ICD-10 · PDGM grouping
C78 Secondary malignant neoplasm of respiratory and digestive organs
All 15 codes in the C78 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
15
Can lead a claim
12
Cannot lead a claim
3
What CMS assigns to C78
12 of the 15 codes group to MMTA - Infectious Disease, Neoplasms, and Blood-Forming Diseases; 3 are assigned no clinical group. 12 of the 15 count toward the Secondary Neoplasm of Respiratory and GI Systems comorbidity subgroup; 3 are assigned none. 12 of the 15 can lead a claim.
- Secondary Neoplasm of Respiratory and GI Systems: can award the low comorbidity tier as a secondary diagnosis.
Every code in C78
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| C78.0 Secondary malignant neoplasm of lung | ||||
| C78.00 | Secondary malignant neoplasm of unspecified lung | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
| C78.01 | Secondary malignant neoplasm of right lung | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.02 | Secondary malignant neoplasm of left lung | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.1 | Secondary malignant neoplasm of mediastinum | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.2 | Secondary malignant neoplasm of pleura | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.3 Secondary malignant neoplasm of other and unspecified respiratory organs | ||||
| C78.30 | Secondary malignant neoplasm of unspecified respiratory organCMS: Secondary malignant neoplasm of unsp respiratory organ | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
| C78.31 | Secondary malignant neoplasm of larynx | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.32 | Secondary malignant neoplasm of pharynx | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.39 | Secondary malignant neoplasm of other respiratory organs | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.4 | Secondary malignant neoplasm of small intestine | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.5 | Secondary malignant neoplasm of large intestine and rectum | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.6 | Secondary malignant neoplasm of retroperitoneum and peritoneumCMS: Secondary malignant neoplasm of retroperiton and peritoneum | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.7 | Secondary malignant neoplasm of liver and intrahepatic bile ductCMS: Secondary malig neoplasm of liver and intrahepatic bile duct | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
| C78.8 Secondary malignant neoplasm of other and unspecified digestive organs | ||||
| C78.80 | Secondary malignant neoplasm of unspecified digestive organ | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
| C78.89 | Secondary malignant neoplasm of other digestive organs | Can lead a claim | K | Secondary Neoplasm of Respiratory and GI Systems |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
The monthly home health regs digest
What CMS changed, what's due next, and what to do about it — one email a month, no fluff. Read the first issue