45. Acute presentation of mycobacterium avium-intracellulare

Abstract

Background Mycobacterium avium-intracellulare is primarily a pulmonary pathogen that tends to affect immunocompromised hosts. Transmission may occur via inhalation or ingestion. Cases of mycobacterium avium-intracellulare causing non-specific abdominal pain have been well described in the literature. Only one case report however is presented where mycobacterium avium-intracellulare was thought to be responsible for a bowel perforation, this in an HIV positive patient on HAART. We present a case of a non-HIV infected patient presenting with bowel perforation secondary to transmural infestation by mycobacterium avium-intracellulare. Case presentation An 83-year-old female with a complicated history of polyarteritis nodosa and renal transplantation for severe necrotising crescenteric glomerulonephritis, presented with generalised abdominal pain, loose stools and vomiting. On examination, she was found to have generalised abdominal tenderness. Abdominal X-ray demonstrated free air under the diaphragm and bowel wall thickening in the right lower quadrant. At laparotomy, a perforated segment of jejunum was resected. The resection specimen showed a stellate shaped area of mucosal flattening with central ulceration. Histological examination demonstrated perforation associated with an extensive transmural infiltrate of histiocytes containing basophilic rod shaped organisms, which were further highlighted by Ziehl-Neelson and Wade-Fite histochemical stains. PCR for atypical mycobacterium was positive. Conclusion 1. Mycobacterium avium-intracellulare infection presenting as bowel perforation is uncommon. 2. The two main histological differentials to consider in the small bowel are Whipple's disease and signet ring cell carcinoma. 3. The Tropheryma whippleii organisms are non acid-fast and gram positive on histochemical staining. PCR is also useful to confirm the diagnosis. 4. The distinction from a carcinoma can be based on careful histological examination and immunohistochemical markers.