ICD-10 Code D40.10 – Neoplasm of uncertain behavior of unspecified testis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D40.10 – Neoplasm of uncertain behavior of unspecified testis
What it is
D40.10 identifies a testicular mass or growth whose behavior is uncertain, meaning the record does not clearly show whether it is benign or malignant. Use it when the testis is documented as the site and the behavior remains unspecified.
Clinical signs
Clinical features vary; refer to documentation. Commonly, the chart may note a testicular lump, enlargement, or abnormal imaging finding, but the diagnosis must reflect uncertain behavior rather than a confirmed cancer.
When to use this code
Use D40.10 when the provider documents a neoplasm of uncertain behavior involving the testis and does not specify the side. It is appropriate for pathology or clinical notes that describe indeterminate behavior, pending workup, or an unresolved mass. Check documentation if the record later specifies benign or malignant behavior.
Do not use for
Do not use this code for confirmed malignant testicular neoplasms or clearly benign lesions. If the side is documented, use the more specific laterality code instead.
Coding tip
Confirm both behavior and laterality in the chart before assigning D40.10.