Signet Ring Cell Primary Cutaneous CD30+ Lymphoproliferative Disorder Presenting as a Monomorphic T-Cell Posttransplant Lymphoproliferative Disease

T-cell posttransplant lymphoproliferative disorders are rare, with peripheral T-cell lymphoma not otherwise specified being the most common type. Although cases of the signet ring cell variant of primary cutaneous CD30+ lymphoproliferative disorder have been reported, such cases have not been described in the posttransplant setting. We describe a case with emphasis on the special contextual differential diagnostic considerations.