A nondiagnostic bone biopsy sample is most often due to sampling which part of the lesion?

• A. Periosteal reactive bone
• B. Medullary cavity
• C. Soft tissue
• D. Epiphysis

Answer: (A)

Sampling the periosteal reactive bone tends to be nondiagnostic because this tissue is a reactive, non-neoplastic rim that forms in response to an underlying lesion. It often contains primarily new bone, fibrous tissue, and inflammatory cells rather than the actual pathological tissue (tumor cells or infectious organisms) driving the lesion. The diagnostic tissue is usually within the lesion itself—in the medullary cavity or the internal tumor mass (or its soft-tissue extension). Therefore, targeting the periosteal surface tends to miss the true pathology, leading to nondiagnostic results. When possible, biopsy should be directed toward the center of the lesion or areas of cortical destruction with imaging guidance to capture the actual disease process.