Tinea manuum is frequently misdiagnosed because it appears similar to:
- Hand dermatitis - especially the type called pompholyx.
- Psoriasis - especially palmoplantar pustulosis.
- Keratolysis exfoliativa.
Clinical features of tinea manuum
Tinea manuum can occur as an acute inflammatory rash like tinea corporis. There is usually a raised border and clearing in the middle (ringworm). This is most likely when a zoophilic (animal) or geophilic (soil) fungus is responsible. The likely fungi are:
- Trichophyton erinacei - from a hedgehog
- T. verrucosum - from cattle
- Microsporum canis - from a cat or dog
- M. gypseum - from soil
More frequently, tinea manuum causes a slowly extending area of peeling, dryness and mild itching on the palm of one hand (hyperkeratotic tinea). Skin markings may be increased. Generally both feet appear similar ("one hand, two foot syndrome"). The usual cause is an anthropophilic (human) fungus:
- T. rubrum
- T. mentagrophytes var. interdigitale
- Epidermophyton floccosum
These fungi may also cause a blistering rash on the edges of the fingers or palm. The blisters appear in crops and contain a sticky clear fluid. They may have a peeling edge. This form of tinea manuum itches and burns.
Predisposing factors for tinea manuum
Tinea manuum results from:
- Contact with another site of infection, particularly the feet (tinea pedis) or groin (tinea cruris)
- Contact with another person with tinea
- Direct contact with an infected animal or soil
- Contact with a contaminated object such as a towel or gardening tool
Distinguishing features of tinea manuum
Tinea manuum can be distinguished from hand dermatitis:
- In most cases of tinea manuum, only a single hand is involved.
- If both hands are affected, involvement is asymmetrical.
- Increased skin markings can be seen in dermatitis but in chronic tinea manuum they are white because of surface scale.
- Involvement of both palm and back of hand in contiguity.
- The rash may have an elevated border.
- Nearby nails may also be infected (tinea unguium). However, other skin conditions can also affect nails.
Diagnosis of tinea manuum
The diagnosis of tinea manuum is confirmed by microscopy and culture of skin scrapings.