Acute calcific tendinitis of the rectus femoris associated with intraosseous involvement: a case report with serial CT and MRI findings.

Acute calcific tendinitis of the shoulder is a well-known condition, but it is rare in the rectus femoris origin. Mostly reported cases were occurred in the reflected head of the rectus femoris, and only few cases were in the direct head of the rectus femoris. Intraosseous marrow involvement of calcific tendinitis is a more rare condition; it often goes misdiagnosed as an infection or a neoplasm. We report a rare, unusual case of acute calcific tendinitis of the direct head of the rectus femoris associated with intraosseous marrow involvement of calcification in anterior inferior iliac spine with serial CT and MRI findings. Aggressive osseous change may occur in acute calcific tendinitis of the rectus femoris as in this case which should be made an appropriate diagnosis to avoid unnecessary investigation and overtreatment like a surgery.