What are the signs that complex kidney cyst is cancer?

Multiple features: Complex cysts, vs. Simple cysts, share common walls with other cysts, have solid components in the walls, or calcifications. The radiologist will opine if features look suspicious and either recommend a repeat ultrasound in 6 months, or a ct to further clarify.

Radiologic: Suspicious for malignancy if cyst appears irregular, if there are thick septations within cyst, calcifications, irregularities, polypoid or solid elements within cyst wall or septations. If complex cuts appears to be enlarging. Should be confirmed by ct with IV contrast if diagnosis is by ultrasound. Also needs 2B followed by serial ultrasound if early intervention is avoided.