A Rare Case of Monomorphic T-Cell Posttransplant Lymphoproliferative Disorder Presenting as Primary Cutaneous...

Posttransplant lymphoproliferative disorders are a serious complication of hematopoietic and solid organ transplants secondary to iatrogenic immunosuppression. Most cases present as B-cell proliferations which are often Epstein-Barr virus positive; however, ∼10% of cases are T/NK cell and are less commonly associated with Epstein-Barr virus. Of these, cutaneous T/NK-cell lymphomas are exceedingly rare. We report a case of a 69-year-old male, liver transplant recipient who presented with a tender, bright red papule on the left arm during his annual skin cancer screening. Histopathologic evaluation revealed pleomorphic cells with enlarged nuclei, vesicular chromatin, and frequent mitotic figures, intercalating through the dermis. The tumor formed single strands and small cords without epidermal involvement. A patchy mild mixed inflammatory infiltrate was associated with the tumor. Tumor cells were CD2(+), CD4(+), CD30(+), CD3(-), CD20(-), ALK-1(-), and EBER(-). Molecular studies revealed a monoclonal T-cell receptor gamma gene rearrangement by polymerase chain reaction (PCR); ALK gene rearrangement was negative by fluorescence in situ hybridization (FISH). Taken together, the findings were consistent with an ALK-negative anaplastic large cell lymphoma involving skin, which, given the history of liver transplant, qualified as a monomorphic T-cell posttransplant lymphoproliferative disorder. Follow-up imaging studies showed no evidence of systemic disease, supporting an interpretation of primary cutaneous anaplastic large cell lymphoma.