In simple words: Osteitis deformans in neoplastic diseases is a painful bone problem caused by cancer.It makes bones weak and misshapen. Doctors diagnose it with tests like X-rays and blood work, and treatment might include medication, physical therapy, or surgery.

Osteitis deformans in neoplastic diseases, also known as osteitis deformans in malignant neoplasm of bone, is a painful and debilitating condition characterized by weakened and deformed bones resulting from cancer, not trauma.It presents with bone pain, weakening, deformity, pathologic fractures, bowing of weight-bearing bones, and deformity of flat bones. Diagnosis involves patient history, physical examination, imaging (X-rays, MRI, PET, CT scans, DXA scans), blood tests (alkaline phosphatase, bone markers), and potentially a bone biopsy. Treatment options include weight-bearing reduction, orthosis use, medications (to inhibit bone loss or prevent resorption, analgesics), physical therapy, treatment of the underlying cancer, and surgical fracture repair.

Example 1: A 65-year-old male presents with severe pain in his left femur, accompanied by significant bone deformity. Imaging reveals a lytic lesion consistent with an osteosarcoma. The diagnosis of osteitis deformans in neoplastic disease (M90.6) is made, and the patient undergoes chemotherapy, followed by surgical resection of the tumor., A 72-year-old female with a history of breast cancer presents with back pain and progressive kyphosis.Bone scans and X-rays reveal multiple osteolytic lesions in the vertebrae, consistent with metastatic bone disease. The patient is diagnosed with osteitis deformans in neoplastic disease (M90.6) and is managed with bisphosphonates to reduce bone pain and fracture risk., A 58-year-old male presents with progressive skeletal pain and deformity.A bone biopsy reveals multiple myeloma.The patient is diagnosed with osteitis deformans in neoplastic disease (M90.6) along with the primary malignancy and treated with a combination of chemotherapy, radiation, and supportive care such as pain medication.

Detailed patient history including presenting symptoms, relevant past medical history (especially cancer history), and any prior treatments;Physical examination findings including location and extent of bone pain, deformity, and any neurological deficits;Results of imaging studies such as X-rays, CT scans, MRI, PET scans and DXA scans;Results of laboratory tests such as blood work (alkaline phosphatase, calcium, bone-specific markers);Pathology reports from bone biopsies (if performed);Documentation of treatment plan, response to treatment, and any complications.

** This code is used to describe osteitis deformans when it is a secondary condition arising from a neoplastic disease.It does not encompass primary osteitis deformans (Paget's disease), which is coded separately (M88).