Excludes1 pair
C45.1 vs C48-
C45.1 and C48 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 C45.1
other malignant neoplasm of soft tissue of peritoneum (C48.-)
C45.1
Mesothelioma of peritoneum
Billable
- Chapter 2
- Neoplasms
- Section
- C45-C49
Use when the record says
- Mesothelioma of cul-de-sac
- Mesothelioma of mesentery
- Mesothelioma of mesocolon
- Mesothelioma of omentum
- Mesothelioma of peritoneum (parietal) (pelvic)
Indexed under
- Mesothelioma › site classification › mesentery
- Mesothelioma › site classification › mesocolon
- Mesothelioma › site classification › omentum
- Mesothelioma › site classification › peritoneum
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