궤양성 손톱주위염 양상으로 발생한 경성하감 1예

Syphilis is a highly contagious sexually transmitted disease, and early diagnosis and prompt treatment significantly affect the prognosis. Syphilis usually presents with genital lesions in the early stages; therefore, extragenital syphilitic lesions can easily be misdiagnosed. A 20-year-old man presented with a 1-month history of a worsening hyperkeratotic black crusted ulcerative plaque on the right 4th finger, with distorted periungual structures. Histopathological examination showed epidermal hyperplasia, mild endothelial swelling, and numerous plasma cells in the dermis. Excessive dermal infiltration of plasma cells suggested primary syphilis, which necessitated additional serological tests; the patient showed positive results on Venereal Disease Research Laboratory and Treponema pallidum hemagglutination testing. The lesion significantly improved after an intramuscular injection of 2.4 million units of benzathine penicillin G. We report a rare case of primary syphilis involving the finger in a patient with clinical features of ulcerative paronychia. (Korean J Dermatol 2021;59(1):67∼69)