A pathological fracture occurs when a bone breaks due to a weakness in the structure caused by an abnormality or disease process. Causes of bone abnormalities include osteoporosis, malignant or non-malignant tumors, infection, and some inherited bone disorders.
Patients with a pathological fracture will present with symptoms similar to any fractured bone: swelling or bruising, deformity, pain in the area of fracture that is worsened with mobility or application of pressure, and loss of function of the injured area . Common anatomical sites for pathological fractures include the femur, vertebrae, humerus, and tibia  . Pain related to a fracture that onsets without an injury or trauma raises suspicion of a pathological fracture . Additionally, fractures in patients with pre-existing conditions such as metastatic cancer, advanced stage lung or breast cancer, Paget disease, osteoporosis/osteopenia, history of solid organ transplantation, chronic kidney disease may also indicate a pathological fracture.
A pathological fracture should always be included in the differential when patients with known bone metastases or a history of cancer complain of sudden onset of pain, even without swelling, deformity, or immobility. Pathological fractures of the thoracic or lumbar spine often present with pain upon sitting or standing. On the other hand, pathological spine fractures, particularly at the mid-back (the thoracic/lumbar junction), may present with pain when the patient is in a recumbent position. Cervical spine pathological fractures cause pain upon extension and flexion of the neck .
Workup of pathological fracture consists of a medical history (e.g., history of present illness, smoking history and other risk factors for lung, bladder, renal cancers, osteoporosis, previous fractures) . Laboratory and imaging tests can help identify the cause of the pathological fracture (e.g., metastatic disease or benign condition). A bone biopsy will provide a definitive diagnosis.
Laboratory tests :
A bone biopsy can be performed to determine the etiology of a pathological fracture (malignancy vs. insufficiency/benign disease process) . Most bone biopsies are performed by fine-needle aspiration. Other methods of obtaining a sample for bone biopsy includes surgical excision.