Description

MYH-Associated Polyposis (MAP) is an autosomal recessive disorder with a high risk of colorectal cancer. Current recommendations provide guidance for endoscopic surveillance without recommendations for advanced imaging. This can be complicated in the cases of MAP due to its Lynch-like predisposition for extraintestinal malignancies.

A 62-year-old man with a history of MAP and Montreal L3B3P MYH-associated polyposis and Crohn’s disease in remission presented with fever, leukocytosis, and encephalopathy. MRI of the brain ruled out cerebral vascular accident and further infectious work-up was negative. Due to persistent fever and leukocytosis, a CT abdomen/pelvis with contrast was pursued, which revealed a 14 cm complex cystic mass originating from the cecum and invading the right iliopsoas muscle (Figure 1A) and anterolateral abdominal wall (Figure 1B). MRI with contrast (Figure 1C) demonstrated septated enhancement and other findings suggestive of mucinous malignancy; however, the patient’s colonoscopy from 12 months prior was negative up to the terminal ileum and thus the patient was treated with broad spectrum antibiotics for presumed abscess, without clinical improvement. Due to persistent symptoms, a repeat colonoscopy was performed, which revealed a fungating, obstructive mass; pathology remained negative for malignancy despite multiple biopsies. Due to high suspicion for malignancy, IR guided biopsy showed cells positive for CK20 and CDX2, negative for CK7 and TTF-1, consistent with tubular adenocarcinoma. He subsequently underwent a diverting loop ileostomy.

This was a rare and unfortunate case where the coexistence of MAP and ileocolonic CD in remission developed into colonic mucinous adenocarcinoma despite routine endoscopic surveillance. There are current guidelines of surveillance for MAP associated malignancy every 1-3 years from the age of 18-20, but his malignancy escaped detection. This underscores the potential utility and importance of incorporating advanced imaging techniques as part of surveillance for those who had multiple risk factors for developing gastrointestinal malignancies.

Figure 1: