The clinical spectrum of PASS syndrome in hidradenitis suppurativa: findings from a systematic review

PASS syndrome is a rare autoinflammatory condition defined by the coexistence of pyoderma gangrenosum (PG), acne vulgaris, hidradenitis suppurativa (HS), and spondyloarthritis (SpA). First described in 2012, it has a chronic, relapsing course and belongs to a broader group of syndromes combining skin and musculoskeletal inflammation, such as: SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis), PAPA (pyogenic arthritis, PG, acne), PAPASH (PG, acne, HS), or PsAPASH (psoriatic arthritis, PG, acne, HS). A systematic review was performed on March 2026 according to PRISMA-S guidelines. Seven studies were identified with 12 patients (75% male, mean age 25 years). All patients presented with the four core features of PASS syndrome: PG (mainly affecting the lower extremities; upper extremities in 33.3% of cases), acne (including acne conglobate in 41.7% of cases), HS (mostly Hurley stage III, predominantly axillary and inguinoperineal), and SpA (predominantly axial, 75%). Laboratory findings often included elevated CRP (100%), ESR (80%), leukocytosis (60%), and fever (41.7%). HLA-B27 was positive in 33.3% of cases in which HLA-B27 testing was performed. All patients received biological therapy, most commonly targeting TNF (infliximab, adalimumab), followed by IL-1 (anakinra) and IL-17 A (secukinumab). Additional therapies - such as antibiotics, corticosteroids, methotrexate, sirolimus, or surgery - were required in 41.7% of cases. In summary, PASS syndrome is a rare, multisystem condition requiring multidisciplinary care. Targeted biological therapy is effective, although adjunctive treatment is often necessary.