Skin biopsy: Biopsy issues in specific diseases.

Misdiagnosis may result from biopsy site selection, technique, or choice of transport media. Important potential sources of error include false-negative direct immunofluorescence results based on poor site selection, uninformative biopsy specimens based on both site selection and technique, and spurious interpretations of pigmented lesions and nonmelanoma skin cancer based on biopsy technique. Part I of this 2-part continuing medical education article addresses common pitfalls involving site selection and biopsy technique in the diagnosis of bullous diseases, vasculitis, panniculitis, connective tissue diseases, drug eruptions, graft-versus-host disease, staphylococcal scalded skin syndrome, hair disorders, and neoplastic disorders. Understanding these potential pitfalls can result in improved diagnostic yield and patient outcomes.