Excludes1 pair
C96.5 vs C96.6
C96.5 and C96.6 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on C96.5
unifocal Langerhans-cell histiocytosis (C96.6)
C96.5
Multifocal and unisystemic Langerhans-cell histiocytosis
Billable
- Chapter 2
- Neoplasms
- Section
- C81-C96
Use when the record says
- Hand-Schüller-Christian disease
- Histiocytosis X, multifocal
Indexed under
- Hand-Schüller-Christian disease or syndrome
- Schüller-Christian disease or syndrome
- Syndrome › Schüller-Christian
- Xanthoma › bone (generalisata)
- Histiocytosis › X NEC › multifocal
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