Recurrence of an erythrodermic mycosis fungoides as a biologically indolent anaplastic large T‐cell lymphoma initially misdiagnosed as being of donor origin.

This article discusses the case of a 50-year-old woman who was initially misdiagnosed with cutaneous T-cell lymphoma (CTCL) but later diagnosed with posttransplant primary cutaneous anaplastic large cell lymphoma (pcALCL) after undergoing a stem cell transplant. Molecular studies revealed a common clonal origin of both lesions. The article emphasizes the importance of accurate diagnosis and highlights the potential for donor-origin T-cell lymphomas in stem cell transplant recipients. It also suggests the use of additional molecular studies for diagnosis and notes that the prognosis for posttransplant CTCL varies. [Extracted from the article]