ICD-10 Code C49.8 – Malignant neoplasm of overlapping sites of connective and soft tissue (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C49.8 – Malignant neoplasm of overlapping sites of connective and soft tissue
What it is
C49.8 identifies a malignant tumor arising in connective or soft tissue when the primary site spans overlapping anatomical areas and cannot be assigned to a single, more specific site.
Clinical signs
Clinical features vary; refer to documentation. You may see a growing soft tissue mass, pain, swelling, or functional limitation, but diagnosis depends on pathology and site description.
When to use this code
Use this code when the record documents a malignant neoplasm of connective or soft tissue involving overlapping sites, such as a tumor crossing adjacent anatomic regions. It is appropriate when the provider cannot assign a more specific site code. Check documentation for histology and exact location.
Do not use for
Do not use it for benign soft tissue tumors, uncertain or unspecified masses, or malignancies with a clearly documented single primary site. If the site is known, choose the more specific code.
Coding tip
Confirm that “overlapping sites” is explicitly documented before assigning C49.8.