Invasive intervention in a tissue, usually performed for diagnostic reasons. If indicated, a skin biopsy is performed under local anesthesia and sterile conditions. For smaller skin samples, the biopsy is generally performed using round punches (disposable punches, e.g. Stiefel; diameter 2-6 mm). When taking the biopsy, care must be taken to ensure that the tissue is not squeezed by the surgical procedure, otherwise histological evaluation will be impeded. This is especially true for biopsies in inflammatory dermatoses; tissue integrity is also important in the evaluation of cellular infiltrates ( lymphoma; lupus erythematosus; urticaria pigmentosa). As with any other surgical procedure, the patient must be informed of the benefits and potential complications before the procedure. Skin biopsies generally cut through the entire skin and leave scars! The correct selection of the biopsy site is crucial for histological interpretation; only clinically typical and fresh lesions are biopsied. In inflammatory dermatoses, pretreatment with glucocorticoids should be excluded in all cases; if such pretreatment existed, it must be discontinued for several days (> 7 days).
In addition to surgical biopsy, optical biopsy is also used in dermatology, see Laser scanning microscopy.