Explanation:
The patient's presentation of bone pain, nephrolithiasis ('stones, bones, groans, and psychiatric overtones'), and subperiosteal resorption on the radial aspect of the phalanges is pathognomonic for hyperparathyroidism. In severe cases, osteitis fibrosa cystica ('brown tumors') develops. Histologically, these are not true neoplasms but rather localized accumulations of fibrous tissue, proliferating fibroblasts, multinucleated giant cells (osteoclasts), and hemosiderin-laden macrophages (from microhemorrhages), which give the lesion its characteristic brown color. Reference: Campbell's Operative Orthopaedics, 14th Edition.