A Case of SAPHO Syndrome: Clues in the Palm of the Hand

A 67-year-old woman with history of pustular psoriasis, type 2 diabetes mellitus, and hypertension presented to the hospital with a 4-month history of progressive sternal swelling and pain. She also reported wrist stiffness, which was worst in the morning and slowly relented in subsequent hours. She denied fevers, weight change, night sweats, dyspnea, dysphagia, orthopnea, and paroxysmal nocturnal dyspnea. She had no recent history of a dental procedure, bacteremia, or intravenous drug use. She reported having had moderate to severe acne as a teenager.

On physical examination, the woman was afebrile with stable vital signs. She exhibited swelling over her superior sternum (Figure 1) and pain with palpation over her manubrium and angle of Louis. Additionally, sternoclavicular pain was elicited with abduction and forward flexion of both shoulders. Cardiovascular, pulmonary, and abdominal examination findings were normal. Inspection of her palms and soles revealed deep-seated pustules (Figures 2-4), which she reported had been present for years. No other cutaneous manifestations were present.

Laboratory investigations revealed normal serum electrolyte levels, normal kidney and liver function, and normal hematologic indexes. Cardiac enzyme test results were negative for myocardial injury. Notably, the patient’s erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were elevated to 70 mm/h and 1.18 mg/dL, respectively. HLA-B27 assay results were negative.

A computed tomography scan with contrast of the thorax demonstrated inflammatory stranding, hyperostosis, and sclerosis of the manubrium with underlying reactive lymphadenopathy (Figure 5).

Initial consideration of the possible presence of osteomyelitis prompted combined blood cultures and percutaneous bone biopsy, both of which yielded sterile results. A diagnosis of SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome was made.

NEXT: DISCUSSION

Discussion

SAPHO syndrome was first described in 1987 by Charmot and colleagues,¹ who connected the constellation of synovitis, acne, pustulosis, hyperostosis, and osteitis. Kahn and Kahn² later outlined the diagnostic criteria for SAPHO syndrome in 1994 as follows:

• Multifocal osteitis with or without skin symptoms
• Sterile acute or chronic joint inflammation with pustules or psoriasis on the palms or soles, acne, or hidradenitis
• Sterile osteitis and any one of the previously listed skin manifestations.

The presence of any one of the 3 preceding criteria is sufficient for diagnosis. Skin and bone lesions can present at different times in the course of the disease, leading to a diagnostic challenge for clinicians. Such difficulty accounts for the fact that SAPHO syndrome, once thought to be a rare disease, likely is underdiagnosed by clinicians.³

Dermatologic presentations can include palmoplantar pustulosis, severe acne (acne conglobata or acne fulminans), and hidradenitis suppurativa. Psoriasis is not traditionally included as a manifestation specific to SAPHO syndrome; however, the incidence of psoriasis in this population is higher than that of the general population.² Approximately 20% of patients with SAPHO syndrome do not develop skin lesions.⁴

Musculoskeletal symptoms classically include arthralgias related to hyperostosis and osteitis. These are frequently located in the anterior chest wall, including the sternoclavicular, manubriosternal, and costochondral joints.⁵ The axial skeleton is the second most commonly affected region, including the spine, pelvis, and long bones.⁶ Imaging studies to assess for osteoarticular involvement is necessary, and technetium Tc 99m bone scintigraphy can help detect the presence of anatomic abnormalities before they become apparent.⁷ The appearance of a “bull’s head sign” demonstrating increased tracer uptake in the sternocostoclavicular region has been reported as an effective diagnostic tool.⁶

The pathogenesis of SAPHO syndrome remains unclear and controversial. Proposed pathogenic factors include autoimmune inflammation, infectious etiologies, and genetic predispositions. On occasion, Propionibacterium acnes has been isolated from bone and joint biopsies, prompting a theory of chronic subacute infection and subsequent autoimmune inflammation.⁸ Additionally, some authors classify SAPHO syndrome in the category of spondyloarthropathies, noting a higher incidence of psoriasis and inflammatory bowel disease in patients with SAPHO syndrome compared with the general population.^4,9 Reports of genetic susceptibility, such as HLA-B27 inheritance, vary widely in the literature.^2,10

SAPHO syndrome typically follows a chronic course and may have periods of exacerbation and remission. Female gender, elevated CRP and ESR, anterior chest wall involvement, peripheral synovitis, and skin involvement at the onset of disease are all factors associated with a chronic course.⁴

The approach to treatment is supported by small studies with rather limited evidence. Several different treatment strategies reflect the various presumed hypotheses about the pathogenesis of the syndrome. Treatments have included antibiotics to target P acnes, nonsteroidal anti-inflammatory drugs, corticosteroids, sulfasalazine, and methotrexate to address overlap with the spondyloarthropathies.⁶ More recently, bisphosphonates and biologics such as infliximab and anakinra also have demonstrated success.^6,11

Our report highlights a classic case of SAPHO syndrome with involvement of the anterior chest wall. The woman has been evaluated by dermatology and rheumatology specialists, and she is initiating treatment with sulfasalazine while being considered for pamidronate. SAPHO syndrome is a prime example of how rheumatologic disease may masquerade as other systemic illness such as osteomyelitis. Accordingly, SAPHO should be considered in any patient with axial or chest wall osteomyelitis without risk factors such as intravenous access, surgery, or bacteremia.

Kevin Davidson, MD, is a fellow in the Division of Pulmonary Sciences and Critical Care Medicine in the Department of Medicine at the University of Colorado School of Medicine in Aurora.

Rebecca Bialas, MD, MPH, is a dermatologist at Palm Harbor Dermatology in Palm Harbor, Florida.

References:

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