C37
BillableMalignant neoplasm of thymus
HCC Category Mapping
V28HCC 21 — Breast, Prostate, Colorectal and Other Cancers and Tumors
0.545V24HCC 11 — Colorectal, Bladder, and Other Cancers
0.306ESRDHCC 11 — Colorectal, Bladder, and Other Cancers
0.000RxHCCHCC 22 — Cancer, Other Specified Sites
0.000What This Code Means
Cancer that develops in the thymus, a small gland located behind the breastbone that is part of the immune system.
Coding Tips
- •Thymic cancers are relatively rare; ensure documentation clearly indicates thymus as primary site
- •Do not confuse with thyroid cancer (C73)
Clinical Significance
Thymic cancer is rare, with thymomas being the most common type. These tumors are significant in risk adjustment because they are often associated with paraneoplastic syndromes, most notably myasthenia gravis, which adds complexity to patient management. Thymic carcinomas are more aggressive than thymomas and carry a worse prognosis.
Documentation Requirements
- ✓Pathology confirmation distinguishing thymoma (types A, AB, B1, B2, B3) from thymic carcinoma
- ✓WHO histological classification and Masaoka-Koga staging
- ✓Assessment for paraneoplastic syndromes (myasthenia gravis, pure red cell aplasia, hypogammaglobulinemia)
- ✓Imaging showing thymic origin in the anterior mediastinum
- ✓Resection status (complete vs. incomplete)
Excludes 1 — Do NOT code together
- malignant carcinoid tumor of the thymus (C7A.091)
Commonly Confused Codes
C73 — Thyroid cancer: 'Thymus' and 'thyroid' are easily confused in documentation — verify anatomical siteC38.1 — Anterior mediastinum: Thymic tumors are in the anterior mediastinum; if documented as 'anterior mediastinal mass,' query for thymic originD15.0 — Benign neoplasm of thymus: Some thymomas are benign; confirm malignancyC85.1 — Unspecified B-cell lymphoma: Mediastinal lymphomas may mimic thymic tumors
Code Hierarchy
└C37Malignant neoplasm of thymus
└C37Malignant neoplasm of thymus