Reactive arthritis (Reiter syndrome)

Synonyms: reaktive Arthritis

By Dr. Pascal Bafteh · last updated 09/2026

Definition & Classification

• Classification: seronegative spondyloarthritis, often associated with psoriasis spectrum.
• Current Terminology: The eponym "Reiter's disease" is usually avoided due to Hans Reiter's Nazi past — "reactive arthritis" is preferred.

Etiopathogenesis

• HLA Association: HLA-B27 in 70–80% of patients.
• Mechanism: infectious-allergic reaction with cross-reaction to HLA-B27.
• Common Trigger Pathogens:
• Urethritic: Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma
• Enteritic: Yersinia enterocolitica, Salmonella, Shigella, Campylobacter jejuni
• Viral: HIV (Reiter's described as an HIV manifestation)

Classic Triad

• Classic Triad: Arthritis + conjunctivitis + urethritis (Can't see, can't pee, can't climb a tree).

Arthritis

• Clinical Presentation: asymmetric, primarily lower extremities (knees, ankles, feet), often oligoarticular.
• Spondyloarthritis-Typical Associated Manifestations:
• Enthesitis (tendon/ligament insertion inflammation, classically Achilles tendon / plantar fascia)
• Dactylitis ("sausage finger" / "sausage toe" — diffuse swelling of an entire finger/toe)
• Sacroiliitis with back pain, morning stiffness

Conjunctivitis / Uveitis

• Ocular Findings: bilateral conjunctivitis — can progress to anterior uveitis.

Urethritis

• Sterile urethritis with pain, burning, discharge — often more visible in male patients.

Skin Manifestations

• Balanitis circinata: annular-erosive plaques on the glans penis — pathognomonic.
• Keratoderma blennorrhagicum: psoriasiform hyperkeratosis on palms and soles.
• Psoriasiform plaques on trunk and extremities possible (psoriasis-like).
• Aphthae / oral involvement: painless mucosal ulcers on the palate / buccal mucosa.
• Onychodystrophy / Onycholysis similar to psoriatic nail.

Diagnostics

• History of preceding infection (1–4 weeks before onset).
• Laboratory: ESR / CRP ↑, ANA / RF / CCP negative (seronegative!), HLA-B27 (positive 70–80%).
• Urethral / Stool Pathogen Detection: Urethral swab + PCR (Chlamydia trachomatis), stool PCR / culture.
• Imaging: Joint ultrasound (effusion), MRI in case of suspected sacroiliitis, X-ray classically shows erosive changes only late.
• Ophthalmological consultation in case of suspected uveitis.

Differential diagnoses

• Psoriatic arthritis
• Secondary syphilis (lues II)
• Hand-foot-and-mouth disease
• Psoriasis vulgaris (plaque psoriasis)
• Palmoplantar psoriasis
• Dyshidrotic hand eczema (pompholyx)
• Generalized pustular psoriasis (von Zumbusch)
• Behçet's disease

Sources (selection)

1. AWMF S3 Psoriasis 2021

More inflammatory skin diseases

• Cheilitis granulomatosa (Miescher)
• Erythema annulare centrifugum (EAC)
• Erythema nodosum
• Graft-versus-host disease (GvHD)
• Granuloma annulare
• Cutaneous sarcoidosis
• Lichen planus
• Lichen sclerosus

Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.