Background
A spectrum of diseases, mostly infectious or inflammatory conditions, can produce granulomas in the perianal region and perineum. Perianal granulomas present some degree of diagnostic difficulty, with standard histologic diagnosis often doing little to clarify their etiology. The treatment of these lesions varies from entity to entity.
A granuloma is a nodule consisting of mainly epithelioid macrophages. The nodule may also consist of other cells (eg, inflammatory, immune) and extracellular matrix. A granuloma is often surrounded by a lymphocyte cuff and fibrosis.
Granulomas can form when the immune system attempts to fend off and isolate an antigen, such as an infectious pathogen or a foreign body. In many cases, however, granulomas form without apparent cause in autoimmune disorders. Crohn disease (CD) is the most common cause of perianal granulomatous disease in Western nations.
Elsewhere, the incidence of non-CD perianal granuloma varies, but it may be more common than in the United States.
The incidence of perianal granuloma of non-CD etiology seems to be increasing worldwide, albeit more slowly in the Western world than in the developing world. Many of the infectious agents responsible are resistant to conventional therapy. Early diagnosis is nearly unknown. This group of diseases should be considered in the differential diagnosis whenever an unusual lesion is found in the perianal region or when no response occurs to conventional surgical treatment.
Knowledge of the anatomy of the male and female perineal floor, as well as of perianal anatomy, is required of the surgical specialist treating complications of perianal granulomatous disease. If the inflammatory process extends anteriorly, consultation with urologic or gynecologic specialists can be invaluable.
For patient education information, see the Digestive Disorders Center, as well as Crohn’s Disease, Inflammatory Bowel Disease, and Anal Abscess.