Pyogenic Arthritis, Pyoderma Gangrenosum, Acne, Suppurative Hidradenitis (PA-PASH) Syndrome: An Atypical Presentation of a Rare Syndrome.

BACKGROUND Pyogenic arthritis, pyoderma gangrenosum (PG), acne, and suppurative hidradenitis (PA-PASH) syndrome has been linked to an auto-inflammatory pathway. We report a case that is an atypical presentation of a rare syndrome, which supports literature suggesting that different phenotypes of PG-related syndromes may be a variation of the same pathogenic spectrum. Interestingly, our patient displayed a positive proteinase-3 antibody (PR-3). The clinical relevance of this is unclear. In recent literature, antineutrophil cytoplasmic autoantibodies (ANCA) positivity has been reported in various inflammatory conditions other than ANCA-associated vasculitis (AAV). CASE REPORT A 44-year-old African American male with history of pyogenic arthritis, acne, suppurative hidradenitis, and chronic diarrhea presented for evaluation of painful ulcers located on the bilateral lower extremities, bilateral proximal interphalangeal joints, buttocks, and scrotum, and chronic diarrhea. Infectious etiologies for the ulcers were ruled out. Biopsy of an ulcer revealed PG. Colonoscopy revealed inflammation and ulceration with biopsy consistent with ulcerative colitis (UC). After treatment with prednisone, the ulcers healed within 4 weeks, and the chronic diarrhea resolved. CONCLUSIONS Our patient displayed a variation of PA-PASH syndrome and UC. Previously reported cases of similar phenotypes of PG-related syndromes have not presented in this fashion. Furthermore, the literature does not report cases of PG-related syndromes with an elevation in PR-3 antibody. Elevation in PR-3 has been reported in various inflammatory disorders aside from AAV. The relevance of this is currently unclear. It may be possible that the milieus of these various auto-inflammatory disorders may share pathogenic commonalities.