Primary gastric plasmacytoma: A rare cause of hypertrophic gastritis in an adolescent

Background: This report describes a 16-year-old patient with gastric rugal hypertrophy caused by a primary gastric plasmacytoma. She had a 3-moth history of nausea and burning abdominal pain. Radiographic studies showed giant rugal hypertrophy. Superficial endoscopic gastric biopsies showed mild inflammation with plasma cells to polyclonal origin in the mucosa. When symptoms persisted, she underwent laparoscopic full-thickness gastric biopsy. There was monoclonal plasma cell infiltration histologically diagnostic of plasmacytoma and inconsistent with Helicobacter pylori-associated mucosa- associated lymphoid tissue (MALT) lymphoma. There was no evidence for involvement of the bone marrow or regional lymph nodes. The tumor did not respond to radiotherapy, necessitating total gastrectomy. Methods: Blood samples were analyzed for interleukin (IL)-6 by enzyme-linked immunosorbent assay. Gastric biopsy and gastrectomy specimens were subjected to immunophenotyping for κ and λ light chains, CD45, CD20, and LN1 and to polymerase chain reaction analysis for herpes virus HHV8. Results: There was no elevation in circulating IL-6 levels, militating against a pathogenesis akin to that of Castleman's disease. There was no evidence for infection with the Kaposi's sarcoma-associated herpes virus HHV8, which has recently been found in patients with multiple myeloma. Conclusions: This diagnosis and the characteristics of the tumor are very unusual, if not unique, for a patient of this age. The diagnostic evaluation of this patient also demonstrates the importance of deep endoscopic or full-thickness biopsies in some children with hypertrophic gastritis. (C) Lippincott Williams and Wilkins, Inc.