Answer to last month's Clinical Quiz

Question:

A 26 years old man complained of a non-itchy erythematous rash of his palms and soles for one month. There was also truncal and leg involvement. Two months ago, he had a genital ulcer which spontaneously subsided. On further questioning, he gave a history of venereal exposure three months ago. There was no joint pain. Otherwise he enjoyed good health and had no history of drug allergy.

Answer: D. Secondary syphilis

This patient had secondary syphilis, confirmed by positive syphilis serology (VDRL reactive at 1:16 dilution, FTA-ABS reactive 4+, TPHA reactive 2+). Secondary syphilis usually occurs 6-8 weeks after chancre. In about one-third of patients with early secondary syphilis, there is evidence of a present or past primary lesion. A generalised, symmetrical and non-pruritic erythematous papulosquamous rash, characteristically involving palms and soles, is present. Condylomata lata may develop at warm and moist area, like the perianal area, vulvae and under the breast. These lesions are moist and are highly infectious, as their serous discharge contains a large number of treponemes. Mucosal ulcerations (mucous patches, "snail-track" ulcers) may occur at genitalia and mouth. Generalised lymphadenopathy, patchy "moth-eaten" alopecia, and systemic upset like fever, malaise and anorexia may also occur.

The differential diagnoses of secondary syphilis are myriad. Drug eruption, pityriasis rosea, viral exanthem, infectious mononucleosis and erythema multiforme all need to be considered. Pityriasis rosea is characterised by the presence of a herald patch and the collarette of scales. Condylomata lata may be mistaken as haemorrhoids and condylomata acuminata. The circinate balanitis and keratoderma blenorrhagicum of Reiter's syndrome also need to be distinguished. Seronegative asymmetric arthritis, usually of lower limb joints, and conjunctivitis are other features of Reiter's syndrome. Tinea infection of palms and soles may bear a superficial resemblance but can be confirmed mycologically.

The clinical suspicion of secondary syphilis can be confirmed by dark ground examination of serous discharge from condyloma lata for the typical spirochaetes (Treponema pallidum). The serological tests for syphilis are always positive (with the possible exception of some HIV antibody-positive individuals). The treatment of choice is still penicillin. Procaine penicillin is used in the Social Hygiene Service, Department of Health. For patients who are sensitive to penicillin, oral tetracycline or erythromycin may be used. For details of the treatment regimens, please refer to the Recommendations in Case Management of Sexually Transmitted Infections (STIs) in Hong Kong 2002, published by the Social Hygiene Service, Department of Health: http://www.info.gov.hk/aids/chinese/publications/index.htm