This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Salt-pepper skull is a feature of ? 
Select and explain. 
A. Paget's syndrome, B. Eosinophilic granuloma, C. Primary hyperparathyroidism, D. Multiple myeloma
C: Primary hyperparathyroidism
Answer: C: Primary hyperparathyroidism 
Explanation: 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.