2026 ICD-10-CM Diagnosis Code L66.3Perifolliculitis capitis abscedens

ICD-10-CM Codes›L00–L99›L60-L75›L66

ICD-10-CM L66.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

L66.3 is a billable ICD-10-CM diagnosis code for perifolliculitis capitis abscedens. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. Coders also document this condition as follicular occlusion tetrad - hidradenitis, acne conglobata, dissecting cellulitis, pilonidal sinus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified skin disorders.

Code Identity

ICD-10-CM Code
L66.3
Billable Status
Yes — Valid for Submission
Code Describes
Perifolliculitis capitis abscedens
Short Description
Perifolliculitis capitis abscedens
Same as the full description in the CMS dataset.
Parent Code
L66
Cicatricial alopecia [scarring hair loss]

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL60-L75Disorders of skin appendages
CategoryL66Cicatricial alopecia [scarring hair loss]
This CodeL66.3Perifolliculitis capitis abscedens

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Follicular occlusion tetrad - hidradenitis, acne conglobata, dissecting cellulitis, pilonidal sinus
  • Follicular occlusion triad - hidradenitis, acne conglobata, dissecting cellulitis of scalp
  • Perifolliculitis
  • Perifolliculitis capitis abscedens
  • Perifolliculitis capitis abscedens et suffodiens
  • Scalp folliculitis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Folliculitis(superficial)
      • abscedens et suffodiens
    • Perifolliculitis
      • abscedens, caput, scalp
    • Perifolliculitis
      • capitis, abscedens (et suffodiens)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SKN007
Other specified and unspecified skin disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Hidradenitis Suppurativa

    a chronic, suppurative inflammation of the apocrine sweat glands, that is characterized by clusters of bumps or sores.

Patient EducationClinical

Hair Loss

You lose up to 100 hairs from your scalp every day. That's normal, and in most people, those hairs grow back. But many men -- and some women -- lose hair as they grow older. You can also lose your hair if you have certain diseases, such as thyroid problems, diabetes, or lupus.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert L66.3 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
704.8 Hair diseases NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About L66.3Overview

Is L66.3 (Cicatricial alopecia [scarring hair loss]) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report perifolliculitis capitis abscedens on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does L66.3 group to?

When perifolliculitis capitis abscedens is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of L66.3?

Under the General Equivalence Mappings, perifolliculitis capitis abscedens converts to ICD-9-CM 704.8 (hair diseases NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.