ICD-10 Code D40.12 – Neoplasm of uncertain behavior of left testis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D40.12 – Neoplasm of uncertain behavior of left testis
What it is
D40.12 identifies a neoplasm in the left testis whose behavior is uncertain. Use it when the record documents a testicular mass or tumor that is not yet confirmed as benign or malignant.
Clinical signs
Clinical features vary; refer to documentation. Commonly, the chart may note a painless testicular lump, swelling, or an incidental imaging finding that prompted further evaluation.
When to use this code
Use D40.12 when the provider documents an uncertain-behavior tumor of the left testis, such as a lesion awaiting pathology or definitive classification. You may also use it when the diagnosis is stated explicitly in the assessment or problem list. If later pathology confirms benign or malignant behavior, code the confirmed condition instead.
Do not use for
Do not use this code for clearly benign or malignant testicular neoplasms, or for symptoms alone without a documented neoplasm. Check documentation if the side is not specified.
Coding tip
Verify the laterality and the phrase “uncertain behavior” in the provider note before assigning D40.12.