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  2. ICD-10-CM Codes List
  3. C00–D49
  4. C76-C80
  5. Malignant neoplasm without specification of site (C80)

Malignant neoplasm without specification of site (C80)

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.

Instructional Notations

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

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

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)