Crohn’s Disease—Crohn’s disease infrequently involves sites outside the GI tract.19 Although oral,31 perineal, and perianal involvement in Crohn’s disease has been described, involvement of sites noncontiguous with the GI tract is rare.
Fourteen patients (including the present case) of CCD with penile involvement have been reported (Table).19-30 Eleven patients (79%) had concomitant perineal or perianal involvement; 8 patients (57%) noted fistula or sinus formation; 5 patients (36%) experienced cutaneous abscesses; and 2 patients (14%) had scrotal lesions.
Fistulas and perineal ulcerations are frequent complications (7/11 or 64%).32 CCD most commonly affects the lower extremities; however, genital, abdominal, and facial involvement also have been reported. Although Crohn’s disease frequently involves the small bowel exclusively (40%), all documented cases of CCD have arisen in patients with disease of the colon or rectum.32 A temporal correlation between the severity of bowel involvement and the presence of cutaneous lesions has not been observed.32
Histopathology results reveal a dermal infiltrate with noncaseating granulomas formed by aggregating epithelioid histiocytes and multinucleated giant cells. Lymphocytes and plasma cells often are present. Involvement of the fat produces a granulomatous panniculitis.33
The cause of CCD is unknown. Two theories have been proposed: CCD is a form of granulomatous vasculitis precipitated by sensitized T-lymphocytes reacting to a circulating antigen,34,35 or CCD may represent a granulomatous perivasculitis with inflammatory cells responding to cutaneous antigens.36 Immunofluorescence studies have suggested a T-lymphocyte–mediated type IV hypersensitivity reaction.20
Conclusion
Differentiating Crohn’s disease from PG may be difficult in sites that are potentially contiguous with the GI tract. Histologically, fibrinoid necrosis of dermal vessels may be present in both PG and CCD. However, CCD is more likely to demonstrate a granulomatous reaction as opposed to the sterile pyodermatous reaction seen in PG. CCD characteristically demonstrates persistent cutaneous fistulas and sinuses despite successful therapy to halt the inflammatory reaction in the bowel. Patients with CCD tend to be younger than patients with PG and have anal, perineal, or perianal involvement. Recurrent or persistent penile ulcers should be cultured for opportunistic pathogens. A biopsy should be performed to rule out other causes and to help differentiate these entities.