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Test Code LABENFD Epidermal Nerve Fiber Density Consultation, Varies

Additional Codes

Test Name in EPIC EPIC Test Code Mnemonic Mayo Test ID
EPIDERMAL NERVE FIBER DENSITY CONSULTATION LABENFD ENFD SPBX

 


Shipping Instructions


Transport specimen per instructions on the Epidermal Nerve Fiber Density Preparation Instructions (T703).



Necessary Information


All requisition and supporting information must be submitted in English.

 

Each of the following items is required:

1. All requisitions must be labeled with:

-Patient name, date of birth, and medical record number

-Name and phone number of the referring pathologist or ordering provider

-Anatomic site and collection date

2. Epidermal Nerve Fiber Density Patient Information (T702)

3. Additional clinical information:

-Neurology clinical notes

-Electromyography results if performed



Specimen Required


Preferred:

Specimen Type: Skin punch biopsy

Supplies: Skin Punch Biopsy Kit (to order call either 507-284-8065 or 800-533-1710) containing fixatives, buffer, and cryoprotectant

Source: Distal leg, mid-thigh, dorsal foot, or lower abdomen

Container/Tube: A Skin Punch Biopsy Kit is required (no substitutions accepted) for collection.

Collection Instructions:

1. The standard biopsy for evaluating distal small fiber sensory neuropathy includes two 3-mm skin punch biopsies from the same side of the body.

2. Prepare specimen per instructions on the Epidermal Nerve Fiber Density Preparation Instructions (T703).

 

Acceptable:

Specimen Type: PGP 9.5-reacted slides

Additional Information:

1. At least one slide reacted with PGP 9.5, using a PGP 9.5 protocol for visualizing epidermal nerve fibers, is required.

2. At least one hematoxylin and eosin-stained slide and one Congo red-stained slide are optional.

 

Specimen Type: PGP 9.5-reacted slides and tissue block

Note: Visualization of epidermal nerve fibers cannot be done on paraffin blocks.

Additional Information:

1. At least one slide reacted with PGP 9.5, using a PGP 9.5 protocol for visualizing epidermal nerve fibers, is required.

2. Tissue block may only be used to create hematoxylin and eosin-stained slides and Congo red-stained slides.


Useful For

Investigating polyneuropathies

Disease States

  • Small fiber neuropathy
  • Polyneuropathies

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
SS2PC SpecStain, Grp II, other No, (Bill Only) No
COSPC Consult, Outside Slide No, (Bill Only) No
CUPPC Consult, w/USS Prof No, (Bill Only) No
CRHPC Consult, w/Comp Rvw of His No, (Bill Only) No
MANPC Morph Analysis, Nerve No, (Bill Only) No
LV4RP Level 4 Gross and Microscopic, RB No, (Bill Only) No
CSPPC Consult, w/Slide Prep No, (Bill Only) No
EM Electron Microscopy Yes No
IHPCI IHC Initial No, (Bill Only) No

Testing Algorithm

A battery of enzyme histochemical stains or immunostains are performed; other tests can be performed, as indicated, at an additional charge.

 

Wet tissue for consultation: When adequately prepared tissue is provided, routine testing will include PGP 9.5 (protein gene product 9.5) immunostain, morphometric analysis, Congo red stain, and hematoxylin and eosin stain. PGP 9.5 reactions cannot be done on previously embedded tissue, eg, paraffin blocks, epoxy blocks.

 

Slides and blocks sent for consultation must include PGP 9.5-reacted sections:

Special stains and studies performed on the case should be sent with the case for review. In order to determine an accurate diagnosis, some of these stains or studies may be deemed to warrant repeat testing, at an additional charge, at the discretion of the reviewing Mayo Clinic neuromuscular pathologist. In addition, testing requested by the referring physician (immunostains, molecular studies, etc) may not be performed if deemed unnecessary by the reviewing Mayo Clinic neuromuscular pathologist. For all consultations, ancillary testing necessary to determine a diagnosis is ordered at the discretion of the Mayo Clinic neuromuscular pathologist. An interpretation, which includes an evaluation of the specimen and determination of a diagnosis, will be provided within a formal pathology report.

 

For more information see Pathology Consultation Ordering Algorithm.

Method Name

Calculation of Epidermal Nerve Fiber Density

Reporting Name

Epidermal Nerve Fiber Density

Specimen Type

Varies

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred)
  Ambient 

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Small fiber peripheral neuropathy is a common neurological complaint and a frequent source of morbidity in many patient populations. Direct investigation of small fiber involvement has been limited as most classical techniques (eg, electromyography, nerve conduction studies, and nerve biopsy) focus on large diameter nerve fibers and may be normal in patients with small fiber neuropathies.

 

The advent of epidermal skin biopsies and PGP 9.5 (protein gene product 9.5) immunohistochemistry allows the direct visualization and morphologic assessment of small sensory fibers innervating the skin.(1) Assessment of intraepidermal nerve fiber density has been used to reliably demonstrate pathologic abnormalities in small fiber neuropathy of various etiologies including diabetes, HIV, systemic lupus erythematosus, and neurosarcoidosis. Further, the technique has been validated, shown to have acceptable sensitivity and specificity, and is minimally invasive. The publication of normative data for commonly tested sites such as the distal and proximal legs and arms permits direct comparison of patients to age- and sex-matched controls facilitating localization and diagnosis.(2-4)

 

Based on class 1 evidence and American Medical Association CPT code review process acceptance, intraepidermal nerve fiber density (IENFD) measurements are now an accepted investigational method in the workup of polyneuropathy, including the characterization and diagnosis of varieties of length-dependent small fiber polyneuropathies. IEFND measurements have been incorporated in recent practice guidelines published by the American Academy of Neurology and the European Federation of Neurological Science.(5,6)

Reference Values

An interpretive report will be provided.

Interpretation

The number of intraepidermally originating nerve fibers that cross the basement membrane between the dermis and epidermis are counted in several sections.(2,5) The total linear length of the epidermis is measured using standard morphometric techniques and a density of epidermal nerve fibers (number of fibers/mm) is reported. This value is compared to previously published normative data.

Cautions

Poor fixation, orientation, and improper handling of the tissue may hinder the neuromuscular pathologist's interpretation of the biopsy. For more information see Epidermal Nerve Fiber Density Preparation Instructions.

Supportive Data

Investigators at Mayo Clinic (Bolton, Winkelmann, Dyck) did previous work on cutaneous receptors preceding the recent work on intraepidermal nerve fiber densities. With recent findings, PJ Dyck and colleagues have developed the technique to national standards.(7)

Method Description

Immunohistochemical preparations are prepared using standard immunohistochemical techniques for PGP 9.5.(5) Using light microscopy, epidermal nerve fiber density is counted from PGP 9.5-reactive sections. Hematoxylin- and-eosin and Congo red stains are also reviewed.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Report Available

7 to 14 days: Cases requiring additional material or ancillary testing may require additional time.

Specimen Retention Time

Slides and blocks: Indefinitely

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

88305 (if appropriate)

88313 (if appropriate)

88321 (if appropriate)

88323 (if appropriate)

88323-26 (if appropriate)

88325 (if appropriate)

88348 (if appropriate)

88356 (if appropriate)

88342 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SPBX Epidermal Nerve Fiber Density In Process

 

Result ID Test Result Name Result LOINC Value
601780 Interpretation 59465-5
601791 Participated in the Interpretation No LOINC Needed
601792 Report electronically signed by 19139-5
601793 Addendum 35265-8
601794 Gross Description 22634-0
601795 Material Received 81178-6
601824 Case Number 80398-1
601913 Disclaimer 62364-5