- What are indications for skin biopsy?
- What is the cutaneous nerve/skin biopsy procedure?
- Can skin biopsy help confirm a specific diagnosis?
- What are the clinical indications or conditions which might benefit from a skin biopsy?
- Who interprets the results?
- What is immunohistochemistry?
- Is there a doctor or technician with whom I can directly communicate?
- Can I perform the biopsy in my office or does my patient need to come to Johns Hopkins?
- Once my patient is approved, what will I receive?
- How can I direct my patient to prepare?
- Is the biopsy painful?
- How should I look after the biopsy site?
- When can I expect the results?
- Are biopsies covered by insurance?
What are indications for skin biopsy?
A cutaneous nerve/skin biopsy is an easy and minimally invasive technique which permits the examination of the small sensory nerves in the skin. These are the nerves which conduct information about pain and temperature and are frequently involved in certain kinds of peripheral nerve damage (neuropathies). The skin biopsy allows for the identification of these nerves and an examination of their number and state of health. In general, when these nerves are affected by a peripheral neuropathy, the number and shape of the nerves is abnormal and can be recognized under the microscope.
What is the cutaneous nerve/skin biopsy procedure?
A cutaneous nerve/skin biopsy is a very simple procedure performed in the outpatient setting and takes 10 to 15 minutes. First, the skin is thoroughly cleaned and a small injection of a local anesthetic to numb the skin is made. Then, a sample of skin is taken by a biopsy from the numb area of the skin. Finally, a bandage dressing is used to cover the biopsy site. Generally, the skin heals easily within one to two weeks without the need for a suture. The risk of bleeding or infection is extremely low.
Can skin biopsy help confirm a specific diagnosis?
No. The changes in the small sensory nerves in the skin produced by peripheral neuropathies are relatively non-specific That is, different causes for peripheral neuropathy may produce identical changes. The skin biopsy is useful to diagnose the presence and stage the severity of a neuropathy, but usually cannot identify a specific cause.
What are the clinical indications or conditions which might benefit from a skin biopsy?
Neuropathies, which involve small sensory fibers, either predominantly or as part of a process which affects large and small nerve fibers, can benefit from skin biopsy diagnosis. Examples include:
- Diabetes mellitus
- Cancer chemotherapy
- HIV infection
- Toxic exposures to various drugs and chemicals
Unusual sensory syndromes with pain, tingling, itching, or burning may also be investigated with skin biopsy to identify whether there is a reduction in the density of small sensory fibers or a change in their shape (or morphology). Skin biopsy can also be used to differentiate radiculopathies (diseases which affect the nerve roots close to the spinal cord) from peripheral neuropathies (diseases where there is damage to or degeneration of the nerves in the periphery).
Skin biopsy has also been used to investigate:
- Post-herpetic neuralgia
- Alopecia ariata
- Freidriech ataxia (familial dysautonomia)
- Pots disease
- Congenital insensitivity to pain (hereditary sensory neuropathy type 4)
- Diabetic truncal neuropathy
- Notalgia paresthetica
- Atopic dermatitis
- Restless legs syndrome
- Fabry's disease
Skin biopsy has been used routinely because skin biopsy is so easy and minimally invasive, it can be repeated over time to examine the course or progression of a peripheral neuropathy, and in certain situations, to examine nerve fiber repair and regeneration.
Who interprets the results?
The results are interpreted by expert physicians at Johns Hopkins who are specially certified in neuromuscular pathology and are attending physicians in the Department of Neurology.
What is immunohistochemistry?
Immunohistochemistry is a powerful staining technique used by neurologists and pathologists to identify specific structures in tissue. Antibodies are developed which react against a structure of interest (in our case the small sensory nerves in the skin) and after coating the biopsy, these specific antibodies can be secondarily stained with a dye which can be recognized visually.
Is there a doctor or technician with whom I can directly communicate?
If you have any questions or concerns about the cutaneous nerve/skin biopsy, please contact us at 410- 614-6399.
Can I perform the biopsy in my office or does my patient need to come to Johns Hopkins?
Biopsies can be performed at physicians’ offices and then sent to the cutaneous nerve lab, or at the Johns Hopkins Outpatient Center or the Johns Hopkins Bayview Medical Center. In both situations, our staff will secure the patient’s insurance authorization once the appropriate referral forms have been completed. If a physician wants to perform the biopsy at his or her office, a biopsy kit can be mailed once the patient’s insurance authorization is obtained.
Once my patient is approved, what will I receive?
Once contacted, we will initiate insurance authorization and a biopsy kit will be shipped to the physician’s office. Step-by-step instructions with photographs will be included and video demonstrations are also available. The biopsy kit includes:
- Biopsy fixative
- Skin punch tool
- Scalpel and forceps
- Biopsy ID form
- Buffer and cryoprotectant solutions
- Printed instructions for obtaining biopsies and for cryoprotecting samples
- Wound care instructions to give to patient
- Shipping container and ice pack for return shipment (NOTE: Keep ice pack in refrigerator until use)
- Shipping instructions, including a pre-printed air bill for return shipment
How can I direct my patient to prepare?
The cutaneous nerve/skin biopsy is a relatively minor procedure. Patients should be informed that they will receive a local anesthetic prior to the biopsy. No other specialized preparation is necessary. Patients who are anticoagulated with an INR above 3.0 should not be biopsied.
Is the biopsy painful?
No. The biopsy itself is painless, although the injection of the local anesthetic before the biopsy usually produces a mild stinging sensation lasting a few seconds. After the biopsy, the skin heals rapidly within a few days and the healing site is almost never uncomfortable or painful.
How should I look after the biopsy site?
After the biopsy, you will be given detailed instructions about how to care for the healing biopsy site. It generally takes about a week for the biopsy to heal over and seal and thereafter the redness associated with the biopsy site will fade gradually over a few weeks or months.
When can I expect the results?
After the biopsy, a report will be sent to your physician within one to two weeks and they share the test results directly with you. The staff in the Johns Hopkins Medicine Cutaneous Nerve Laboratory is not permitted to give out results or otherwise discuss the biopsies directly.
Are biopsies covered by insurance?
Our staff will obtain insurance authorization once the appropriate referral forms have been completed. For questions, please call 410-614-6399.