A variety of rheumatic diseases—systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and the vasculitides among them—manifest as “lumps, bumps, and holes” involving the extremities. Each of these diseases works through specific mechanisms on different structures of the skin to produce a distinctive pathology. In doing so, each provides clues to the cause, which the history and physical examination can help confirm.
Here we present a concise photoessay of those cutaneous manifestations that are commonly (but not solely) the presenting signs of SLE and RA. Skin biopsy is sometimes necessary for a definitive diagnosis; useful results depend on a technique that gives the depth necessary to see the pathology and on referral to an experienced dermatopathologist for the proper interpretation of biopsy specimens.
In a separate photoessay, we focus on relatively common manifestations of vasculitis and Behet's disease that involve the legs.
Systemic Lupus Erythematosus
An autoimmune rheumatic disease that may have multisystem involvement, SLE is associated with a variety of cutaneous manifestations that can occur on the lower extremities; these include erythema nodosum, lupus panniculitis, calcinosis cutis, antiphospholipid syndrome (with attendant thromboses and livedo reticularis), pyoderma gangrenosum, dermatofibromas, and, rarely, papulonodular dermal mucinosis.
Lupus panniculitis (Figure A) reportedly occurs in 2% of patients with SLE, most often in women aged 20 to 45 years, and can also develop in patients with cutaneous lupus erythematosus (LE).1 It is rarely found in children. Indurated nodules involving arms, buttocks, head, neck, and thighs are characteristic. Epidermal changes—including ulceration, erythema, and poikiloderma—may be present.1 More than 40% of patients present with overlying changes in the skin consistent with lesions of discoid LE.1 The differential diagnosis of lupus panniculitis includes Weber-Christian disease, cytophagic panniculitis, lymphocytoma cutis, lymphoma, traumatic panniculitis, factitial panniculitis, sarcoidosis, infectious cellulitis, and pancreatic panniculitis.1
Therapeutic options for lupus panniculitis include antimalarials and topical and oral corticosteroids.
Calcinosis cutis (Figure B) is another cutaneous manifestation of SLE. Note, however, that SLE is only one of the several diseases in which this dystrophic form of calcification can be observed. Rarely, calcinosis can occur in areas of discoid LE. This condition may manifest as nodules, plaques, or tumors composed of calcium salt deposits. The lesions are localized mainly on the extremities, in areas that are prone to trauma. They are managed with aluminum hydroxide, etidronate, and/or surgery.