ICD-10 Code C38 – Malignant neoplasm of heart, mediastinum and pleura (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C38 – Malignant neoplasm of heart, mediastinum and pleura
What it is
C38 identifies a malignant tumor arising in the heart, mediastinum, or pleura. Use it when the record documents primary cancer in one of these thoracic sites.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include chest symptoms, mass effect, or imaging evidence of a malignant lesion in the specified anatomic site.
When to use this code
Use C38 when the provider documents a primary malignant neoplasm of the heart, mediastinum, or pleura. It also fits when pathology, imaging, or operative notes clearly identify one of these sites as the cancer origin.
If the record only says “thoracic mass” or “metastatic disease,” check documentation before coding. Make sure the site and primary nature of the malignancy are explicit.
Do not use for
Do not use C38 for secondary malignant neoplasms, benign tumors, or nonspecific chest lesions. Check documentation if the cancer site is uncertain or if another primary site is stated.
Coding tip
Confirm both the anatomic site and that the neoplasm is primary before assigning C38.