Explanation:
Paget's disease is characterized by a focal increase in bone turnover, driven by overactive, large, multinucleated osteoclasts. Pathological studies have frequently identified intranuclear and cytoplasmic inclusion bodies within these abnormal osteoclasts that closely resemble paramyxovirus nucleocapsids (specifically, measles virus or respiratory syncytial virus). While a definitive causal link remains debated, the paramyxovirus infection theory is a classic concept in the pathogenesis of Paget's disease. Reference: Miller's Review of Orthopaedics, 8th Edition.