back. Histologic findings showed a diffuse dermal infiltrate of large, pleomorphic cells that were CD30 positive, CD45 positive and ALK negative. Although the immunohistochemical profile is more typically observed in C-ALCL, based on the patients clinical history, a diagnosis of ALK negative S-ALCL was rendered. We present this case to highlight the importance of obtaining a complete clinical history and physical examination before rendering a diagnosis of C-ALCL, as there are differences in management and clinical outcome between the two entities.
Financial Disclosure:
No current or relevant financial relationships exist.
