Age / Sex : 53 / F

Chief complaint :

Left proximal thigh pain

What is your impression?
Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy of Hoseok Lee, Kyungpook National University Hospital

Discussion

Answer:  

Calcific tendinitis of gluteus maximus

Findings:

 Small nodular and irregular calcification in the posterior aspect of the proximal shaft of the left femur is seen on plain radiograph. Axial and sagittal reformatted CT images show calcification adjacent to cortex at gluteus maximus tendon attachment. MR images show soft tissue edema surrounding calcification.

Differential Diagnosis:

Juxtacortical osseous or cartilaginous tumor

Myositis ossificans

Discussion:

Calcific tendinitis is common and is related to the pathologic deposition of calcium hydroxyapatite crystals within the tendons. Calcific tendinitis is a dynamic process that evolves through several stages. Successive stages have been characterized as having distinct radiographic and pathologic features, which often correlate with clinical symptoms. When the calcifications are fluffy and amorphous, this can indicate the resorptive phase of calcific tendinitis, which is often associated with clinical symptoms of pain and reduced mobility. In this phase, patients may be suspected of having other pathology, such as septic arthritis or fracture. The imaging findings of calcific tendinitis in this stage may include aggressive osseous changes as well as extensive soft tissue oedema. These findings can be especially striking on cross-sectional modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI). Visualizing tendon calcifications can prevent mistaking calcific tendinitis for more aggressive disorders. Radiographs can be especially helpful, even after initial imaging with MRI or CT.

 Calcific tendinitis of the gluteus maximus tendon is a rare but classical site of calcific tendinitis. Osseous erosion or reconstruction may reflect repetitive traction force at the insertion point of the gluteus maximus muscle. It has been suggested that erosion may be due to mechanical effect of pull of the muscle at the inflamed insertion or to increased local hyperemia. Underlying osseous erosion or reconstruction is infrequent and seems to occur particularly in unusual sites. Although the atypical location and osseous erosion may lead to a diagnosis of malignancy, clinical symptoms and the absence of significant soft tissue mass should provide the right diagnosis. The differential diagnosis includes malignant cartilaginous tumor, malignant osseous tumor, and myositis ossificans traumatica. Either CT or MRI can suggest the right diagnosis when the anatomical location of the lesion is at the insertion point of a tendon and when there is no mass effect in the surrounding soft tissues.

References:

1. Hottat N, Fumiere E, Delcour C. Calcific tendinitis of the gluteus maximus tendon: CT findings. Eur Radiol 1999;9:1104-1106


2. Siegal DS, Wu JS, Newman JS, Del Cura JL, Hochman MG. Calcific tendinitis: a pictorial review. Can Assoc Radiol J 2009;60:263-272