Currentblue cross blue shield - tennesseePolicy N/A

Epidermal nerve fiber density (ENFD) testing (skin biopsy)

Defines coverage criteria and limitations for nerve fiber density testing from skin biopsy to diagnose small-fiber neuropathy for Blue Cross Blue Shield - Tennessee members.

Policy Summary

Payerblue cross blue shield - tennessee

PolicyEpidermal nerve fiber density (ENFD) testing (skin biopsy)

Policy CodePolicy N/A

Change TypeNo material change

Effective DateN/A

Next Review DateN/A

Key ActionObtain prior authorization documenting that all coverage criteria for diagnosing small-fiber neuropathy are met and include procedure codes when applicable.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

1Covered indication group

2Not-covered situations

6+Procedure codes referenced

MultipleReferences cited

~30Bibliography items

Coverage Criteria

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Diagnosis of small-fiber neuropathy (covered)

Covered when ALL of the following are met:

ENFD diagnostic coverage criteria: a) Individual presents with symptoms of painful sensory neuropathy; b) There is no history of a disorder known to predispose to painful neuropathy (e.g., diabetic neuropathy, toxic neuropathy, HIV neuropathy, celiac neuropathy, inherited neuropathy); c) Physical examination shows no evidence of findings consistent with large-fiber neuropathy (such as reduced or absent muscle-stretch reflexes or reduced proprioception and vibration sensation); d) Electromyography and nerve-conduction studies are normal and show no evidence of large-fiber neuropathy.all conditions required

Measurement of epidermal nerve fiber density (ENFD) from skin biopsy meets coverage only when all of the above conditions are satisfied.

Epidermal nerve fiber density (ENFD) measurement from skin biopsy is not covered when the request does not meet the specified diagnostic criteria for small‑fiber neuropathy. ENFD testing meets coverage only when all required conditions are present: symptoms of painful sensory neuropathy, no history of a disorder known to predispose to painful neuropathy, physical examination without findings of large‑fiber neuropathy, and normal electromyography and nerve‑conduction studies. For all other clinical situations, ENFD measurement does not meet coverage criteria.

A cited study reports that in patients with an alpha‑Galactosidase A variant, assessment of small nerve fibers cannot confirm a diagnosis of Fabry disease. This indicates that ENFD or small‑fiber assessment has limited diagnostic utility for confirming Fabry disease in that specific genetic context and should not be relied upon as definitive evidence of Fabry disease.

ENFD testing is considered not medically necessary for any situation other than the covered indication listed above for diagnosing small‑fiber neuropathy. Measurement of sweat gland nerve fiber density is also explicitly stated as not covered and therefore not medically necessary.

Coding and Billing

Procedure codes referencedCPT

88313	Special stain including interpretation and report; Group II, all other (eg, iron, trichrome), except stain for microorganisms, stains for enzyme constituents, or immunocytochemistry and immunohistochemistry.
88341	Immunohistochemistry or immunocytochemistry, per specimen; each additional single antibody stain procedure (List separately in addition to code for primary procedure).
88342	Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain procedure.
88344	Immunohistochemistry or immunocytochemistry, per specimen; each multiplex antibody stain procedure.
88346	Immunofluorescence, per specimen; initial single antibody stain procedure.
88350	Immunofluorescence, per specimen; each additional single antibody stain procedure (List separately in addition to code for primary procedure).
88356	Morphometric analysis; nerve

Provider Actions, Authorization, and Denials

Prior Authorization

Prior Authorization Not Specified

Prior authorization is not specified in this section of the policy. Providers should verify member-specific benefit coverage and any prior authorization requirements with Blue Cross Blue Shield of Tennessee before submitting requests.

Verify member benefits and prior authorization rules with the plan prior to service

Denial Risk

Denial Triggers for ENFD

Requests for epidermal nerve fiber density (ENFD) testing will be denied when the coverage criteria for diagnosing small-fiber (painful sensory) neuropathy are not met. Covered indication requires: presence of painful sensory neuropathy symptoms; no history of a disorder known to predispose to painful neuropathy; physical exam without signs of large-fiber neuropathy; and normal EMG/nerve conduction studies showing no large-fiber neuropathy.

Denial trigger: ENFD testing requested when one or more required diagnostic criteria (a–d) are not satisfied

Denial Risk

Sweat Gland Nerve Fiber Density Not Covered

Measurement of sweat gland nerve fiber density is not covered under this policy and will be denied.

Sweat gland nerve fiber density testing — Not covered / will be denied

Documentation Required

Required Clinical and Coding Documentation

Providers must document clinical findings and supporting diagnostic test results demonstrating that all coverage criteria for ENFD are met. Required documentation includes: clinical history showing painful sensory neuropathy symptoms; documentation of no history of disorders that predispose to painful neuropathy; physical examination findings absent for large-fiber neuropathy; and normal electromyography (EMG) and nerve conduction study (NCS) results.

Document symptomatic history of painful sensory neuropathy
Document absence of disorders known to predispose to painful neuropathy (e.g., diabetes, toxic exposures, HIV, celiac disease, inherited neuropathy)
Include physical exam notes confirming no large-fiber neuropathy signs (reflexes, proprioception/vibration)
Attach EMG and nerve conduction study reports showing no evidence of large-fiber neuropathy
Include applicable pathology/procedure coding (see CPT/HCPCS section)

Note

No Procedural Documentation Specified

This section contains no procedural step-by-step documentation requirements or specific provider actions for performing the biopsy or laboratory processing. Refer to clinical practice resources and the referenced CPT/HCPCS codes for procedural coding and laboratory billing guidance.

No procedural technique or specimen-handling instructions provided in policy — follow local laboratory and clinical practice guidance
Use listed CPT/HCPCS codes for billing and consult payer for any additional submission requirements

Step Therapy

No Step Therapy Requirements

No step therapy requirements are described in this section of the policy.

There are no step therapy or prior-treatment sequencing requirements stated for ENFD or related testing in this section

Definitions

inv-16: Epidermal nerve fiber density (ENFD) — definition and measurement description

TermEpidermal nerve fiber density (ENFD)

DefinitionNumber and morphology of axons within the epidermis measured from a skin biopsy stained for PGP 9.5 to assess small‑fiber neuropathy.

Measurement methodSkin punch biopsy with immunohistochemical staining for PGP 9.5; quantification of intraepidermal axon count per length of epidermis and assessment of axon morphology.

Clinical useUsed to determine presence and degree of small‑fiber neuropathy when clinical symptoms suggest painful sensory neuropathy and other testing does not indicate large‑fiber involvement.

Reference descriptionENFD is determined by evaluating the number and morphology of axons within the epidermis on PGP 9.5‑stained skin biopsy specimens (McCarthy et al., 1995).

inv-17: PGP 9.5 — neuronal marker used in skin biopsy immunohistochemistry

MarkerPGP 9.5 (protein gene product 9.5)

Biologic roleNeuron‑specific protein that avidly stains axons, used as an immunohistochemical marker for nerve fibers in skin biopsy.

Use in testingApplied to skin biopsy specimens to visualize intraepidermal nerve fibers for ENFD quantification and morphological assessment.

Foundational referenceWilkinson et al. (1989) identified PGP 9.5 as a neuron‑specific protein (ubiquitin carboxyl‑terminal hydrolase) used for axonal staining.

OpenPayer

Epidermal nerve fiber density (ENFD) testing (skin biopsy)

Coverage Criteria

Coding and Billing

Provider Actions, Authorization, and Denials

Background

Definitions