Solitary bone cyst, unspecified pelvis

This code signifies the presence of a single, benign, fluid-filled lesion within the bone structure of the pelvis, where the specific location within the pelvis is not documented. These cysts are typically asymptomatic and often discovered incidentally on imaging studies. They represent a localized area of bone resorption and replacement by fibrous tissue and fluid.

Use this code when documentation confirms a solitary bone cyst located in the pelvis, and no further specificity regarding the exact pelvic bone (e.g., ilium, ischium, pubis) is provided. This code is appropriate when imaging reports (X-ray, MRI, CT) describe a unilocular, lytic lesion consistent with a simple bone cyst in the pelvic region without specifying the exact bone.

• Ensure the documentation explicitly states "solitary" or "simple" bone cyst to differentiate from other bone lesions.
• Avoid using this code if a more specific anatomical site within the pelvis (e.g., ilium, ischium) is documented; instead, use the appropriate M85.45- subcategory.
• Do not use this code for aneurysmal bone cysts (M85.5-) or other types of bone tumors.