Which condition is most likely to appear as a complicated cyst on a renal sonogram?

A malignant neoplasm is most likely to appear as a complicated cyst on a renal sonogram because these tumors can often present with irregular margins, internal vascularity, and septations. Unlike simple cysts, which are typically smooth, homogeneous, and anechoic, complicated cysts may include solid components, debris, or calcifications that are characteristic of malignancy. This complexity in appearance indicates an increase in the risk of cancer, making malignant neoplasms a significant consideration when evaluating renal cystic lesions.

In contrast, hypertrophied column of Bertin would typically appear as normal renal parenchyma without the complex features associated with a cyst. A simple renal cyst is defined by its uncomplicated, smooth, and anechoic nature, making it much easier to distinguish from a malignant process. Angiomyolipoma is a benign renal tumor that may appear as a complex lesion due to its fat content and vascularity, but it does not usually mimic the appearance of a complicated cyst as precisely as a malignant neoplasm would in terms of irregularity and potential aggressiveness.