|Title : Case 631|
Age / Sex : 49 / M
Chief complaint :
Mild firm and painful mass in left calf. (2 days ago)
Answer: Proliferative myositis
Lower leg MR;
T2-weighted spin-echo MR images of the left lower leg show a hyperintense soft-tissue mass in the belly of the medial head of gastrocnemius muscle preserving the muscle fibers. T1-weighted MR image demonstrate intermediate to subtle high signal intensity and almost homogenous enhancement.
Lower leg USG;
Irregular hyperechoic mass with intra-lesional hypoechoic line.
soft-tissue tumors, traumatic injury, myositis ossificans, muscle sarcoidosis, and various causes of infectious and inflammatory processes
Proliferative myositis(PM) is a rare benign inflammatory myopathy characterized by infiltration with basophilic giant cells and proliferative fibroblasts.
The keys to assigning the correct diagnosis are patient age, history of recent trauma, and a rapidly growing, firm and painful soft-tissue mass.
-Clinically, it presents as a very rapidly growing solitary soft-tissue mass, with or without pain.
-The etiology is unknown, but there is often a history of local trauma.
-It occurs most commonly in adults (mean age, 50 years), although it has been described in children.
-It usually arises in the trunk, head and neck region or in the upper extremities.
Ultrasonography and computed tomographic (CT) findings are nonspecific. CT usually reveals a mass that is hypo- or isoattenuating relative to the skeletal muscle, and contrast enhancement may be homogeneous, heterogeneous, or absent.
MR images of PM have been reported in several cases, with a hypo- or isointense T1 signal compared with that of muscle and homogeneous enhancement. T2-weighted MR images typically demonstrate a hyperintense soft-tissue mass.
Once the diagnosis has been established, the recommended follow-up strategy is no specific treatment, since PM may disappear spontaneously. Excision may be preferred to establish a diagnosis and for cosmetic reasons. Recurrence is extremely rare.
Radiology 2007; 244:613– 616. Case 118: Proliferative Myositis.
Skeletal Radiol. 2004; 33(4):237-240. Proliferative myositis in a patient with AIDS.
|Total applicants||32||Correct answers||2|
|장민영||국민건강보험공단 일산병원, 전문의|