Early post-transplant smooth muscle neoplasia of the colon presenting as diminutive polyps: a case complicating post-transplant lymphoproliferative disorder.

A 44-year-old woman, 3 years post-transplant for pulmonary sarcoidosis, developed abdominal pain and diarrhea 13 months subsequent to an eradicated diffuse large B-cell-type, post-transplant lymphoproliferative disorder (PTLD) of the cecal region. Endoscopic examination identified multiple pale tan 5-to-9 mm rubbery nodules of the transverse and right colon in an otherwise unremarkable mucosa. Histology was characterized by bland smooth muscle proliferations, focally pushing into the mucosa. Immunohistochemistry (IHC), in situ hybridization (ISH), and polymerase chain reaction (PCR) of the sampled nodules confirmed Epstein-Barr virus (EBV) infection of neoplastic cells. To our knowledge, this is the first reported case of EBV-related post-transplant lymphoproliferative and smooth muscle neoplasms (PTSN) having distinct tropism for the colon. Endoscopic features of early PTSN, which in this case presented as diminutive polypoid lesions, have not been described previously.