C79.89 vs D09.3

C79.89 (Secondary malignant neoplasm of other specified sites) compared with D09.3 (Carcinoma in situ of thyroid and other endocrine glands), from the official CMS tabular data. C79.89 and D09.3 name the same anatomical site (craniobuccal pouch) with a different neoplasm behavior. MedCoder-derived

Relationship

Informational

Neoplasm table relationship

C79.89

Secondary malignant neoplasm of other specified sites

↔

D09.3

Carcinoma in situ of thyroid and other endocrine glands

Same anatomical site, different neoplasm behavior.

Same site — carcinoma in situ (craniobuccal pouch)

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

Can these codes be reported together?

Same site, different neoplasm behavior. C79.89 and D09.3 name the same anatomical site (craniobuccal pouch) with a different neoplasm behavior.

From the CMS/CDC 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.

Side by side

	C79.89Secondary malignant neoplasm of other specified sites	D09.3Carcinoma in situ of thyroid and other endocrine glands
Billing status	Billable	Billable
Classification	C00-D49 — Neoplasms	C00-D49 — Neoplasms
Definition	Secondary malignant neoplasm of other specified sites is a billable ICD-10-CM diagnosis code (C79.89).	Carcinoma in situ of thyroid and other endocrine glands is a billable ICD-10-CM diagnosis code (D09.3).
Includes	—	Bowen's disease erythroplasia grade III intraepithelial neoplasia Queyrat's erythroplasia

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources