A 16-year-old woman presented with complaints of severe pain in the sternum, between the shoulder blades and deep in the lower back for 3 months, especially in the morning and at rest.
Examination findings
Pressure pain could be triggered at the sternum and in the middle thoracic spine area. The spine mobility was reduced. A psoriatic-like squamous skin lesion was found on the right lower leg. The BSG was increased to 20/44 mm. There was a minor iron deficiency anemia. The other laboratory findings were within the normal range. HLA-B27, RF, ANA, ENA, dsDNA-AK, p/s-ANCA and ACE were negative.
Radiological findings
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Normal appearance of the thoracic and lumbar spine on X-ray, while CT shows an erosion defect at the impressed ground plate of T4.
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In MRI, T2-weighted hyperintense lesions are found at BWK 4 and 11 as well as LWK 1 and 5, with contrast-enhancing foci at the ventral vertebral body edges, surrounded by bone marrow edema (“shiny corners”). BWK 4 shows a disc impression.
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There is a band-shaped osteolysis with marginal sclerosis on the sternal body.
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Both sacroiliac joints are unremarkable.
Which diagnosis is the most likely?
Diagnosis: SAPHO syndrome
The diagnosis is made on the basis of the psoriatic skin lesions together with the radiological findings. The differential diagnosis includes chronic recurrent multifocal osteomyelitis (CRMO).
Therapy and course
First, a course of NSAIDs (up to a maximum of 3 x 800 mg/day ibuprofen) was started for 6 weeks, then decreasing doses of sulfasalazine were given for 4 ½ months. After six months, the patient was in complete remission. She has been free of symptoms for years and is once again taking part in competitive sports.
Background information
The acronym “SAPHO” describes the key symptoms of “Synovitis”, “Acne”, “Pustulosis”, “Hyperostosis” and “Osteitis”. The term “Skibo disease” (skin and bone) is also derived from the heterogeneous coexistence of skin and bone findings. The disease is an autoinflammatory disease associated with cutaneous involvement and chronic non-bacterial osteomyelitis. The diagnostic criteria are:
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multifocal sterile osteomyelitis with or without pustular skin disease,
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arthritis and pustular dermatosis, and
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osteomyelitis and pustular dermatosis or psoriasis.
The following forms of SAPHO syndrome are distinguished:
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chronic recurrent multifocal osteomyelitis (CRMO) in two-thirds of cases,
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spondyloarthritis hyperostotica pustulopsoriatica in almost one-third of cases (pustulosis palmoplantaris, sternoclavicular hyperostosis, spinal lesions) and
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rarely abortive forms (ACW syndrome = anterior chest wall syndrome, SCCH = sternoclavicular hyperostosis, acne-CRMO, acne-spondylitis).
Chronic recurrent multifocal osteomyelitis (CRMO) usually manifests outside of SAPHO syndrome with synchronous or metachronous osteomyelitis at the metaphyses of the long bones, at the thoracolumbar vertebral bodies and clavicles. Pustulosis palmoplantaris is present in 60% of cases. Pathogens usually cannot be isolated; anaerobic, hypovirulent skin germs are discussed as the cause.
Whether SAPHO syndrome should be classified as a seronegative spondyloarthropathy is a matter of controversy. The spondylarthropathy group comprises these entities:
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ankylosing spondylitis (Bechterew's disease),
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psoriatic arthropathy,
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enteropathic arthritis (Crohn's disease, ulcerative colitis),
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reactive (post-infectious) arthritis and
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undifferentiated spondyloarthritis.
Learning points
In cases of multifocal joint and spinal lesions, the history should be extended to cover evidence of skin involvement. Inflammatory lesions of the skeletal system are often detected earlier by MRI than by radiography. Imaging plays an important role in early diagnosis of inflammatory skeletal diseases.
