An Intramuscular Epidermal Cyst of Erector Spinae Muscles: A Case Report

An intramuscular epidermal cyst without subcutaneous involvement is extremely rare. The patient presented with low back pain. Spinal magnetic resonance imaging indicated spindle-shaped mass in the right erector spinae muscles located at L3 to L5 level without any connection with subcutaneous tissue. The patient underwent operation for removal of intramuscular cystic lesion. The tumor was totally removed and pathologically confirmed with epidermal cyst. Unlike typical epidermal cyst, the patient had a characteristic clinical manifestation of mild low back pain without palpable mass and local tenderness.