<prompt> Brown a tumour is seen inHypothyroidismHyperparathyroidismnoneall of the above  <response>: Browns tumour is seen in Hyperparathyroidism. Its an expansile lytic lesion. This is a collection of osteoclasts.It commonly found in maxilla and mandible, other bones also affected.Other features are multiple bone cysts, subperiosteal retraction of bones, salt and pepper appearance of the skull in X-ray. 