Inflammatory and Malignant Uptake Along Crohn Perianal Fistula on 18 F-FDG.

Inflammatory increased metabolic activity was discovered in the left anal canal on an 18 F-FDG PET/CT scan performed for initial staging of anal squamous cell carcinoma in a patient with history of perianal Crohn disease. This increased uptake was due to a complex intersphincteric perianal fistula with supralevator extension, with a secondary, contiguous, superficial focus of squamous cell carcinoma at the anal verge that was identified on an MRI performed on the same day.