Generalized maculopapular rash and fever

Diagnosis: Systemic lupus erythematosus

Our patient’s fever and rash were highly suggestive of either systemic lupus erythematosus (SLE) or secondary syphilis (the “great masquerader”).

Dermatologic findings occur in more than 70% of patients with systemic lupus erythematosus.

In addition to the joint tenderness revealed during the musculoskeletal exam, our patient had several nonspecific lupus findings on skin exam: malar rash, discoid rash on hands, subacute vasculitis (generalized rash), alopecia, and an oral ulcer; he also had the specific finding of chilblains vasculitis of the toes. Lab work and pathology results made the diagnosis clear. Lab work revealed leukopenia, an antinuclear antibody (ANA) result of 1:2560 with speckled appearance, and positive anti-SM antibodies. A dipstick was negative for protein; VDRL and treponemal antibodies tests were also negative. Histopathology showed perivascular lymph histiocytic vacuolar dermatitis with a differential of connective tissue disease, including lupus.

Our patient met the criteria

SLE is a systemic autoimmune disease resulting in chronic inflammation in multiple organ systems; it commonly manifests with vague symptoms of fatigue, fever, and weight loss. The prevalence of SLE in the United States has been reported as high as 241 per 100,000 people. ¹ Women are more likely to be affected, and the incidence is highest among Black people and lowest among Caucasians.^1,2 Risk factors include cigarette smoking and exposure to silica particulate air pollution.

The 2019 European League Against Rheumatism/­American College of Rheumatology criteria for a diagnosis of SLE require that a patient have a positive ANA and some, but not all, additive lab, clinical, and organ-specific findings.³ Findings that clinicians should look for include^3,4

• elevated ANA (≥ 1:80)
• constitutional symptoms (fever)
• hematologic findings (leukopenia, thrombocytopenia, autoimmune hemolysis)
• neuropsychiatric findings (delirium, psychosis, seizure)
• mucocutaneous findings (alopecia, oral ulcers, others)
• serosal findings (effusion, acute pericarditis)
• musculoskeletal findings (joint involvement)
• renal findings (proteinuria)
• antiphospholipid antibodies
• decreased complement proteins
• SLE-specific antibodies.

Dermatologic findings occur in more than 70% of patients with SLE.⁵ They can be nonspecific—eg, classic discoid rash, malar rash, alopecia, maculopapular rash (most commonly on sun-exposed areas, mimicking polymorphous light eruption)—or specific (eg, chilblains).⁵

Continue to: The differential for rash and fever is broad