What condition is pyoderma gangrenosum typically associated with?

Pyoderma Gangrenosum is Most Commonly Associated with Ulcerative Colitis

Pyoderma gangrenosum is typically associated with ulcerative colitis (option c), occurring in 0.6-2.1% of ulcerative colitis patients. 1

Association with Inflammatory Bowel Disease

• Pyoderma gangrenosum (PG) is most commonly associated with inflammatory bowel disease, particularly ulcerative colitis, though it can also occur with Crohn's disease 2
• Approximately 50-70% of PG cases are associated with underlying systemic disorders, with inflammatory bowel disease being the most frequent association 2
• PG can affect patients with ulcerative colitis regardless of the severity of their bowel disease - it may occur even in patients with clinically mild colonic IBD 3

Clinical Characteristics

• PG lesions often begin as inflammatory pustules with surrounding halos that enlarge and ulcerate, presenting with undermined bluish borders and surrounding erythema 4
• Lesions are frequently preceded by trauma (pathergy phenomenon), explaining why they often occur post-surgically or adjacent to stomas 1
• PG most commonly affects the shins but can occur anywhere on the body, including the genitalia 2, 5

Relationship with Disease Activity

• The relationship between PG and ulcerative colitis activity is controversial - some cases parallel the intestinal disease activity while others run an independent course 1
• Unlike erythema nodosum (another skin manifestation of IBD), which typically correlates with disease flares, PG may persist or develop even when bowel disease is controlled 1

Treatment Approach

• First-line treatment typically involves systemic corticosteroids 1, 6
• For cases not responding rapidly to corticosteroids, infliximab should be considered, with response rates exceeding 90% in PG of short duration (<12 weeks) 1, 6
• Adalimumab is an effective alternative anti-TNF option for PG associated with ulcerative colitis 1, 6
• Topical or oral calcineurin inhibitors can be used as adjunctive therapy 1

Diagnostic Considerations

• Diagnosis is primarily clinical, though biopsy from the periphery of lesions can help exclude other disorders 2
• Histopathology typically shows a neutrophilic infiltrate confined to the dermis, but findings are non-specific 4
• PG must be differentiated from infectious causes, vascular disorders, and malignancies 2

Important Distinctions

• While PG is strongly associated with ulcerative colitis (option c), it is not typically associated with advanced colonic adenocarcinoma (option a), rectal carcinoid (option b), or villous adenoma of the colon (option d) 1, 2
• PG belongs to the spectrum of neutrophilic dermatoses that can occur with IBD, which also includes Sweet's syndrome and bowel-associated dermatosis-arthritis syndrome 1

Prognosis

• PG has a high recurrence rate of more than 25% following successful treatment, with recurrences often occurring in the same location as the initial episode 2, 6
• Healing typically results in characteristic thin, atrophic scars 4