Question:

A forty-year-old gentleman who worked in a wet market attends for consultation. He wears rubber boots when he works. He complains of malodorous and sliminess of his feet which has been present for more than a year. They are not itchy and he has never noticed any blisters on his feet. On close examination of his soles, multiple tiny crateriform pits are visible

Pitted keratolysis is a superficial bacterial infection of the soles, toes and sometimes the palms. It is characterised by erythematous plaques with shallow pits. The causative organisms are corynebacterium, actinomyces, micrococcus and dermatophilus. Hyperhidrosis, occlusive foot wear and prolonged immersion of feet in water are contributing factors.

Diagnosis is clinical by its distinctive appearance, ruling out differential diagnosis such as tinea pedis and palmoplantar eczema. It is advisable to send skin scrapings for fungal study to investigate for tinea pedis. Vesicular palmoplantar eczema is characterised by deep-seated vesicles in an inflammatory background. Plantar warts grouped together (Mosaic warts) on the sole may look like pitted keratolysis at a glance. Careful examination on mosaic warts will found firm rough surfaced plaques and when pared will show thrombosed capillaries.

Treatment of pitted keratolysis comprises of antibacterial therapy and keeping the feet dry. Whitfield's ointment and topical erythromycin are very useful. Patients are advised to keep their feet dry and hyperhidrosis can be treated with 20% aluminum chloride solution.