Polypoid Histiocytoma (Fibroxanthoma) of the Stomach Mimicking Signet Ring Adenocarcinoma by Endoscopic Evaluation

Abstract

A 3 cm polyp of the gastric greater curvature formed by a histiocytoma (fibroxanthoma) was discovered in a 62-year-old, diabetic, chronically-ill woman undergoing evalua tion for anemia. The histology of the endoscopic biopsy of this lesion mimicked a signet ring adenocarcinoma as the mucosa was infiltrated by histiocytic cells with enlarged, atypical nuclei and intracytoplasmic mucin. The patient died without clinical evidence of recurrence from staphylococcal septicemia 8 months following subtotal proximal gastrectomy. While the pathologic findings fell into the spectrum of an in flammatory fibroid polyp or histiocytoma (inflammatory pseudotumor, plasma cell granuloma) of the stomach, the predominance of foamy histiocytes was distinctive. In addition, histiocytic cells were present in the enlarged perigastric lymph nodes, the spleen, and the bone marrow. The histogenesis of this gastric polyp is obscure and not the focus of this report. This polyp mimicked an adenocarcinoma by endoscopic evaluation both by its exophytic appearance and microscopic histology. Immunohisto chemistry for markers of epithelial and histiocytic differentiation may be used to avoid this diagnostic trap and establish the diagnosis prior to surgery. Int J Surg Pathol 2(2): 141-145, 1994