Tropical infections and infestations
Infections constitute one of the biggest problems in dermatology in tropical countries of the developing world. Leprosy, for example, despite being a treatable disease, continues to ravage in many parts of the globe.
Leprosy
Clinical presentation
Tuberculoid leprosy affects the nerves and the skin. Nerves may be thickened, and anaesthesia or muscle atrophy is found. Skin lesions often occur on the face, and as few as one or two may be seen. They usually take the form of raised red plaques with a hypopigmented centre, which is typically dry and hairless (Fig. 1). Sensation may be impaired within the plaque.
The skin lesions of lepromatous leprosy are multiple and take the form of macules, papules, nodules and plaques. They are symmetrical and tend to involve the face, arms, legs and buttocks. Sensation is not impaired. Untreated, the condition is infectious from the nasal involvement. Progression gives a thickened furrowed appearance to the face (leonine facies) with loss of eyebrows (Fig. 2). Borderline leprosy shows features intermediate between lepromatous and tuberculoid.
Leprosy must be distinguished from a variety of other dermatological conditions (Table 1).
Table 1 Differential diagnosis of leprosy
| Type of leprosy | Differential diagnosis |
|---|---|
| Tuberculoid | Vitiligo, pityriasis versicolor, pityriasis alba, sarcoidosis, lupus vulgaris, granuloma annulare, post-inflammatory hypopigmentation |
| Lepromatous | Disseminated cutaneous leishmaniasis, yaws, guttate psoriasis, discoid lupus erythematosus, mycosis fungoides |
