Benign signet ring cells in pseudomembranous colitis: a diagnostic trap

A 71-year-old female patient was admitted with intractable diarrhea and abdominal distention following several courses of broad spectrum antibiotic therapy. Colonic biopsy revealed pseudomembranous colitis with foci of signet ring cell (SRC) change. The SRCs possessed bland nuclei and were confined to the basement membranes of the crypts with no infiltration into the lamina propria. Benign SRCs in pseudomembranous colitis is an uncommon phenomenon. Awareness of this rare, but potential pitfall is of utmost importance to avoid a misdiagnosis of SRC carcinoma.