Answer to last month's Clinical Quiz

Question:

A 52 years old man presented with a scaling rash at left palm for one month. He also had subungual hyperkeratosis of left second to fifth finger nails and on-and-off scaling at toe webs for five years. Moreover, he had generalised vitiligo and a history of alopecia areata. He was otherwise well.

Answer: A. Tinea manuum

The patient had tinea manuum of the left palm, together with tinea unguium of left finger nails and tinea pedis. Skin scraping from left palm and nail clipping from left finger nails demonstrated Trichophyton rubrum on fungal culture.

Tinea manuum refers to the dermatophyte infection of palmar skin. Often only one hand is affected, together with pre-existing involvement of both feet ("one hand, two feet" syndrome). Sometimes the corresponding finger or toe nails are also affected. The commonest causative species responsible is T. rubrum and sometimes Epidermophyton floccosum may be responsible. There is diffuse scaling on one palm and fingers on the same side, with accentuation on flexural creases ("powdery filling-in"). The infection may also extend to the dorsal hand surface, producing the more typical appearance of ringworm.

Tinea manuum is often quiet and longstanding. The diagnosis can be confirmed by skin scraping for fungal elements and fungal culture. Its differential diagnoses include eczema, psoriasis, pityriasis rubra pilaris. Hand involvement in these conditions is usually bilateral. Keratoderma blenorrhagicum refers to the palmoplantar hyperkeratotic psoriasiform eruption occurring in Reiter's syndrome. Other features include an asymmetrical seronegative arthritis usually of lower limb joints and conjunctivitis.

As a result of the thick stratum corneum of the palm, topical treatment alone is seldom effective. To eradicate the source of fungus, it is important to treat the associated tinea pedis. Systemic therapy is usually required. Griseofulvin, itraconazole and terbinafine are all effective in this condition.