An uncommon cause of unexplained nonbloody diarrhea: When mind knows eyes may see

Collagenous colitis (CC) is characterized by chronic secretory diarrhea with the apparently normal gross appearance of the colonic mucosa. A biopsy is usually diagnostic. The symptoms of CC appear most commonly in the elderly. In CC, the major microscopic characteristic is a thickened collagen layer beneath the colonic mucosa. The reported case represents unexplained nonbloody diarrhea of a systemic lupus erythematosus patient, on extensive evaluation found to have CC. This case highlights the importance of considering a rare possibility of CC as a differential in a patient of unexplained nonbloody diarrhea