L04.3 ICD-10-CM Code: Acute lymphadenitis of lower limb

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for L04.3 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 L04.3 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for L04.3

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

Before you code L04.3

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with L04.3. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in L04.3’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewI88.1, R59, B20, I88.9, I88.0

Consider L04.3. 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).

Acuity

Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

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

• Excludes1 — check before selecting L04.3(5 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with L04.3: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareI88.1, R59, B20, I88.9, I88.0

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

• Excludes2 — not part of L04.3(14 notes)

  Coding workflow: The conditions named in this note are not included in L04.3. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareL04.1, 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 L04.3(1 note)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with L04.3 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 (2)

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.

• Lymphadenitis, acute, hip
• Lymphadenitis, acute, limb, lower

Don’t confuse L04.3 with…

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

The codes most likely to be picked instead of L04.3 — 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.

• I88.1— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of chronic or subacute lymphadenitis, except mesenteric moves the case to I88.1; the two are not reported together unless documented as unrelated.

  Full comparison: L04.3 vs I88.1 →

• R59— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of enlarged lymph nodes moves the case to R59; the two are not reported together unless documented as unrelated.

  Full comparison: L04.3 vs R59 →

• B20— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of human immunodeficiency virus [HIV] disease resulting in generalized lymphadenopathy moves the case to B20; the two are not reported together unless documented as unrelated.

  Full comparison: L04.3 vs B20 →

• I88.9— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of lymphadenitis NOS moves the case to I88.9; the two are not reported together unless documented as unrelated.

  Full comparison: L04.3 vs I88.9 →

• I88.0— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of nonspecific mesenteric lymphadenitis moves the case to I88.0; the two are not reported together unless documented as unrelated.

  Full comparison: L04.3 vs I88.0 →

• L04.9— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Acute lymphadenitis, unspecified” takes L04.9; specificity in the record moves it back here.

  Full comparison: L04.3 vs L04.9 →

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.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
2. 5 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
3. 14 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

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 L04.3 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 across 2 chapters: I88 — Nonspecific lymphadenitis (via L04.-), R59 — Enlarged lymph nodes (via L04.-).

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: D75 — Other and unspecified diseases of blood and blood-forming organs (via L04.-), L89 — Pressure ulcer (via L04.-), L97 — Non-pressure chronic ulcer of lower limb, not elsewhere classified (via L04.-), L98.4 — Non-pressure chronic ulcer of skin, not elsewhere classified (via L04.-), L98.A — Non-pressure chronic ulcer of upper limb, not elsewhere classified (via L04.-).

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 5 MS-DRGs: DRG 791 (MDC 15), DRG 793 (MDC 15), DRG 814 (MDC 16), DRG 815 (MDC 16), DRG 816 (MDC 16).

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).

L03.32A — Acute lymphangitis of flank, 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, L04.0 — Acute lymphadenitis of face, head and neck, L04.1 — Acute lymphadenitis of trunk, L04.2 — Acute lymphadenitis of upper 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, L05.91 — Pilonidal cyst without abscess, L05.92 — Pilonidal sinus without abscess, L08.0 — Pyoderma, L08.1 — Erythrasma, L08.81 — Pyoderma vegetans, L08.82 — Omphalitis not of newborn, +150 more

Same Index main term, other category

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

A01.09 — Typhoid fever with other complications (mesenteric, due to Salmonella typhi), A18.39 — Retroperitoneal tuberculosis (mesenteric, tuberculous), A31.8 — Other mycobacterial infections (mycobacterial), A36.89 — Other diphtheritic complications (due to, diphtheria), A51.49 — Other secondary syphilitic conditions (syphilitic), A52.79 — Other symptomatic late syphilis (syphilitic, late), A54.89 — Other gonococcal infections (gonorrheal), A55 — Chlamydial lymphogranuloma (venereum) (venereal), A57 — Chancroid (chancroidal), B74.0 — Filariasis due to Wuchereria bancrofti (due to, Wuchereria bancrofti), B74.1 — Filariasis due to Brugia malayi (due to, Brugia), B74.2 — Filariasis due to Brugia timori (due to, Brugia, timori), I88.0 — Nonspecific mesenteric lymphadenitis (mesenteric), I88.1 — Chronic lymphadenitis, except mesenteric (chronic), I88.8 — Other nonspecific lymphadenitis (regional, nonbacterial), I88.9 — Nonspecific lymphadenitis, unspecified, J60 — Coalworker's pneumoconiosis (anthracosis), O08.0 — Genital tract and pelvic infection following ectopic and molar pregnancy (with ectopic or molar pregnancy), O91.22 — Nonpurulent mastitis associated with the puerperium (breast, puerperal, postpartum)

Contextual Map

Every relationship of L04.3 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 L04.3 with these 8 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
• L00-L08 — Infections of the skin and subcutaneous tissue[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes2

• L04.1 — Acute lymphadenitis of trunk[Excludes2]: “acute lymphadenitis of groin (L04.1)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

• I88 — Nonspecific lymphadenitis[Excludes1](via L04.-): “acute lymphadenitis, except mesenteric (L04.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• R59 — Enlarged lymph nodes[Excludes1](via L04.-): “acute lymphadenitis (L04.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

• D75 — Other and unspecified diseases of blood and blood-forming organs[Excludes2](via L04.-): “acute lymphadenitis (L04.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• L89 — Pressure ulcer[Excludes2](via L04.-): “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 L04.-): “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 L04.-): “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 L04.-): “skin infections (L00-L08)”— 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

• 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
• DRG 814 — RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITH MCC[MS-DRG]: “RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITH MCC (MDC 16)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 815 — RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITH CC[MS-DRG]: “RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITH CC (MDC 16)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 816 — RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITHOUT CC/MCC[MS-DRG]: “RETICULOENDOTHELIAL AND IMMUNITY DISORDERS WITHOUT CC/MCC (MDC 16)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• 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
• MDC 16 — Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders[MDC crossing]: “Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders — 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. 1,614 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Lymphadenitis, acute, hip[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Lymphadenitis, acute, limb, lower[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• L04 — Acute lymphadenitis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L04.0 — Acute lymphadenitis of face, head and neck[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L04.1 — Acute lymphadenitis of trunk[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L04.2 — Acute lymphadenitis of upper limb[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L04.8 — Acute lymphadenitis of other sites[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• L04.9 — Acute lymphadenitis, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

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 L04.3 in its code family, with their registry titles.

• L04 — Acute lymphadenitis
• L04.0 — Acute lymphadenitis of face, head and neck
• L04.1 — Acute lymphadenitis of trunk
• L04.2 — Acute lymphadenitis of upper limb
• L04.8 — Acute lymphadenitis of other sites
• L04.9 — Acute lymphadenitis, unspecified

View all codes in the L04 family