Biopsy of lesion or skin - histology

Role

Standard skin biopsy histology (formalin-fixed, H&E-stained) remains the diagnostic gold standard for most inflammatory, neoplastic, and infective skin conditions where the clinical diagnosis is uncertain or histological confirmation changes management
Extremely common investigation across dermatology practice, from confirming suspected skin malignancy to characterising an undiagnosed inflammatory dermatosis

Biopsy technique should match the clinical question: punch biopsy (a full-thickness cylindrical sample) is standard for most inflammatory dermatoses and small lesions; shave biopsy is appropriate for superficial lesions but inadequate if depth assessment matters (e.g. suspected melanoma, where Breslow thickness is prognostically critical); excisional biopsy provides margin assessment and is preferred when malignancy is strongly suspected and complete removal is both diagnostic and therapeutic
Shave biopsy is generally inappropriate for a lesion where melanoma is a differential, since it can transect the lesion and prevent accurate Breslow thickness measurement - a frequently tested technique-selection point given how directly Breslow thickness determines melanoma staging and management
Biopsy site selection matters - choosing a representative area (e.g. the most infiltrated/active edge of an inflammatory lesion, or the most atypical area of a pigmented lesion) improves diagnostic yield compared with a poorly chosen sampling site

Histological diagnosis directly determines management - confirmed malignancy triggers staging/excision planning with appropriate margins; confirmed inflammatory dermatosis diagnosis guides specific topical/systemic treatment selection

Melanoma (Breslow thickness dependent on adequate technique), basal cell carcinoma, squamous cell carcinoma, inflammatory dermatoses requiring histological confirmation (e.g. distinguishing psoriasis from other papulosquamous conditions)
Matching biopsy technique to the clinical question (particularly avoiding shave biopsy when melanoma is a genuine differential) is essential - an inappropriate initial biopsy technique can compromise subsequent staging accuracy and may require a repeat, more invasive procedure

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