Secondary malignant neoplasm of skin

This code signifies the spread of a primary malignant tumor from another body site to the skin. It indicates that the skin is a secondary location for cancerous growth, not the origin of the cancer. This metastatic process can manifest as new lesions or changes in existing skin conditions.

Apply this code when documentation clearly states a malignant neoplasm found on the skin is metastatic from a primary site elsewhere in the body. This diagnosis requires a confirmed primary malignancy and evidence of its spread to the integumentary system, often supported by biopsy results.

• Always code the primary malignancy first, followed by this code for the secondary skin involvement.
• Distinguish carefully between primary skin cancers and metastatic lesions; this code is exclusively for secondary involvement.
• Refer to the Excludes1 note to avoid coding secondary Merkel cell carcinoma with this code.