Simultaneous colonic T-cell lymphoma and graft-versus-host disease: A rare diagnosis

Cutaneous T-cell lymphoma (CTCL) presenting as mycosis fungoides is typically localized to the skin and occasional draining lymph nodes. We present a 46-year-old man with refractory CTCL status-post allogeneic stem cell transplant who was biopsied for diarrhea and abdominal pain. These gastrointestinal biopsies revealed not only graft-versus-host-disease but also a clonal atypical lymphoid infiltrate with the same morphology and immunophenotype as the patient’s known CTCL. We discuss the differential diagnosis of CTCL metastatic to the intestinal mucosa versus post-transplant lymphoproliferative disorder and present a review of the literature. This case demonstrates challenging diagnostic workups in limited tissue samples as well as critical clinical implications.