Adrenal Collision Tumors: A Practical Application of the Existing Evidence.

Adrenal collision tumors (ACTs) are rare lesions in which two histologically distinct tumors coexist within the same adrenal gland. They are almost always incidental findings, and although their heterogeneous, dual-component appearance can raise concern for malignancy, they seldom represent a distinct clinical problem. The principal pitfall they create is radiologic rather than biochemical: the mixed composition of an ACT renders the adrenal CT washout protocol unreliable and can mimic a neoplasm. The established adrenal incidentaloma pathway (biochemical exclusion of pheochromocytoma and adrenocortical carcinoma, imaging phenotyping, and size- and growth-based surveillance) reliably identifies both a functional and a malignant component of a collision tumor . Drawing on institutional experience and the published case literature, this narrative review describes the entity and its imaging caveats, and shows how the standard pathway can be applied to risk-stratify low-risk lesions and avoid unnecessary surgery while selecting appropriate first-line imaging.