An Unusual Presentation of Pseudomembranous Colitis.

Pseudomembranous colitis, also called antibiotic-associated colitis, is caused by the gram-positive anaerobic bacterium Clostridium difficile (C.difficile) . The infection is common in elderly patients on chronic antibiotic use and in immunosuppressed patients. We report a rare case of pseudomembranous colitis in a 49-year-old male who presented with cramping abdominal pain, abdominal distension, and loose stools, without any pre-existing immunosuppression or chronic drug intake. The computed tomography (CT) picture was suggestive of fulminant ulcerative colitis and the patient underwent total colectomy in view of severe disease. This patient also had rectal bleeding caused by a bleeding pseudoaneurysm of the right internal pudendal artery, which posed diagnostic and therapeutic challenges. Embolization of the pseudoaneurysm was done in the post-operative period. Though the clinical and radiological pictures were suggestive of ulcerative colitis in our patient, this was disproved in the histopathological examination and by the negative serum anti- Saccharomyces cerevisiae antibodies (ASCA) testing. The presence of extensive pseudomembranous colitis in this patient masked the bleeding pseudoaneurysm of the internal pudendal artery, as bleeding is a common presentation in fulminant colitis, leading to a delay in the management of the pseudoaneurysm. Such a presentation was not reported in the literature to the best of our knowledge. Considering co-existent pathologies, especially in patients who present with an unobvious clinical picture, can prevent delay in the definitive diagnosis of these conditions.