C16.4 (Malignant neoplasm of pylorus) compared with D37.1 (Neoplasm of uncertain behavior of stomach), from the official CMS tabular data. C16.4 and D37.1 name the same anatomical site (prepylorus) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — uncertain behavior (prepylorus)
The behavior documented for the site — malignant primary, secondary, carcinoma in situ, benign, uncertain or unspecified — decides which column of the neoplasm table, and therefore which code, applies.
Source: CMS Table of Neoplasms
Same site, different neoplasm behavior. C16.4 and D37.1 name the same anatomical site (prepylorus) with a different neoplasm behavior.
From the CMS Table of Neoplasms: the behavior documented for that site — malignant primary, secondary, carcinoma in situ, benign, uncertain or unspecified — decides which column, and therefore which code, applies.
| C16.4Malignant neoplasm of pylorus | D37.1Neoplasm of uncertain behavior of stomach | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Malignant neoplasm of pylorus is a billable ICD-10-CM diagnosis code (C16.4). | Neoplasm of uncertain behavior of stomach is a billable ICD-10-CM diagnosis code (D37.1). |
| Includes | Malignant neoplasm of prepylorus Malignant neoplasm of pyloric canal | — |
| Use additional code | code to identify: alcohol abuse and dependence (F10.-) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources