Alphabetic Index FY2027

C34.80

Malignant neoplasm of overlapping sites of unspecified bronchus and lung

FY2027Chapter 2: Neoplasms/C30–C39 Malignant neoplasms of respiratory and intrathoracic organs

BillableComplete code, valid to report
Care settingsHospital CCIPF Comorbidity · Oncology Treatment

C34.80 (also written C3480) is a billable ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of unspecified bronchus and lung. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 16 codes in category C34 (Malignant neoplasm of bronchus and lung). Its coding notes include a Use additional code instruction and 3 Excludes1 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

A primary malignancy code stays in use until treatment directed at that site is completed. After that, with no evidence of disease at the site, Z85 gives the former site.

Guidelines I.C.2.mCurrent malignancy versus personal history of malignancyRead the official text

Use additional code

Add the listed code as a secondary code, if known.

Inherited from C34 Malignant neoplasm of bronchus and lung
  • code to identify:
    • exposure to environmental tobacco smoke (Z77.22)
    • exposure to tobacco smoke in the perinatal period (P96.81)
    • history of tobacco dependence (Z87.891)
    • occupational exposure to environmental tobacco smoke (Z57.31)
    • tobacco dependence (F17.-)
    • tobacco use (Z72.0)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from C34 Malignant neoplasm of bronchus and lung
  • Kaposi's sarcoma of lung (C46.5-)
  • malignant carcinoid tumor of the bronchus and lung (C7A.090)
Also from chapter/block level (1 note)
Inherited from C30–C39 Malignant neoplasms of respiratory and intrathoracic organs

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Hospital CC

Counts as a complication or comorbidity (CC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 26 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C

IPF Comorbidity

On the CMS IPF comorbidity list.

Comorbidity categoryFactor
Oncology Treatment1.44
It counts as a comorbidity when reported as a secondary diagnosis and actively treated during the stay. An IPF receives only one adjustment within a category and can receive adjustments in more than one category.

Source: CMS IPF PPS FY 2027 final rule (CMS-1847-F), Addendum B-3 (comorbidity codes with adjustment factor); effective for discharges on or after October 1, 2026

Includes

Further defines or gives examples of the content of the category.

Also from chapter/block level (1 note)
Inherited from C30–C39 Malignant neoplasms of respiratory and intrathoracic organs
  • malignant neoplasm of middle ear

Notes

Also from chapter/block level (8 notes)
Inherited from Chapter 2 Neoplasms
  • Functional activity
  • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
  • Morphology [Histology]
  • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
  • Primary malignant neoplasms overlapping site boundaries
  • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
  • Malignant neoplasm of ectopic tissue
  • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).