Diagnostic procedures of the skin. Part one: Wood's light, KOH slide, Gram's stain, and cultures.

The diagnosis of skin lesions involves the same priniciples and methodology required in other medical problems. Visual recognition alone and "shotgun" therapy is not a satisfactory clinical approach. A disciplined and careful examination of lesions, establishment of a differential diagnosis, and selection of appropriate procedures are frequently necessary for cutaneous diseases. The indications, limitations, interpretation, and techniques of diagnostic procedures must be well understoood to obtain reliable information. Not all tinea capitis will reveal fluorescence with Wood's light examination, but the Wood's light may be particularly helpful in the diagnosis of tinea versicolor, erythrasma, porphyria, and tuberous sclerosis. Bacterial growth on cultures taken from the skin does not necessarily mean infection. Because the eczematous skin teems with bacteria, there must be a careful interpretation of the cultures results within the context of the clinical situation. This paper is the first in a two-part series dealing with selected cutaneous procedures which are useful to the family physician in everyday practice.