Answer

Answer to last month's Clinical Quiz

Question:
This is an 84 years old lady. This slide illustrated the skin rash in her right breast fold. She complained of an itchy rash with mild soreness in both breastfolds and groins for the previous two weeks when she returned from a tour in South-east Asia. She had a similar rash on and off for few years, more noticeable in summer time. She did not use perfumes or antiperspirant on the body though she was a bit sweaty in hot climates. Her past health was good apart from mild hypertension. There was no history of diabetes mellitus or other atopic diseases.

Answer:
D. Intertrigo

Intertrigo is an inflammatory dermatosis involving the body folds, especially those of the submammary and genitocrural regions. Physical factors such as obesity, sweating, friction, incontinence and soiling by excreta may render the skin vulnerable to the effect of other agents. It is marked by slight itching and soreness and superficial mild erythema of the apposed surfaces. Secondary infection occurs rapidly and usually mixed organisms are involved e.g. Staphylococcoccus aureus, Proteus, E coli and yeasts are commonly cultured. Latent diabetes mellitus should be excluded in persistent cases and overtreatment can induce irritation or allergic contact dermatitis. Sometimes, flexural or inverse psoriasis or seborrhoeic dermatitis can closely mimick the condition though signs can be found in other area e.g. scalp and nails. Skin scraping for microscopic examination can easily exclude yeast infection and tinea corporis. Furthermore, small satellite pustular lesions at the peripheral of the rash will be more typical for cutaneous candidiasis and an advancing edge with central clearing of the rash will be suggestive of ringworm or tinea infection. Contact dermatitis is differentiated by detailed history. Erythrasma is a chronic, localised superficial infection of the skin caused by Corynebacterium minutissimum. It can be detected by Wood's light examination under which there was coral red fluorescence. The border of the rash is sharply marginated with red colour at first and becomes scaly and brown later. It responds well to a course of erythromycin.

The winner of the December 2001 Clinical Quiz is
Dr. Lam King Hei, Stanley