Malignant neoplasm of other parts of mediastinum

This code signifies a cancerous growth originating in various unspecified or less common areas within the mediastinum, the space between the lungs. This includes malignant tumors affecting structures such as the mediastinal lymph nodes, connective tissue, or other unclassified sites within this region.

Apply this code when documentation confirms a primary malignant neoplasm located in a mediastinal site not specifically classified elsewhere (e.g., not thymus, heart, or great vessels). This code is appropriate when the pathology report or physician's diagnosis explicitly states "malignant neoplasm of other parts of mediastinum" or specifies a mediastinal location without a more precise ICD-9-CM code.

• Ensure the documentation specifies "malignant" to differentiate from benign or uncertain behavior neoplasms.
• Always review for more specific codes within the 164 series (e.g., 164.0 for thymus, 164.1 for heart) before defaulting to this code.
• If the primary site is unknown but metastasis to the mediastinum is present, code the primary site first, followed by the appropriate secondary malignancy code.