This patient was known to have HIV with a low CD4+ count. He went on to have a rectal mucosal wall biopsy.
MACROSCOPIC DESCRIPTION: four pale tan tissue fragments 3mm each.
MICROSCOPIC DESCRIPTION: The sections show fragments of large bowel mucosa, some including muscularis mucosae. There is mild architectural distortion. There is a somewhat patchy moderate infiltrate of neutrophils and mononuclear chronic inflammatory cells, which is mostly superficial. There are a few neutrophilic microabscesses. Crypt epithelium focally contains apoptotic figures. No parasites are seen. There is no evidence of malignancy.
CMV immunohistochemistry reveals small numbers of positive staining cells, focally in clusters. Overall the features are in keeping with a diagnosis of CMV PROCTITIS.
FINAL DIAGNOSIS: Focal active CMV proctitis.