INCISIONAL & EXCISIONAL BIOPSIES
A skin biopsy refers to the removal of a sample of skin for diagnostic purposes and is usually undertaken with local anaesthesia.
Why have a skin biopsy?
A skin biopsy may be deemed necessary as part of the diagnostic process. The additional information obtained from the biopsy can help identify diagnostic clues that are invisible to the naked eye.
An incisional biopsy refers to the partial removal of a lesion for diagnostic purposes, and is typically carried out as a punch biopsy or as a larger ellipitical incision using a scalpel blade. For incisional biopsies, only a sample of the suspicious tissue is cut and removed for diagnostic purposes. Typically, the punch biopsy is the most commonly used and is performed using a disposable skin biopsy punch which ranges from 2–6 mm in diameter. The punch biopsy creates a full thickness sample of skin that allows the pathologist to get a good overview of the epidermis, dermis and subcutis at the same time. A suture is typically used to close a punch biopsy wound or help control bleeding.
An excision biopsy refers to the complete removal of a skin lesion, such as a mole or suspicious growth for both diagnostic and therapeutic purposes. Smaller lesions are most often removed using a scalpel blade as an ellipse, with primary closure using sutures. Larger excisions may be repaired using a skin flap or graft.
In addition, skin lesions protruding from the surface of the skin can be removed with a shave biopsy. This tangential shave of skin is taken using a special shave-biopsy instrument and no stitches are required. The wound forms a scab that should heal by itself in 1–2 weeks.
As a shave biopsy does not include the full thickness of the skin, the drawback of such a biopsy is that it may be difficult for a pathologist to identify invasive disease. Therefore, skin lesions deeper in the skin may need to have a sample taken using the punch biopsy or excision technique.