With use of appropriate pulse sequences, MR imaging is an effective tool in the preoperative, noninvasive diagnosis of posterolateral rotatory instability.

With appropriate pulse sequences, unenhanced MR imaging of the shoulder is an accurate technique for the detection and localization of labral injuries.

Full-thickness anterior cruciate ligament graft tear can be differentiated from partial-thickness tear or intact graft by evaluating for graft fiber continuity (coronal plane), complete graft discontinuity (coronal plane), and graft thickness (coronal or sagittal plane).

Parachordoma is a rare soft tissue tumor that morphologically resembles chordoma of the axial skeleton but occurs in a peripheral site. A recent study reported immunohistochemical differences between chordoma and parachordoma. While both tumors were positive for cytokeratin (CK) 8/18 (as recognized by the antibody Cam5.2), S100 and epithelial membrane antigen (EMA), only the chordoma was positive for CK7, CK20, CK 1/5/10/14 (as recognized by the antibody 34betaE12) and carcinoembryonic antigen (CEA). It has since been suggested that tumors indistinguishable from chordoma that involve the periphery should be termed chordoma periphericum and that these tumors are distinct from parachordoma. In the current study, the clinical, radiological, pathological, immunohistochemical and ultrastructural features of a chordoma-like tumor involving the deep soft tissues of the lower leg of a 69-year-old woman are presented. Microscopically, the tumor had a pseudolobulated growth pattern and consisted of sheets, nests and cords of epithelioid cells, some with a physaliferous appearance, separated by abundant myxoid stroma. The tumor cells were positive for CK 8/18, EMA and S100, showed focal staining for CK7, and were negative for CK20, CK 1/5/10/14 and CEA. On the basis of these results a diagnosis of parachordoma was favored. For comparison, an immunohistochemical analysis of five axial chordomas was also performed. The chordomas showed positivity for CK 8/18 (5 of 5 cases), EMA (5 of 5 cases), S100 (5 of 5 cases), CK 1/5/10/14 (1 of 5 cases) and CK7 (1 of 5 cases). Stains for CK20 and CEA were negative in all five chordomas. The results of the present study suggest that the expression of antigens for CK 1/5/10/14, CK7, CK20 and CEA in chordoma might not be as common as what has been previously reported. The results also suggest that parachordoma might not be easily distinguished immunohistochemically from axial chordoma (and therefore also from so-called chordoma periphericum).