When A Patient Presents With Malodorous, Macerated Feet

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By M. Joel Morse, DPM

A Guide To The Differential Diagnosis

   Conditions commonly included in the differential diagnosis are plantar warts and tinea pedis. Plantar warts typically have localized areas of hyperkeratosis and are often painful whereas athlete’s foot presents as pruritus between the toes and is not limited to pressure-bearing areas. 2 It is helpful to assess the condition of the nails. If there is onychomycosis present, tinea pedis is usually present as well.

   Hyperhidrosis. Unlike pitted keratolysis, hyperhidrosis is not a temporary condition. It must commonly occurs in the hands, armpits and feet. In these cases the most likely explanation is a genetic trait. 10

   The eccrine sweat glands are mainly concentrated in the palms of the hands and soles of the feet. These patients will sweat all of the time and occlusive footwear or wet environments are not a factor.

   Erythrasma. This superficial localized chronic skin infection is caused by Corynebacterium minutissimum. It presents where there are moist occluded intertriginous areas and frequently presents as asymptomatic chronic maceration with fissuring or scaling.

   Predisposing factors include: humid climate, poor hygiene, hyperhidrosis, obesity, diabetes, advanced age and an immunocompromised host. In some patients, this condition presents as a hyperkeratotic, white macerated plaque, especially in the fourth interspace. 1 There is no central clearing as one would see with tinea pedis.

   The most common site of involvement is the toe web spaces. When there is accompanying pruritus, irritation of lesions may cause secondary changes of excoriations and lichenification. In other areas, the lesions present as pink to red. One may notice that the lesions are covered with fine scales and they may be accompanied by fine wrinkling. The red color fades to brown. Wood’s lamp shows coral red fluorescence caused by coproporphyrin III. 11

   Superficial cutaneous candidiasis. This condition occurs more often in immunocompromised people and involves the very outermost layers of the skin. Healthy skin is quite resistant to candidal infection. Pruritus and irritation of the affected areas are the usual complaints. 12

   Dyshidrotic eczema. Also called dyshidrosis or pompholyx, dyshidrotic eczema is an intensely pruritic condition that affects the hands more often than the feet and the sides of the digits are more characteristically affected. It is characterized by the development of vesicular eruptions along the sides of the extremities or digits, and between the digits. Interdigital maceration and desquamation of the interdigital spaces often are present. 13

   In some patients, dyshidrotic eczema presents as symmetric crops of clear vesicles and/or bullae on the soles and the lateral aspects of toes. Many cases of dyshidrotic eczema are the result of an occult allergen causing an allergic contact dermatitis. 14

   Pseudomonal pyoderma. This superficial infection of the skin has a bluish-green purulence, a “grape juice” aromatic odor and a moth eaten appearance of the epidermis with macerated borders. It presents in the toe webs.

   Palmoplantar punctate keratoderma. With this condition, there is obvious thickening of the stratum corneum with scaling. This condition is usually inherited but it can be acquired. One may sometimes see hyperkeratosis with this condition. There is no associated infection of the skin.

   Basal cell nevus syndrome. This is an inherited disorder characterized by wide-set eyes, saddle nose, frontal bossing (prominent forehead), prognathism (prominent chin), numerous basal cell carcinomas and skeletal abnormalities. Skin manifestations include pits in the palms and soles as well as numerous basal cell carcinomas. 15

   Less common considerations in the differential diagnosis include porokeratosis, arsenic keratosis, tungiasis, yaws and keratolysis exfoliativa. 2

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