The clinical triad of urethritis, conjunctivitis, and arthritis is observed in only 33% of patients with Reiter's syndrome. Thus many will not have evidence of prodromal enteric or urethral inflammation. Such patients are often designated as having "incomplete Reiter's" or "sexually acquired reactive arthritis." In the remaining individuals the diagnosis can be made by the presence of an acute, additive lower extremity oligoarthritis accompanied by extra-articular features. The earliest features of Reiter's syndrome most frequently appear within 1 to 4 weeks of a putative microbial exposure. Disease onset is usually heralded by the development of one or more of the extra-articular features. Early genitourinary tract involvement may be manifested as dysuria, urethral discharge, prostatitis in men, or cervicitis or vaginitis in women. Fever, malaise, fatigue, anorexia, weight loss, and ocular symptoms (e.g., conjunctivitis) are also common at the onset.

The arthritis is often the last feature to appear and is manifested as an acute asymmetrical or ascending inflammatory oligoarthritis. Involvement of the lower extremity (first metatarsophalangeal joints, ankles, knees, and toes) is most common. Upper extremity involvement is rarely present at the onset. However, with chronicity, upper extremity involvement may occur. Involvement of the toes and fingers may result in dactylitis, or the so-called sausage digit. Dactylitis is the net result of inflammatory changes affecting the joint capsule, entheses, periarticular structures, and/or periosteal bone.

Low back pain and other axial findings are present in up to 50% of individuals with Reiter's syndrome. However, radiographic evidence of sacroiliac or axial involvement is observed only with chronic and severe disease. About 20% of the most severely affected individuals demonstrate radiographic sacroiliitis.

EXTRA-ARTICULAR MANIFESTATIONS.

Extra-articular manifestations are frequently seen in Reiter's syndrome.Enthesitismost commonly affects the insertion of the Achilles tendon and/or plantar fascia on the calcaneus with resultant heel pain.Mucocutaneous featuresmay affect the genitourinary or gastrointestinal tract. Genitourinary involvement includes transient mucopurulent urethral discharge, urethritis, circinate balanitis, cervicitis, or vaginitis. Circinate balanitis appears as painless vesicles or large, shallow, serpiginous ulcerations or plaques on the glans or shaft of the penis. Painless lingual or palatal oral ulcerations may be seen in up to 50% of patients. Keratoderma blennorrhagicum is the most common of the cutaneous manifestations and is seen as a painless papulosquamous eruption frequently found on the soles or palms and uncommonly on the penis, trunk, extremities, or scalp(Fig. 287-5). Patients with chronic disease may demonstrate nail changes of onycholysis or subungual hyperkeratosis.Ocular manifestationsoccur early in the disease and include conjunctivitis, uveitis, and rarely, keratitis. Conjunctivitis tends to be bilateral, painful, and recurrent and lasts days rather than weeks. Acute uveitis is most often characterized by unilateral ocular pain.Other uncommon featuresmay include an asymptomatic conduction disturbance, prolonged PR interval, complete heart block, aortitis, aortic regurgitation, amyloidosis, central nervous system involvement, serositis, or pulmonary infiltrates.

Radiographic abnormalities in Reiter's syndrome are commonly seen in the peripheral joints, primarily in an asymmetrical distribution affecting the feet, ankles, and knees. The sacroiliac and hip joints are less frequently involved. Soft tissue swelling, juxta-articular osteopenia, joint space narrowing, and/or ill-defined erosions are seen. Areas of periostitis or reactive new bone formation are common, Although bilaterally asymmetrical sacroiliitis is common(Fig. 287-6), unilaterally symmetrical inflammatory changes or ankylosis has also been observed. Involvement of the lumbar spine differs from ankylosing spondylitis by the presence of non-marginal syndesmophytes or "bulky" osteophytes that are often unilateral or asymmetrical and tend to spare the anterior surface of the spine (seeFig. 287-3). Involvement of the cervical spine is uncommon in Reiter's syndrome.

Reiter's syndrome can usually be distinguished from rheumatoid arthritis (seeChapter 286)by evolution, pattern of involvement, associated extra-articular features, clinical course, and absence of serum rheumatoid factor. Reiter's syndrome should also be distinguished from septic arthritis (especially gonococcal arthritis), crystal-induced arthritis, sarcoidosis, and erythema nodosum on clinical grounds and after appropriate laboratory and synovial fluid analyses. It is more difficult to distinguish Reiter's syndrome from the other spondyloarthropathies and other reactive arthritides such as that seen withYersinia, Chlamydia,or acquired immune deficiency syndrome (AIDS)-associated reactive arthritis. In such instances, a diagnosis of Reiter's syndrome is made after a careful history, identification of extra-articular features, appropriate use of serologic testing, and most important, observation over time.

The prognosis and course of Reiter's syndrome are varied and unpredictable. The majority of patients have an initial episode usually lasting 2 to 3 months, but it may last up to a year. Recurrent attacks and prolonged disease-free intervals are common. A chronic peripheral arthropathy is observed in 20 to 50% of patients. These individuals have the greatest potential for axial progression and spondylitic changes. Death is rare and may be ascribed to cardiac complications or amyloidosis.