Skin Biopsy Procedure

Standard Biopsy Sites

Therapath has established normal values for three biopsy sites. Taking a biopsy from these sites allows the neuropathologists at Therapath to provide a diagnosis by comparing the nerve fiber density of the patient against established normal values. If focal or compressive neuropathy is suspected, the biopsy can be done at the affected region and compared to the corresponding unaffected region as a control.

The 3 standard sites are:
T = Thigh, at the level of the pubis
C = Calf, 10cm above the lateral malleolus
F = dorsum of the Foot, over the extensor digitorum brevis muscle

Skin Biopsy Procedure

For a video of the procedure, click here.

Before performing the procedure, check the expiration date on the fixative vials (transport media) to ensure that it is viable. To review the contents of the biopsy kit, click here.

Make a 1 cm circle around the biopsy site. Clean the skin with an alcohol swab. Anaesthetize skin with 2% lidocaine with epinephrine, by injecting the edge of the circle, infiltrating but avoiding direct contact with the biopsy site.
The biopsy is performed using a 3 mm circular punch, at a depth of approximately 2 mm, or half the distance of the metal head of the punch tool. Push the tool with rotational motion and even pressure into the epidermis to the midpoint on the head of the punch tool.
Lift the edge of the biopsy with the anaesthetizing needle or forceps and free the biopsy from the attached underlying fatty tissue using forceps or scissors. Forceps should never contact the upper layer of the skin, but only the underlying tissue as it might destroy nerve fibers.
Place one sample in each vial of fixative and verify that the sample is floating before sealing the vial securely. Label the vials with the appropriate patient identifiers and body site location.

Ship samples back to Therapath the same day they are taken. For return instructions, click here.