In the initial, active phase of Paget’s disease of bone, which cell type demonstrates the most profound primary pathological abnormality?

Explanation:
Paget's disease begins with a focal initial lytic phase driven by intensely overactive, multinucleated osteoclasts that rapidly resorb bone. This is followed by a mixed compensatory phase of disorganized osteoblastic activity. Reference: Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism.