Sexually Transmitted Diseases: Recognizing Telltale Skin Lesions Chancroid

A 32-year-old man had a 3-day history of a painful erosion on the penis accompanied by extremely tender "swelling" in the groin. He admitted to multiple episodes of unprotected sexual intercourse with prostitutes during the past month.

Physical examination revealed a 0.75-cm ulceration of the distal foreskin that was notably tender on palpation, and a 3.5-cm erythematous, tender, and fluctuant inguinal lymph node (A).

The working differential diagnosis included primary syphilis, chancroid, herpes progenitalis, and granuloma inguinale. The presence of pain and tenderness favored chancroid and herpes; the fluctuant node and lack of antecedent blisters suggested chancroid.

A serologic test result for syphilis (rapid plasma reagin) was negative, and a dark-field examination of the ulcer exudate failed to disclose spirochetes. A herpes culture was likewise negative. The enlarged lymph node was aspirated (B), and the acquired material was sent for culture. The patient was given oral erythromycin, 2 g/d. The grossly purulent nodal aspirate, as well as a specimen obtained by swabbing the ulcer base, grew abundant Haemophilus ducreyi, the causative organism of chancroid. All signs and symptoms cleared after 7 days of therapy.

Although relatively uncommon in the United States, chancroid is a frequent cause of infectious genital ulceration worldwide. Epidemics of this disorder have appeared intermittently in North America, and this patient proved to be the first of about 30 cases seen during the ensuing several months. Diagnosis is based on the exclusion of lues and herpes, and by demonstration of the causative organism on culture. However, many strains prove difficult to isolate on standard media and require enriched chocolate agar with vancomycin added to suppress contaminant overgrowth. Oral erythromycin and intramuscular ceftriaxone are the drugs of choice.

(Case and photographs courtesy of Ted Rosen, MD.)