61/F Palpable mass in left shin,

trauma history(-)

61/F Palpable mass in left shin, trauma history(-)

T2WI

T2WI

T1WI

Gd-enhaned T1WI

Answer

•Hernia of tibialis anterior muscle

Findings

• defect of muscle fascia• Anterior bulging and herniation of tibialis anteri

or muscle

Discussion

• A muscle hernia is a focal protrusion of muscle tissue through a defect in the deep fascial layer.

• Common disorder in the leg, especially involving the middle and lower thirds.

• The tibialis anterior hernia is the most frequent, although involvement of the extensor digitorum longus, peroneus brevis, and gastrocnemius have also been reported.

• Usually present in athletes, soldiers, and in professions requiring great strain on the legs.

Discussion

• Usually asymptomatic subcutaneous nodule or mass that vary in size depending on position.

• Traumatic: direct (fascial injury) and indirect (injury to contracted muscle) types.

• Constitutional: may be due to a congenital defect in the fascia.

• MRI, CT, and ultrasonography have been used to identify the fascial defect.

• Treatment: longitudinal fasciotomy

References

1. JM Mellado, LP Palomar. Muscle hernias of the lower leg: MRI findings. Skeletal Radiol (1999) 28:465-469

2. JE Lane, CM Woody, JL Lesher. Tibialis Anterior muscle herniation. Dermatol Surg 28:7:July 2002

3. JC Lee, Jeremiah Healy. Sonography of lower limb muscle injury. AJR (2004) 182:341-351

4. Anil Agarwal, Rachna Agarwal. Abnormal presentation of tibialis anterior herniation. Eur J Orthop Surg Tarumatol (2006) 16:271-272