Monostotic osteitis deformans of lumbar vertebra: A rare phenomenon in Eastern Asia

Osteitis deformans, also known as Paget’s disease, is characterized by accelerated osteoclastic activity followed by ineffective osteoblastic activity resulting in a deformed and fragile bone. It is more prevalent in Western Europe and relatively rare in Eastern Asia. It predominantly involves the lumbar spine, pelvis, and femur, frequently as polyostotic and rarely as monostotic disease. Here, we report a 64-year-old female, who presented with severe progressive back pain with no neurological symptoms. Radiographs revealed a picture frame L1 vertebra which was deformed and enlarged with loss of normal alignment. Magnetic resonance imaging revealed bone marrow changes involving all columns of L1 vertebra. Whole-body technetium-99 bone scan showed a solitary increased uptake of radioisotope by L1 vertebra. Considering the possibility of metastatic tumors, blood investigations were drawn for tumor markers which were within normal limits. A computed tomography-guided biopsy was done to facilitate diagnosis. Histopathology sections showed a mosaic pattern of bony trabeculae with multinucleated osteoclasts causing erosions and tunneling. A diagnosis of monostotic Paget’s disease was made which satisfactorily responded to single-dose zoledronic acid treatment. A comprehensive literature review is provided.