C96.0 vs C96.6
C96.0 and C96.6 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on C96.0
unifocal Langerhans-cell histiocytosis (C96.6)
C96.0
Multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis
Billable
- Chapter 2
- Neoplasms
- Section
- C81-C96
Use when the record says
- Histiocytosis X, multisystemic
- Letterer-Siwe disease
Indexed under
- Letterer-Siwe's disease
- Histiocytosis › acute differentiated progressive
- Reticuloendotheliosis › acute infantile
- Reticuloendotheliosis › nonlipid
- Reticulosis › acute of infancy (skin)
C96.6
Unifocal Langerhans-cell histiocytosis
Billable
- Chapter 2
- Neoplasms
- Section
- C81-C96
Use when the record says
- Eosinophilic granuloma
- Histiocytosis X, unifocal
- Histiocytosis X NOS
- Langerhans-cell histiocytosis NOS
Indexed under
- Granuloma › eosinophilic
- Histiocytosis › Langerhans' cell NEC
- Histiocytosis › X NEC
- Granuloma › bone › eosinophilic
- Granuloma › bone › lung
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027