Ulcerative colitis: a diagnostic odyssey through cutaneous polyarteritis nodosa and granulomatous hepatitis.

SummaryUlcerative colitis (UC), a chronic inflammatory bowel disease, can cause extraintestinal manifestations (EIMs) in approximately 40% of individuals. This case report discusses the diagnostic procedure of a woman in her 20s who initially had non-specific symptoms. The patient underwent a thorough evaluation, which initially pointed towards tuberculosis (TB) due to necrotic lymphadenopathy and granulomatous hepatitis. However, no microbiological evidence of TB was found, and her symptoms worsened despite antitubercular therapy. The patient developed painful nodular-ulcerative skin lesions consistent with cutaneous polyarteritis nodosa (cPAN) on biopsy. Eventually, a definitive diagnosis of UC was made, revealing the true nature of her multisystemic manifestations. Cutaneous vasculitis, including leucocytoclastic vasculitis and cPAN, is a rare EIM of UC, with only five reported cases in the literature. This case report highlights the clinical implications of EIMs and contributes to the expanding knowledge of rare EIMs such as cPAN and granulomatous hepatitis.