Malignant neoplasm without specification of site (C80) ICD-10-CM
The C80 code range covers malignant neoplasm without specification of site with 4 ICD-10-CM diagnosis codes. 3 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- malignant carcinoid tumor of unspecified site C7A.00
- malignant neoplasm of specified multiple sites- code to each site
Codes in the C80 Range 4 codes · 3 billable
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the C80 range.
Breakthrough Pain
Acute pain that comes on rapidly despite the use of pain medication.
Cachexia
General ill health, malnutrition, and weight loss, usually associated with chronic disease.
Chylothorax
The presence of chyle in the thoracic cavity. (Dorland, 27th ed)
Dermatomyositis
A subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. The illness occurs with approximately equal frequency in children and adults. The skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. The disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. The childhood form of this disease tends to evolve into a systemic vasculitis. Dermatomyositis may occur in association with malignant neoplasms. (From Adams et al., Principles of Neurology, 6th ed, pp1405-6)
Polymyositis
Diseases characterized by inflammation involving multiple muscles. This may occur as an acute or chronic condition associated with medication toxicity (DRUG TOXICITY); CONNECTIVE TISSUE DISEASES; infections; malignant NEOPLASMS; and other disorders. The term polymyositis is frequently used to refer to a specific clinical entity characterized by subacute or slowly progressing symmetrical weakness primarily affecting the proximal limb and trunk muscles. The illness may occur at any age, but is most frequent in the fourth to sixth decade of life. Weakness of pharyngeal and laryngeal muscles, interstitial lung disease, and inflammation of the myocardium may also occur. Muscle biopsy reveals widespread destruction of segments of muscle fibers and an inflammatory cellular response. (Adams et al., Principles of Neurology, 6th ed, pp1404-9)
About the C80 Code Range
ICD-10 code C80 covers malignant neoplasms without a specified site, including subcategories for disseminated and primary malignancies not classified by location. These codes are applied when the exact origin of cancer is unknown or when malignancy involves transplanted organs.
The main code, C80, designates a malignant tumor with no identified body site. Subcode C80.0 is used for widespread, disseminated cancers also known as carcinomatosis or metastatic small cell neuroendocrine carcinoma, useful when multiple metastatic cancers are present but the primary site remains unknown. This helps medical coders identify "disseminated malignant neoplasm" or synonyms like "multiple malignancy" when precise tumor origin is unclear. The C80.1 code represents a malignant primary tumor that is unspecified, covering a broad spectrum of tumors such as basaloid squamous cell carcinoma or adenocarcinoma when the exact location is not determined. It includes metastatic disease to various organs per its extensive synonyms and guides coding when primary site details are unavailable. Finally, C80.2 applies to malignancies arising in transplanted organs, including terms like post-transplant neoplasia and donor-derived melanoma, signaling cancers related to organ transplants.
Questions About This Page
How many billable codes are in the C80 range?
Of the 4 codes in this range, 3 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the C80 range classify?
The range classifies malignant neoplasm without specification of site. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
