Pyoderma gangrenosum (PG) is an idiopathic, progressive, ulcerative skin disease. Half of all cases are associated with identifiable systemic diseases including arthritis,1 hepatitis,2 blood dyscrasia,3 and immunosuppression.4-6 PG is most frequently associated with inflammatory bowel disease (IBD).4,7
Crohn’s disease (regional enteritis) is a chronic, granulomatous, inflammatory bowel disease that may affect the entire gastrointestinal (GI) tract, as well as the skin. Draining sinuses or fistulas may form between the GI tract and contiguous skin. Cutaneous manifestations associated with regional enteritis include PG, erythema nodosum, and metastatic Crohn’s disease in noncontiguous skin.
There are several differential diagnoses that should be considered: (1) infections, such as Fournier’s gangrene, bacterial pyoderma, deep fungal infection, chronic herpetic ulcer, anaerobic erosive balanitis in uncircumcised men, mycobacterial infection, gummatous syphilis, and amebiasis cutis; (2) neoplastic conditions, such as squamous cell carcinoma, metastatic gastrointestinal or genitourinary carcinoma, extramammary Paget’s disease; and (3) miscellaneous conditions, such as metastatic Crohn’s disease, PG, erosive lichen planus, halogenodermas, necrotizing vasculitis, antiphospholipid syndrome, brown recluse spider bite, and factitial dermatitis. Differentiating between PG and cutaneous Crohn’s disease (CCD) may be difficult, as the clinical and pathologic features often are similar.
A 52-year-old circumcised white man was diagnosed with Crohn’s disease in 1974. The condition periodically was responsive to sulfasalazine, metronidazole, and prednisone. A small bowel resection was performed 1 and 10 years after the diagnosis; pathology showed mucosal thickening and cobblestoning confined to the small bowel and proximal colon. Histologic examination revealed inflammation of all layers of the intestinal wall and evidence of granulomas.
In January 1998, the patient developed a small nodule on the distal lateral shaft of the penis. The lesion ulcerated, and biopsies were performed. Histologically, the tissues showed epidermal spongiosis and ulceration with a mixed dermal inflammatory infiltrate containing numerous neutrophils, compatible with PG. Results of cultures and special stains (Gomori methenamine-silver, Brown-Brenn, Fite) were negative. The Crohn’s disease was inactive, evinced by a normal upper GI study in March 1998. However, the penile nodule ulcerated further and then remained under control on a therapeutic regimen of prednisone, amoxicillin, isoniazid, and sulfamethoxasole/trimethoprim.
In March 1998, a papule arose on the patient’s right thigh that soon became ulcerated. A biopsy revealed an inflammatory cell infiltrate with giant cells and palisading granulomas consistent with metastatic Crohn’s disease (Figure 1).
In January 1999, the penile lesion became increasingly erythematous, edematous, ulcerative, and painful. Burning developed with urination. The ulcer measured 3x2.5 cm with a depth of 1 cm and involved the distal lateral neck of the glans, corona, and glans penis (Figure 2). A violaceous rolled border was present inferiorly. The ulcer produced a sparse purulent exudate. No inguinal lymphadenopathy was discerned. A urethral fistula was discovered in March 1999.
Due to the refractory nature of the condition, immunosuppressive medications were considered. The patient refused cyclosporine, and mycophenolate mofetil 500 mg twice a day was initiated. The purulent drainage, urine leakage, pain, and induration experienced by the patient decreased in 3 weeks. Complete blood count, differential blood count, and electrolyte count test results were unremarkable. A second lesion arose on the left corona, and the mycophenolate mofetil was increased to 1 gm twice a day. Inflammation and pain again subsided.
With progression of the disease process and development of a fistula, characteristic of Crohn’s disease, a partial penectomy was subsequently performed, leading to resolution of the disease process.
Pyoderma Gangrenosum—PG presents as tender erythematous vesicles, pustules, or nodules that may ulcerate. The 4 types of PG recognized are vegetative, ulcerative, pustular, and bullous.8 Ulcerative PG begins as tender pustules that rapidly enlarge. Mature lesions have characteristic blue, rolled, undermined borders and are frequently surrounded by erythema. Classic ulcers are aseptic, though superinfection may occur. Healing results in an atrophic cribriform scar. The trunk and lower extremities are most frequently affected,4 but lesions also may occur on the upper extremities, head, and neck. Trauma and cutaneous compromise, including surgery, may precipitate or exacerbate lesions (pathergy phenomenon).
IBD is present in up to one third of patients with ulcerative PG.4,9 Conversely, PG occurs in 1.5% to 5.0% of patients with IBD.4 Ulcerative PG may occur before, after, or concurrently with IBD, and the condition typically demonstrates an independent course.8
A diagnosis of PG is made with clinical and pathologic correlation because the histologic features are not specific. In advanced lesions, histology shows epidermal necrosis and a mixed dermal infiltrate with prominent neutrophils. Late-stage PG can have a mononuclear cell infiltrate and scarring but little or no evidence of granulomas.10 Excluding other conditions is important (see differential diagnosis). Early recognition may avert surgical debridement, which may lead to increased tissue loss and disease progression (pathergy).11-14
Eight cases of penile PG have been reported (Table).11-18 The 2 associated diseases, chronic lymphocytic leukemia12 and ulcerative colitis,13 were present in 2 cases. The scrotum was affected in 4 cases (50%).12-15 One case had perianal involvement,13 and one case had a urethral fistula.16 It is likely the latter case was incorrectly diagnosed because fistula formation is a feature of Crohn’s disease, not PG.