Gluteus maximus calcific tendinopathy

Clinical History

A 53-year-old female presented to the Emergency Department with the acute onset of right hip pain without a history of trauma. Examination revealed marked tenderness generalised over the right buttock.

Imaging Findings

Frog leg projection of the right hip demonstrates an area of irregular calcification at the superior aspect of the diaphysis of the right femur with amorphous calcifications in the soft tissues (Fig. 1).

Contrast enhanced CT was performed for better characterisation which revealed occult soft tissue calcification along the posterior aspect of the linea aspera of the right femur, located at the site of the gluteus maximus muscle insertion (Fig. 2). On soft tissue windows, the soft tissue calcification is again demonstrated (Fig. 3).

Discussion

Calcific tendinopathy of the gluteus maximus muscle is an uncommon location for tendinopathy to occur, with only sporadic reports in the literature [1, 2].

Gluteal tendinopathy typically occurs more commonly in females than males with a mean age of approximately 60 years of age [2]. The clinical presentation is variable and can involve fever, swelling, local oedema, and pain so extreme that there is a limited range of motion [3]. Laboratory findings may include elevated levels of acute phase reactants.

Calcific tendinopathy can be categorised as acute or chronic in nature, with the acute tendinopathic process clinically lasting less than 2 weeks. The radiographic appearance may remain unchanged for many months. It is typically a self-limiting condition, although in the chronic process, the discomfort and pain has been known to last for 2 to 24 months [2, 3].

Gluteus maximus tendinopathy characteristically tends to occur at the distal tendon, and knowledge of this anatomy is important for understanding the imaging findings. The tendon inserts on along the dorsal aspect of the iliotibial band of the tensor fascia lata and also along the dorsal aspect of the femur distal to the greater trochanter at the linea aspera.

Imaging findings can include amorphous calcification and underlying osseous erosions. The differential diagnosis can include a malignant cartilaginous tumour, a malignant osseous tumour, or myositis ossificans. Knowledge of the characteristic location of this tendinopathy, as well as the clinical presentation is critical to avoid a misdiagnosis of malignancy.

The radiographic findings can suggest the correct diagnosis of gluteus maximus tendinitis when it occurs in this characteristic location and there is no underlying soft tissue mass [2, 4]. A bone scan may show localised uptake in the region of the calcification, although these characteristic radiographic findings usually make this study unnecessary [2, 4].

In summary, gluteus maximus calcific tendinopathy has a characteristic imaging appearance and location. Knowledge of the existence of this disease entity is crucial to avoid a potential misdiagnosis of malignancy.

Differential Diagnosis List

Final Diagnosis

Gluteus maximus calcific tendinopathy

URL:	https://www.eurorad.org/case/8382
DOI:	10.1594/EURORAD/CASE.8382
ISSN:	1563-4086