Skin Ulcers (Non-Pressure, Non-Venous) — Clinical Documentation Guide (2026)

This Clinical Documentation Guide (CDG) covers non-pressure, non-venous chronic skin ulcers — primarily the FY2026 ICD-10-CM categories L97 (non-pressure chronic ulcer of lower limb, not elsewhere classified) and L98.4 (non-pressure chronic ulcer of skin, not elsewhere classified). Pressure ulcers (L89) and venous stasis ulcers (I87.2, I83.0–I83.2) are distinct conditions with their own CDGs — this guide links to both where appropriate. Content is intended for AAPC/AHIMA-credentialed coders, CDI specialists, and auditors working in wound care, vascular surgery, podiatry, and complex medical-surgical settings.

🔍 1. Definition

A non-pressure, non-venous chronic skin ulcer is a full-thickness skin defect of at least 4–6 weeks’ duration that does not result primarily from sustained pressure over a bony prominence and is not caused primarily by venous hypertension or venous insufficiency. These ulcers arise instead from arterial insufficiency, neuropathy (especially diabetic), vasculitis, inflammatory dermatoses (pyoderma gangrenosum, calciphylaxis), trauma, malignancy, or a combination of etiologies, as classified by the CDC/NCHS ICD-10-CM classification.

The ICD-10-CM categories L97 and L98.4 are residual “not elsewhere classified” (NEC) categories, meaning they apply only when the ulcer cannot be more specifically assigned to a condition-specific code (e.g., diabetic foot ulcer combination code E11.621 + L97.5xx, or arterial ulcer from atherosclerosis I70.2xx–I70.7xx). Documentation of etiology is therefore critical to accurate code assignment, as detailed in the FY2026 ICD-10-CM Official Coding Guidelines.

Depth (severity) is the single most important documentation element for these codes — the 6th character determines whether HCC v28 RAF credit is generated, and the difference between a shallow ulcer (skin breakdown only) and one exposing fat, muscle, or bone can change risk-adjusted reimbursement by hundreds of dollars per member per year.

🗂️ 2. Alternative Terminology

🩺 3. Signs & Symptoms

Clinical presentation varies significantly by etiology but shared features include:

• Location: Lower extremity (thigh, calf, ankle, heel, dorsum of foot) for L97; trunk, back, buttock, and non-lower-extremity sites for L98.4
• Ulcer bed: May be pale/sloughy (arterial/ischemic), pink/granulating (healing), yellow/necrotic (infected or avascular), or black/eschar (dry necrosis)
• Wound edges: Punched-out (arterial), irregular/undermined (neuropathic), violaceous/irregular (pyoderma gangrenosum), or stellate (vasculitic)
• Pain: Often severe and worsening at night in arterial ulcers; notably absent in neuropathic ulcers; moderate in venous (distinguish from L97/L98.4 scope)
• Surrounding skin: Pallor, dependent rubor, hair loss, and shiny atrophic skin (arterial); hyperpigmentation (post-inflammatory); normal to indurated (neuropathic)
• Palpable pulses: Diminished or absent dorsalis pedis / posterior tibial pulses (arterial)
• Associated symptoms: Claudication, rest pain, sensory neuropathy, autonomic neuropathy signs (anhidrosis, warm foot in Charcot)
• Signs of infection: Erythema, warmth, purulent discharge, malodor, crepitus (gas-forming organisms), fever, leukocytosis
• Depth indicators documented by clinicians: “Skin breakdown only,” “fat visible,” “tendon/muscle exposed,” “bone visible” or “probing to bone positive” — each maps to a different 6th-character depth code

🧭 4. Differential Diagnosis

📋 5. Clinical Indicators for Coders / CDI

🦴 6. Anatomy & Pathophysiology

Relevant Anatomy

The skin is a layered organ comprising the epidermis (outermost; keratinized stratified squamous epithelium), the dermis (collagen/elastin matrix, hair follicles, sweat glands, sensory nerves, blood vessels), and the hypodermis/subcutaneous fat layer (adipose connective tissue serving as insulation and vascular conduit). Below the skin lie fascia, muscle, tendon, and bone. The 6th-character depth codes in L97 and L98.4 directly map to these anatomic layers, as described in the NCBI anatomy reference (StatPearls — Integumentary System):

• 6th char 1 — Skin breakdown only: Ulcer limited to epidermis ± superficial dermis
• 6th char 2 — Fat layer exposed: Full-thickness dermis destroyed; subcutaneous fat visible
• 6th char 3 — Necrosis of muscle: Full-thickness wound with muscle necrosis (myonecrosis)
• 6th char 4 — Necrosis of bone: Bone exposed and/or necrotic (osteonecrosis); consider M86 osteomyelitis
• 6th char 5 — Muscle involvement without necrosis: Muscle exposed but viable; tendon visible
• 6th char 6 — Bone involvement without necrosis: Bone visible/probed but not necrotic; high infection risk
• 6th char 8 — Other specified severity
• 6th char 9 — Severity unspecified (documentation inadequate)

Pathophysiology by Etiology

Arterial/Ischemic: Peripheral arterial occlusive disease (PAOD) reduces tissue oxygen delivery. ABI <0.4 indicates critical limb ischemia. Tissue hypoxia causes coagulative necrosis; wounds fail to granulate. Per AHA/ACC 2024 Peripheral Artery Disease Guidelines, critical limb-threatening ischemia (CLTI) is defined by rest pain, gangrene, or ischemic wounds.

Diabetic Neuropathic: Sensory neuropathy eliminates protective pain sensation; motor neuropathy causes foot deformity (claw toes, Charcot); autonomic neuropathy produces dry skin and fissures. Repetitive mechanical trauma on insensate skin creates plantar ulcers at pressure points. Hyperglycemia impairs neutrophil chemotaxis, collagen synthesis, and angiogenesis. The ADA Standards of Care 2024 classify diabetic foot ulcers using the Wagner or PEDIS systems and emphasize the combination E11.621 + L97.5xx as the mandatory coding pair.

Inflammatory/Vasculitic: Immune-complex deposition or neutrophilic infiltration (pyoderma gangrenosum — L88) causes tissue destruction. Calciphylaxis involves medial calcification and thrombosis of dermal arterioles in CKD stage 4–5/dialysis patients, producing ischemic necrosis. Per StatPearls — Calciphylaxis, mortality is 45–80% at 1 year.

Wound Healing Biology: Normal healing progresses through hemostasis (0–2 days) → inflammation (1–4 days) → proliferation (4–21 days) → remodeling (21 days–2 years). Chronic non-healing wounds are arrested in a persistent pro-inflammatory state with elevated matrix metalloproteinases (MMPs), reduced growth factors, and senescent cells, as reviewed in PMC Wound Repair Review (2022).

💊 7. Medication Impact / Treatment

Pharmacologic management is etiology-dependent and directly affects code assignment and clinical indicators:

Antiplatelet / Anticoagulant Agents

Aspirin, clopidogrel (Plavix), ticagrelor, rivaroxaban, and warfarin are used in arterial ulcer patients. Presence of anticoagulation may be relevant to bleeding risk documentation for wound procedures. Use Z79.01 (anticoagulant) or Z79.02 (antiplatelet) as secondary codes per FY2026 Guidelines Section I.C.21.c.3.

Insulin / Antidiabetic Agents

In diabetic foot ulcer patients, insulin use (Z79.4) or oral antidiabetic agents (Z79.84) must be coded when applicable. Long-term insulin use is a secondary code only — it does not change E11 to E10 (Type 1 DM).

Wound-Directed Pharmacology

• Topical antimicrobials: Silver sulfadiazine, cadexomer iodine, PHMB — used for infected/critically colonized wounds
• Becaplermin gel (Regranex, PDGF-BB): FDA-approved for diabetic neuropathic lower-extremity ulcers; limited to one tube/course; requires REMS acknowledgment
• Collagenase (Santyl): Enzymatic debridement agent coded under 97602 (non-selective debridement) when applied by a clinician
• Pentoxifylline: Used off-label for arterial insufficiency and venous ulcers; improves RBC deformability
• Cilostazol: PDE-3 inhibitor approved for claudication in PAD; may improve peripheral perfusion around arterial ulcers
• Systemic antibiotics: For confirmed wound infection; organism-specific; document causative organism for ICD-10-CM B95–B97 codes
• Immunosuppressants (PG, vasculitis): Prednisone, cyclosporine, infliximab; relevant for pathergy-based ulcer management; document underlying condition for accurate L88 vs. L97 assignment

Preview ends here. The full guide continues with FY2026 ICD-10-CM code sets, CPT surgical coding, MS-DRG mapping, reimbursement guidance, CDI query templates, and an audit checklist — all available to CCO Members.

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📘 8. ICD-10-CM Guidelines (FY2026)

The following guidelines from the FY2026 ICD-10-CM Official Coding Guidelines govern L97 and L98.4 assignment:

Etiology / Manifestation Convention (Section I.A.6)

When a skin ulcer is a manifestation of an underlying disease, the underlying condition is sequenced first. The ICD-10-CM Index provides “use additional code” notes at the underlying condition to point to L97/L98.4 as manifestation codes. Examples:

• Atherosclerosis with ulceration: I70.2xx–I70.7xx sequenced first; L97.xxx added for anatomic site detail
• Diabetic foot ulcer: E11.621 sequenced first (or as principal inpatient diagnosis when DM is the reason for admission); L97.5xx added
• Vasculitis with ulcer: M05.xx, M32.xx, M31.xx sequenced first; L97/L98.4 added

Non-Pressure Ulcer Coding (Section I.C.12.a.4–6)

• I.C.12.a.4 — Code First: Assign a code from L97 or L98.4 first if the ulcer is the reason for the encounter AND no documented causal condition exists; then code the associated conditions
• I.C.12.a.5 — Depth Assignment: When the depth is not documented, assign the 6th character “9” (unspecified). Do NOT assign a higher-severity depth without clinician documentation. Query the provider rather than defaulting to “9.”
• I.C.12.a.6 — Multiple Ulcers: Each anatomically distinct ulcer is coded separately. A patient with right calf and left ankle ulcers requires two codes: one from L97.2xx and one from L97.3xx with appropriate laterality and depth characters
• I.C.12.a.7 — Progress Documentation: The stage/depth of a non-pressure ulcer at the time of coding is defined by the most current clinical assessment; if the wound is improving and depth decreases, code the current documented depth

Combination Codes for Diabetic Foot Ulcers

Per FY2026 Guidelines Section I.C.4.a, when diabetes mellitus is associated with a foot ulcer, the combination code E11.621 (or E10.621, E13.621) captures both conditions. Add L97.5xx to identify the specific foot site, laterality, and depth. Never assign L97.5xx alone for a diabetic patient without the E11.621 combination code — doing so misrepresents etiology and forfeits HCC 37 RAF credit.

Atherosclerosis with Ulceration

Per coding guidelines for I70 (atherosclerosis), when atherosclerotic peripheral arterial disease is the documented cause of a lower limb ulcer, assign the appropriate combination code from I70.2xx–I70.7xx (which includes the ulcer) rather than L97.xxx as the primary code. Add L97.xxx for anatomic detail. Gangrene (I96) is coded additionally if present.

Pressure Ulcer vs. Non-Pressure Ulcer Distinction

If documentation is ambiguous, query the provider. Do not assign L89 (pressure ulcer) without clear provider documentation of pressure etiology. Per AHA Coding Clinic 4Q 2016, the distinction between pressure and non-pressure ulcer requires clinician judgment and must be supported by clinical documentation.

🔢 9. ICD-10-CM Code Set (FY2026)

L97 — Non-Pressure Chronic Ulcer of Lower Limb, NEC

Code structure: L97 . [site] [laterality] [depth]

4th character = site | 5th character = laterality (1=right, 2=left, 9=unspecified) | 6th character = depth/severity

L98.4 — Non-Pressure Chronic Ulcer of Skin, NEC (Non-Lower-Limb Sites)

Associated / Additional Codes Frequently Used

🔎 10. Indexing

Locate codes via the FY2026 ICD-10-CM Index to Diseases and Injuries:

🏥 11. CPT (2026)

CPT codes for wound care are from the AMA CPT 2026 codebook and are used in outpatient, ambulatory, and hospital-based wound care settings.

🧾 12. HCPCS (2026)

📚 13. AHA Coding Clinic (Recent Guidance)

💰 14. HCC / Risk Adjustment (v28)

CMS-HCC Model Version 28 (effective for CY2024+ risk-adjusted payments, as detailed in the CMS MA risk adjustment documentation) provides the following RAF credit for non-pressure chronic ulcer diagnoses:

✍️ 15. CDI Query Templates

All queries below are written in compliance with AHIMA 2019 Physician Query Practice Brief and ACDIS Guidelines for Practice: non-leading, clinically consistent, multiple-choice format.

🧑‍⚕️ 16. Treatments (Clinical)

Evidence-Based Wound Care Framework

Treatment is guided by the TIME framework (Tissue, Infection/Inflammation, Moisture, Edge/Epithelialization) and etiology-specific interventions:

Local Wound Care

• Debridement: Removal of devitalized tissue is foundational. Options: sharp/surgical (11042–11044), enzymatic (collagenase/Santyl — 97602), autolytic (hydrogel dressings), mechanical (wet-to-dry — 97602), or biological (maggot therapy). Method chosen based on wound status, patient tolerance, and depth
• Dressing selection: Match dressing to wound characteristics — hydrogel/alginate for dry/minimal exudate; foam/alginate for moderate-to-heavy exudate; antimicrobial silver/cadexomer iodine for biofilm/critically colonized wounds
• Negative Pressure Wound Therapy (NPWT): VAC/NPWT (97610, A6550) for complex, high-exudate, or post-surgical wounds; promotes granulation by macrodeformation and fluid removal
• Compression: Unna boot (29581) used for mixed arterial-venous ulcers when ABI ≥0.6; contraindicated in ABI <0.5 (pure arterial)

Skin Substitutes and Grafts

Advanced cellular and acellular matrices (Apligraf, Epifix, GraftJacket, Epicord) are applied when standard of care wound management fails after 4–8 weeks. The FDA Guidance on Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/P) governs these products. Medicare coverage requires documented failure of conservative wound care × 30 days minimum.

Etiology-Directed Systemic Therapy

• Arterial revascularization: PTA/stenting, femoral-popliteal bypass, endarterectomy per AHA/ACC 2024 CLTI Guidelines; wound cannot heal without restoring perfusion
• Glycemic optimization: HbA1c <7% target for DFU healing; continuous glucose monitoring; multidisciplinary diabetic foot team
• Offloading: Total contact cast (TCC), removable cast walker (RCW), therapeutic footwear — mandatory for diabetic neuropathic ulcers; removes mechanical load from plantar ulcer
• Hyperbaric oxygen therapy (HBOT): HCPCS G0277 / ICD-10-CM Z41.89; indicated for selected Wagner Grade 3+ DFUs with demonstrated hypoxia; requires authorization
• Calciphylaxis-specific: Sodium thiosulfate IV, cinacalcet, parathyroidectomy consideration; wound care primarily supportive
• Pyoderma gangrenosum: Systemic immunosuppression first (prednisone, cyclosporine, infliximab); wound debridement is contraindicated (worsens by pathergy)

Multidisciplinary Team

Optimal outcomes for complex non-healing wounds require: wound care nurse/NP, vascular surgery, endocrinology (DFU), podiatry, orthopedic surgery (osteomyelitis), infectious disease (infected wounds), and social work (adherence, home care coordination). The ADA 2024 Standards of Care Section 12 mandates multidisciplinary team management for complex DFUs.

🎓 17. Patient Education / Summary

For Patients and Families

A chronic skin ulcer (non-healing wound) is an open wound that has not healed in 4–6 weeks despite basic wound care. Unlike pressure sores (which come from lying or sitting in one position too long) or varicose vein wounds, these wounds may be caused by poor blood circulation in the arteries, diabetes-related nerve damage, or inflammatory conditions.

Key Points for Patients

• Blood sugar control is critical: If you have diabetes, keeping your blood sugar in range dramatically improves wound healing. Work with your care team to optimize your HbA1c. Visit American Diabetes Association — Foot Care for guidance.
• Check your feet daily: Inspect the bottom and sides of both feet every day using a mirror. Neuropathy (nerve damage) means you may not feel a wound forming.
• Protect your feet: Never walk barefoot if you have diabetes or poor circulation. Wear properly fitting therapeutic shoes.
• Keep wound appointments: Chronic wounds must be assessed regularly — missing appointments can allow rapid deterioration. Depth can progress from skin level to bone in days if untreated or infected.
• Report warning signs immediately: Increased redness, warmth, swelling, cloudy discharge, fever, or sudden increase in pain should prompt immediate contact with your wound care team or emergency care.
• Offloading matters: If you are instructed to use a special boot (total contact cast or removable cast walker), wear it as directed — taking it off to “rest” eliminates its benefit and delays healing.
• Smoking cessation is essential: Tobacco causes arterial constriction, severely impairing circulation to wounds. Visit Smokefree.gov for cessation resources.
• Nutrition: Adequate protein (1.2–1.5 g/kg/day), vitamin C, and zinc support wound healing; consider dietitian referral.

When to Seek Emergency Care

Call 911 or go to the emergency department immediately if you notice: rapidly spreading redness/swelling, black/gray skin surrounding the wound (gangrene), a foul smell with gas bubbles (gas gangrene), fever over 101°F, confusion or rapid heart rate. These signs can indicate limb- or life-threatening infection.

Additional Resources

• American Diabetes Association — Foot Care
• Wound Care Centers — Diabetic Foot Ulcers
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Smokefree.gov — Tobacco Cessation

About this Guide

This Clinical Documentation Guide is published by CCO Academy and is intended for credentialed coding, CDI, and clinical documentation professionals. Content is updated for FY2026 ICD-10-CM (effective October 1, 2025). All code assignments should be verified against the official ICD-10-CM Tabular List, AHA Coding Clinic, and applicable payer-specific policies. This guide does not constitute legal, medical, or compliance advice.

Last reviewed: April 2026 · Next scheduled review: October 2026 (FY2027 update)