L02.91 ICD-10-CM Code: Cutaneous abscess, unspecified

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for L02.91 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 L02.91 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for L02.91

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

Before you code L02.91

1. Unspecified does not mean incorrect. When the record gives no greater specificity, L02.91 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

1. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — L02.91 is appropriate when the documentation goes no further.

Consider L02.91. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

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 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.

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes2 — not part of L02.91(16 notes)

  Coding workflow: The conditions named in this note are not included in L02.91. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareK61, N76.4, N48.2, N49, H00.0, L30.3

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

• Use Additional Code — after identifying L02.91(2 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with L02.91 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

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.

Indexed Clinical Terms (3)

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.

• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), phagedenic NOS
• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), rupture NOS (spontaneous)

Don’t confuse L02.91 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of L02.91 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• K61— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of abscess of anus and rectal regions adds K61; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs K61 →

• N76.4— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of abscess of female genital organs (external) adds N76.4; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs N76.4 →

• N48.2— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of abscess of male genital organs (external) adds N48.2; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs N48.2 →

• N49— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of abscess of male genital organs (external) adds N49; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs N49 →

• H00.0— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of hordeolum adds H00.0; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs H00.0 →

• L30.3— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of infective dermatitis adds L30.3; it is not part of this code and both may be reported when both are documented.

  Full comparison: L02.91 vs L30.3 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

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 L02.91 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 4 Excludes2 notes: L89 — Pressure ulcer (via L02.-), L97 — Non-pressure chronic ulcer of lower limb, not elsewhere classified (via L02.-), L98.4 — Non-pressure chronic ulcer of skin, not elsewhere classified (via L02.-), L98.A — Non-pressure chronic ulcer of upper limb, not elsewhere classified (via L02.-).

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

Referenced by 1 Use Additional Code instruction: T65.84 — Toxic effect of xylazine (via L02.-).

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 43 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 7 MS-DRGs: DRG 573 (MDC 09), DRG 574 (MDC 09), DRG 575 (MDC 09), DRG 602 (MDC 09), DRG 603 (MDC 09), DRG 791 (MDC 15), DRG 793 (MDC 15).

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 process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A49.02 — Methicillin resistant Staphylococcus aureus infection, unspecified site, A49.1 — Streptococcal infection, unspecified site, A49.2 — Hemophilus influenzae infection, unspecified site, A49.3 — Mycoplasma infection, unspecified site, A49.8 — Other bacterial infections of unspecified site, A49.9 — Bacterial infection, unspecified, B78.1 — Cutaneous strongyloidiasis, E83.2 — Disorders of zinc metabolism, L02.811 — Cutaneous abscess of head [any part, except face], L02.818 — Cutaneous abscess of other sites, L03.811 — Cellulitis of head [any part, except face], L03.818 — Cellulitis of other sites, 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, L08.0 — Pyoderma, L08.81 — Pyoderma vegetans, L08.82 — Omphalitis not of newborn, L08.89 — Other specified local infections of the skin and subcutaneous tissue, +22 more

Same clinical category (CCSR)

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

L02.629 — Furuncle of unspecified foot, L02.631 — Carbuncle of right foot, L02.632 — Carbuncle of left foot, L02.639 — Carbuncle of unspecified foot, L02.811 — Cutaneous abscess of head [any part, except face], L02.818 — Cutaneous abscess of other sites, L02.821 — Furuncle of head [any part, except face], L02.828 — Furuncle of other sites, L02.831 — Carbuncle of head [any part, except face], L02.838 — Carbuncle of other sites, L02.92 — Furuncle, unspecified, L02.93 — Carbuncle, unspecified, L03.011 — Cellulitis of right finger, L03.012 — Cellulitis of left finger, L03.019 — Cellulitis of unspecified finger, L03.021 — Acute lymphangitis of right finger, L03.022 — Acute lymphangitis of left finger, L03.029 — Acute lymphangitis of unspecified finger, L03.031 — Cellulitis of right toe, L03.032 — Cellulitis of left toe, +150 more

Same Index main term, other category

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

K65.1 — Peritoneal abscess (omentum), K68.11 — Postprocedural retroperitoneal abscess (postoperative, retroperitoneal), K68.12 — Psoas muscle abscess (psoas muscle), K68.19 — Other retroperitoneal abscess (presacral), K6A.01 — Prevesical abscess (prevesical), K6A.09 — Other pelvic abscess (pelvis, pelvic), K75.0 — Abscess of liver (liver), K81.0 — Acute cholecystitis (gallbladder), K94.02 — Colostomy infection (colostomy), K94.12 — Enterostomy infection (ileostomy), L04.0 — Acute lymphadenitis of face, head and neck (neck, lymph gland or node), L04.1 — Acute lymphadenitis of trunk (inguinal, lymph gland or node), L04.2 — Acute lymphadenitis of upper limb (axilla, lymph gland or node), L05.01 — Pilonidal cyst with abscess (pilonidal), L74.8 — Other eccrine sweat disorders (sweat gland), L75.8 — Other apocrine sweat disorders (sudoriparous), M00.9 — Pyogenic arthritis, unspecified (knee, joint), M27.2 — Inflammatory conditions of jaws (jaw), M46.28 — Osteomyelitis of vertebra, sacral and sacrococcygeal region (sacrum, nontuberculous), M65.00 — Abscess of tendon sheath, unspecified site (tendon), +143 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test

Contextual Map

Every relationship of L02.91 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 L02.91 with these 5 related codes in Claim Check

Hierarchy

• L00-L99 — Chapter 12: Diseases of the Skin and Subcutaneous Tissue (L00-L99) (L00-L99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes2 notes

• L89 — Pressure ulcer[Excludes2](via L02.-): “skin infections (L00-L08)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• L97 — Non-pressure chronic ulcer of lower limb, not elsewhere classified[Excludes2](via L02.-): “skin infections (L00-L08)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• L98.4 — Non-pressure chronic ulcer of skin, not elsewhere classified[Excludes2](via L02.-): “skin infections (L00-L08)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• L98.A — Non-pressure chronic ulcer of upper limb, not elsewhere classified[Excludes2](via L02.-): “skin infections (L00-L08)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Use Additional Code instructions

• T65.84 — Toxic effect of xylazine[Use Additional Code](via L02.-): “cutaneous abscess, furuncle and carbuncle (L02.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• SKN001 — Skin and subcutaneous tissue infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 573 — SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITH MCC[MS-DRG]: “SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITH MCC (MDC 09)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 574 — SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITH CC[MS-DRG]: “SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITH CC (MDC 09)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 575 — SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITHOUT CC/MCC[MS-DRG]: “SKIN GRAFT FOR SKIN ULCER OR CELLULITIS WITHOUT CC/MCC (MDC 09)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 602 — CELLULITIS WITH MCC[MS-DRG]: “CELLULITIS WITH MCC (MDC 09)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 603 — CELLULITIS WITHOUT MCC[MS-DRG]: “CELLULITIS WITHOUT MCC (MDC 09)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

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
• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — 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.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), phagedenic NOS[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), rupture NOS (spontaneous)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (40)

• L02 — Cutaneous abscess, furuncle and carbuncle[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.439 — Carbuncle of limb, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.5 — Cutaneous abscess, furuncle and carbuncle of hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.51 — Cutaneous abscess of hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.511 — Cutaneous abscess of right hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.512 — Cutaneous abscess of left hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.519 — Cutaneous abscess of unspecified hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L02.52 — Furuncle hand[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to L02.91 in its code family, with their registry titles.

• L02.811 — Cutaneous abscess of head [any part, except face]
• L02.818 — Cutaneous abscess of other sites
• L02.82 — Furuncle of other sites
• L02.821 — Furuncle of head [any part, except face]
• L02.828 — Furuncle of other sites
• L02.83 — Carbuncle of other sites
• L02.831 — Carbuncle of head [any part, except face]
• L02.838 — Carbuncle of other sites
• L02.9 — Cutaneous abscess, furuncle and carbuncle, unspecified
• L02.92 — Furuncle, unspecified

View all codes in the L02 family