Primary extramedullary plasmacytoma of the esophagus.

An uncommon manifestation of plasma cell neoplasia occurs outside the bone marrow and is designated "extramedullary plasmacytoma." These are usually encountered in mucosal sites of the head and neck region. The gastrointestinal tract may be secondarily involved in multiple myeloma or be the site of primary extramedullary plasmacytomas (PEMPs). The esophagus is the least common site of gastrointestinal PEMP. A 58-year-old man presented with dysphagia for solids over a period of 2 months. Otherwise, he was well and systemic examination did not reveal anything of note. After a nondiagnostic biopsy, the patient was subjected to esophago-gastrectomy. Gross examination of the esophagus revealed a large polypoid tumor. Histologically, it was composed of mature plasma cells, plasmablasts (some of which appeared anaplastic), and a minor admixture of lymphoid cells. Focally, the infiltrate permeated the squamous epithelium simulating lymphoepithelial lesions. The neoplastic cells were positive for epithelial membrane antigen, CD79a, IgG, and kappa, while the lymphoid cells were predominantly B cells. The patient did not have a monoclonal gammopathy. Skeletal x-rays and bone trephine examination were both normal. PEMP is biologically and prognostically different to other plasma cell neoplasms. Although rare, esophageal PEMP should be considered in the differential diagnosis of so-called undifferentiated malignant tumors of the esophagus.