L10.9 ICD-10-CM Code: Pemphigus, unspecified
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the skin and subcutaneous tissue (L00-L99) / Bullous disorders (L10-L14)
L10.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidancePemphigus, unspecified
An autoimmune blistering disease where the immune system attacks the connections between skin cells, causing painful blisters and sores, but the specific type is not documented.
Buddy Insight
Pemphigus unspecified indicates an autoimmune blistering disease where the specific subtype has not been determined, requiring further diagnostic workup.
CMS-HCC V28
MappedHCC 387
RAF 0.262
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
MappedHCC 314
RAF 0.0
Code Trumping
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for L10.9 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for L10.9 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for L10.9 in this effective period.
Excludes 1
Official- pemphigus neonatorum (L01.03)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for L10.9 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for L10.9 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for L10.9 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is L10.9 an HCC code?
Yes. L10.9 maps to Pemphigus and Other Autoimmune Skin Conditions under the CMS-HCC V28 risk adjustment model.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for L10.9
For L10.9to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed L10.9 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
L10.9 is the ICD-10-CM diagnosis code for pemphigus, unspecified. An autoimmune blistering disease where the immune system attacks the connections between skin cells, causing painful blisters and sores, but the specific type is not documented. L10.9 sits in the ICD-10-CM chapter for diseases of the skin and subcutaneous tissue (l00-l99), within the section covering bullous disorders (l10-l14).
Under the CMS-HCC V28 risk adjustment model, L10.9 maps to Pemphigus and Other Autoimmune Skin Conditions (HCC 387) with a community, non-dual, aged base RAF weight of 0.262. L10.9 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is a default code used when pemphigus is diagnosed but the specific type cannot be determined from documentation. Because L10.9 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for L10.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a default code used when pemphigus is diagnosed but the specific type cannot be determined from documentation
- •Query the provider if additional clinical details are available to assign a more specific L10 code
Clinical Significance
Pemphigus unspecified indicates an autoimmune blistering disease where the specific subtype has not been determined, requiring further diagnostic workup. This diagnosis represents a serious autoimmune condition needing immunosuppressive therapy and subspecialty care.
Documentation Requirements
- ✓Clinical presentation with blistering consistent with pemphigus
- ✓Histopathologic evidence of acantholysis
- ✓Direct immunofluorescence showing intercellular deposits
- ✓Indication that specific subtype determination is pending
- ✓Assessment of disease severity and extent
- ✓Initial treatment approach
- ✓Plan for further diagnostic characterization
- ✓Monitoring for treatment response