histologic aspects of Paget's disease are characterized by an alteration
in osteoclastic activity, which results in an accelerated rate of
bone resorption, and increased osteoblastic activity. In this slide,
a hematoxylin and eosin-decalcified stained section shows an active
lesion of Paget's disease with large, multinucleated osteoblasts.
One osteoclast has at least 50 nuclei. Multinucleation is striking
and typical of Paget's disease. Also, numerous osteoblasts are repairing
bone previously resorbed by the osteoclasts. The marrow is grossly
abnormal with an intensely fibrovascular appearance that is typical
of active disease.