Secondary syphilis mimicking sarcoidosis- A case report
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Syphilis has been reported to exhibit atypical clinical and serological courses in patients that are coinfected with HIV. Authors present a case report of secondary syphilis with skin rashes and renal dysfunction that mimics sarcoidosis due to atypical clinical and pathological presentations.

A 24-year-old heterosexual man with a recent diagnosis of HIV infection presented for his first HIV visit upon referral from his primary care physician. He reported a nonpruritic, nonpainful rash on the upper arms with progression to the face, bilateral upper thighs, and scrotum for 2 months. A biopsy of the skin rash from outside institution revealed non-necrotizing granulomatous inflammation consistent with sarcoidosis. He was treated with steroids for 1 week with no response.

Skin examination revealed indurated papules with a rubbery texture across the lower legs, upper thighs, arms, back, scrotum, soles of the feet, and perioral area. Occasional lesions were annular or macular with intermittent fine scales. As part of the routine evaluation of a new HIV-infected patient, rapid plasma reagin (RPR) test was performed and showed a titer of 1:512. Complete chemistries and metabolic panel were within normal limits other than elevated protein in the urine.

The patient was treated with one injection of Bicillin 2.4 million units. The initial skin biopsy was reviewed in our institution, and immunohistochemical stain for Treponema pallidum was then performed and positive. The skin biopsy block was also sent to CDC for T pallidum PCR test, which confirmed the diagnosis of secondary syphilis.

Full resolution of his rash was noted on follow-up visit. RPR titer decreased from 1:512 to 1:64 at 6 months post-treatment with no recurrence of skin lesions. His proteinuria resolved within 1 month after treatment.

Differential diagnosis of these two diseases is critical since the clinical courses and treatments are different. Highly clinical suspicion and utilization of confirmatory test in high-risk population is the key for the differential diagnosis.