A small cell variant of ALK-positive, CD8-positive anaplastic large cell lymphoma with primary subcutaneous presentation mimicking subcutaneous panniculitis-like T-cell lymphoma

作者：Wang Endi^*; Papalas John; Siddiqi Imran; Stoecker Maggie; Rehder Catherine; Sebastain Siby; Burchette Jim; Huang Qin

来源：Pathology Research and Practice, 2011, 207(8): 522-526.

DOI：10.1016/j.prp.2011.06.002

• ALK-positive anaplastic large cell lymphoma
• Small cell variant
• Subcutaneous panniculitis-like T-cell lymphoma

ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) is an uncommon non-Hodgkin's lymphoma of T-cell origin, the majority of which express CD4 and show frequent pan-T-cell antigen loss. While most cases of ALK+ ALCL have the common pattern characterized by anaplastic morphology with hallmark cells, a less common but well-recognized variant with a small cell pattern may pose a diagnostic challenge. We report a case of ALK+ ALCL with small cell morphology and CD8 subset restriction in a 53-year-old male patient who presented primarily with multiple recurrent subcutaneous nodules with histopathologic features simulating a subcutaneous panniculitis-like T-cell lymphoma (SPTCL). The case was initially diagnosed as SPTCL but was reconsidered as ALK+ ALCL when the incidental finding of CD30 positivity on a subsequent biopsy prompted an ALK immunostain, which turned out to be positive in the neoplastic T-cells. The diagnosis of ALK+ ALCL, small cell variant, was then confirmed by detection of an ALK gene rearrangement by FISH analysis. This report highlights a case of ALK+ ALCL with a deceiving clinical and histopathologic presentation, and emphasizes the value of immunohistochemical panel studies and genetic tests in such cases to avoid diagnostic errors.

• 出版日期2011