Neoplastic diseases (including synovial sarcoma, osteosarcoma, and chondrosarcoma) and some degenerative disorders, such as calcified tendonitis, may also have similar radiological findings to those of FTC.14 If the patient has no history of the above-mentioned diseases and has a normal renal function, normal serum PTH, and 25-hydroxyvitamin D3 levels, heterotopic calcification secondary to the other diseases is unlikely. Here, PTH is linked to osteosarcoma.