Abstract

Osteoid metaplasia is a rarely seen characteristic feature among all tumor types. Dystrophic calcification can be occasionally seen in necrotic areas of tumors However actual bone formation also termed as osteoid metaplasia or heterotopic bone formation is a rarely developed incidental microscopic finding.

In this case report we presented a case diagnosed as a high grade papillary urothelial carcinoma of the bladder associated with osteoid metaplasia, and another one with diagnosis of metastatic adenocarcinoma of colon

In both cases, presence of diffuse osteoid metaplasia accompanying malignant tumors is a remarkable finding. Two cases with incidentally detected osteoid metaplasia associated with different histopathological diagnosis were presented. Osteoid metaplasia is a rare entity which accompanies both benign and malignant tumors and its etiopathogenesis is still unknown. However osteoid metaplasia is an important incidental finding in that it can lead to misinterpretations as bone invasion when it accompanies malignant tumors.