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L05.91 ICD-10-CM Code: Pilonidal cyst without abscess

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
3 inclusion terms · 15 Excludes2 · 1 use-additional code

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for L05.91 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on L05.91 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Pilonidal dimple
  • Postanal dimple
  • Pilonidal cyst NOS

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code (B95-B97) to identify infectious agent.

Source: inherited from L00-L08

Coder workflow for L05.91

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Excludes2 — not part of L05.91(15 notes)

    Coding workflow: The conditions named in this note are not included in L05.91. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareQ82.6, H00.0, L30.3, L93.2, M79.3, M54.0

    See the official tabular notes · Guidelines I.A.12.b

  • Use Additional Code — after identifying L05.91(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with L05.91 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with L05.91?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Pilonidal cyst without abscess is a billable ICD-10-CM diagnosis code (L05.91).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name L05.91 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Excludes1 notes: Q43.6 — Congenital fistula of rectum and anus (via L05.-), Q82 — Other congenital malformations of skin (via L05.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 5 Excludes2 notes across 2 chapters: L89 — Pressure ulcer (via L05.-), L97 — Non-pressure chronic ulcer of lower limb, not elsewhere classified (via L05.-), L98.4 — Non-pressure chronic ulcer of skin, not elsewhere classified (via L05.-), L98.A — Non-pressure chronic ulcer of upper limb, not elsewhere classified (via L05.-), Q82.6 — Congenital sacral dimple.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 602 (MDC 09), DRG 603 (MDC 09).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):SKN001 — Skin and subcutaneous tissue infections (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Skin and subcutaneous tissue infections).

L03.891 — Acute lymphangitis of head [any part, except face], L03.898 — Acute lymphangitis of other sites, L03.90 — Cellulitis, unspecified, L03.91 — Acute lymphangitis, unspecified, L04.0 — Acute lymphadenitis of face, head and neck, L04.1 — Acute lymphadenitis of trunk, L04.2 — Acute lymphadenitis of upper limb, L04.3 — Acute lymphadenitis of lower limb, L04.8 — Acute lymphadenitis of other sites, L04.9 — Acute lymphadenitis, unspecified, L05.01 — Pilonidal cyst with abscess, L05.02 — Pilonidal sinus with abscess, L05.92 — Pilonidal sinus without abscess, L08.0 — Pyoderma, L08.1 — Erythrasma, L08.81 — Pyoderma vegetans, L08.82 — Omphalitis not of newborn, L08.89 — Other specified local infections of the skin and subcutaneous tissue, L08.9 — Local infection of the skin and subcutaneous tissue, unspecified, L30.3 — Infective dermatitis, +150 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Cyst”; these codes share that main term but sit in a different category of the Tabular List.

K38.8 — Other specified diseases of appendix (appendix), K62.89 — Other specified diseases of anus and rectum (anus), K63.89 — Other specified diseases of intestine (colon), K66.8 — Other specified disorders of peritoneum (omentum), K68.9 — Other disorders of retroperitoneum (retroperitoneal), K76.89 — Other specified diseases of liver (liver), K82.8 — Other specified diseases of gallbladder (gallbladder), K83.5 — Biliary cyst (bile duct), K86.2 — Cyst of pancreas (pancreas, pancreatic), K86.3 — Pseudocyst of pancreas (pancreas, pancreatic, false), L72.0 — Epidermal cyst (inclusion), L72.11 — Pilar cyst (pilar), L72.12 — Trichodermal cyst (trichodermal), L72.3 — Sebaceous cyst (sebaceous), L72.8 — Other follicular cysts of the skin and subcutaneous tissue (follicular, skin, specified NEC), L72.9 — Follicular cyst of the skin and subcutaneous tissue, unspecified (skin), L74.8 — Other eccrine sweat disorders (sweat gland or duct), M24.85 — Other specific joint derangements of hip, not elsewhere classified (paralabral, hip), M27.0 — Developmental disorders of jaws (Stafne's), M27.40 — Unspecified cyst of jaw (jaw), +196 more

Contextual Map

Every relationship of L05.91 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run L05.91 with these 7 related codes in Claim Check

Hierarchy

Excludes2

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 09 — Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast[MDC crossing]: “Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 7,376 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Cyst (colloid) (mucous) (simple) (retention), pilonidal (infected) (rectum)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "L05.91 — Pilonidal cyst without abscess." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/l05.91-pilonidal-cyst-without-abscess

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Pilonidal cyst without abscess

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to L05.91 in its code family, with their registry titles.

View all codes in the L05 family