<prompt> Salt-pepper skull is a feature of ?Pagets syndromeEosinophilic granulomaPrimary hyperparathyroidismMultiple myeloma  <response>: Ans. is c i.e., Primary hyperparathyroidism Radiological features of primary hyperparathyroidism X-ray features of primary hyperparathyroidism are : ? Irregular, diffuse rarefaction of the bones. Salt pepper appearance : The skull bones show a well-marked stippling, but the opaque areas are small pin head size. Loss of lamina dura: A tooth socket is made up of thin coical bone seen as a white line surrounding the teeth. This is called the lamina dura. It gets absorbed in hyperparathyroidism. Sub-periosteal resorption of the phalanges is a diagnostic feature of hyperparathyroidism generalized variety. Resorption may also occur at lateral end of the clavicle. Spine shows central collapse of the veebral body and biconvex discs. Pelvis and other bones show coarse striations with clear cyst-like spaces. Brown s tumour is an expansile lytic lesion, which appears like a bone tumour, generally affecting the maxilla mandible. Extra-osseous radiological features such as renal calculi etc. may be present. 