Bacterial infection stimulating granulocytic sarcoma of the small bowel

A 57-year-old white man who had abdominal pain and distension, died after a short hospitalization for increasing ascites, anorexia, and deteriorating mental status. At autopsy, the principal gross finding was a dilated, hyperemic, thickened proximal jejunum that by light microscopy consisted of a transmural infiltrate of large mononuclear cells. Intense naphthol AS-D chloroacetate esterase (NASD) positivity was observed within most of the cells, suggesting granulocytic sarcoma. However, bacterial strains and electron-microscopic examination revealed that the massive jejunal infiltrate was composed of macrophages containing numerous phagocytosed bacteria. Although occasional cells had primary and secondary granules characteristic of myeloid precursors present within their cytoplasm, most cells lacked specific granules. Attempts to reproduce this markedly enhanced NASD result experimentally in peritoneal macrophages of mice were unsuccessful. This case shows that intense NASD cytoplasmic staining may occasionally occur macrophages that have phagocytosed large numbers of bacteria.