Papulosquamous eruptions: usefulness of biopsy in establishing diagnosis.

Papulosquamous dermatoses are caused by a variety of etiologic agents. T. rubrum in particular can produce clinicopathologic changes which mimic a spectrum of disorders. Of these, some are papulosquamos in character. Whenever patients are seen with atypical papulosquamous dermatoses, the clinical differential diagnosis should always include dermatophytosis caused by T. rubrum. If skin scrapings for direct microscopic examination and culture studies are negative, a biopsy should be seriously considered as the best procedure to aid in making the correct diagnosis. Periodically, tissue diagnoses of fungal disease are made by dermatopathologists when the problem has not even been suspected by the clinician. Clinicians and pathologists should maintain a high index of suspicion for the disease spectrum which T. rubrum can cause in the human host. T. rubrum represents a great mimicker of cutaneous diseases similar to eruptions caused by Treponema pallidum and drugs. Information T. rubrum and methods have been reported.