RECIST 1.0:

• Lesions considered to be truly non-measurable include the following: bone lesions, leptomeningeal disease, ascites, pleural/pericardial effusion, inflammatory breast disease, lymphangitis cutis/pulmonis, abdominal masses that are not confirmed and followed by imaging techniques, and cystic lesions.

RECIST 1.1:

• Lesions that meet radiographic criteria for simple cysts should not be considered as malignant lesions (neither measurable nor non-measurable)
• Radiographically indeterminate, complex "cystic" lesions should be considered non-measurable lesions
• "Cystic Lesions" thought to be cystic metastases can be considered as measurable lesions, if they meet the definition of measurability. However, if non-cystic lesions are present in the same patient, these should be preferably selected for assessment.