Skin Disorders Guide

Diagnostic Hallmarks

1. Distribution- hands, arms, legs, and scalp
2. Marked tendency for clustering
3. Lack of response to antibacterial therapy
4. Potassium hydroxide (KOH) preparation and fungal culture

Clinical Presentation

The dermatophyte fungi Microspar’um canis, Trichophyton rubrum, T mentagrophytes, and T. verrucosum may cause a perifollicular abscess that is clinically characterized by the presence of follicular pustules. All of these organisms except T. rubrum cause sharply marginated, markedly inflammatory plaques on which the pustules are situated. These pustule-studded plaques are rather easily recognized as the inflammatory forms of tinea capitis, tinea barbae, or tinea corporis.

Perifollicular pustules resulting from T rubrum infection are somewhat harder to recognize. They occur in two settings. First, women with tinea pedis may, in the course of shaving their legs, implant Truman into traumatized follicles. This results in the appearance of scattered but grouped pustules on a corporis results in the development of grouped follicular pustules even while the erythema that ordlinarily accompanies such lesions is minimized by the inti-inflammatory effect of the steroids. Such lesions are most often encountered on the face and dorsal surface the lower legs. Second, the erroneous use of topical steroids oil plaques of ordinary tine of the hands where they are all too regularly misdiagnosed as bacterial folliculitis. Their fungal etiology is often not suspected until the clinician is surprised by the failure to respond to antibacterial treatment.

A clinical diagnosis of fungal folliculitis should be confirmed by KOH preparations and fungal culture . Fungal hyphae may be recognized on regular biopsy specimens if a periodic acid-Schiff stain is requested.

Course and Prognosis

Folliculitis resulting from T. rubrum continues its chronic low-grade course indefinitely unless treated. Slow peripheral extension occurs even while the central area heals. Fungal folliculitis resulting from the other, zoophilic organisms eventually resolves spontaneously.

Pathogenesis

Fungal folliculitis is caused by the dermatophyte organisms. Implantation is usually preceded by minor trauma to the skin.

Therapy

Griseofulvin or, possibly, ketoconazole should be used in the treatment of fungal folliculitis. There is some response to the use of topical antifungal agents, but complete clearing does not reliably occur. During the course of therapy, trauma to the infected skin should be avoided. Women who shave their legs should be advised to use a chemical depilatory during treatment.