J Korean Soc Radiol.  2018 Dec;79(6):354-358. 10.3348/jksr.2018.79.6.354.

Intramuscular Epidermal Cyst of the Buttock: A Case Report

• Yim Y
• Kim NR
• Moon SG

• KMID: 2427385
• DOI: http://doi.org/10.3348/jksr.2018.79.6.354

Abstract

Epidermal cysts are common benign subcutaneous lesions that occur in or on the skin. It is not very difficult to diagnose subcutaneous epidermal cysts using ultrasound imaging because they exhibit typical sonographic features. However, the differential diagnosis can be confused when epidermal cysts are found in unusual sites. The authors report a case involving a 4-year-old girl who presented with an intramuscular epidermal cyst in the gluteus maximus muscle. Magnetic resonance imaging revealed characteristic internal features of the epidermal cyst, despite being in an uncommon site, and was very useful in the preoperative diagnosis.

MeSH Terms

Buttocks*
Child, Preschool
Diagnosis
Diagnosis, Differential
Epidermal Cyst*
Female
Humans
Magnetic Resonance Imaging
Skin
Ultrasonography

Figure

• 

  Fig. 1 Intramuscular Epidermal Cyst of the buttock in a 4-year-old girl presented with a palpable mass in the right buttock. A. Ultrasound imaging revealing an ovoid hyperechoic mass with internal hyperechoic strands (short arrows) and posterior acoustic enhancement (arrowheads) in the gluteus maximus muscle on transverse scan. Acoustic shadowing by the ischial tuberosity (long arrow) is noted. B. Ten months later, a follow-up ultrasound reveals an increase in the size of the mass, with extension to the subcutaneous tissue. The anechoic cystic change is indicated at a focal bulging portion to the subcutaneous layer (arrow). C. Axial T2-weighted magnetic resonance image revealing a bright, hyperintense cystic mass in the right gluteus maximus muscle. The cyst includes internal hypointense debris (arrows) and the appearance of focal budding (arrowhead). D. Coronal T1-weighted magnetic resonance image revealing a slightly high-intensity signal of the mass at the inferomedial aspect of the buttock (arrow). E. Gadolinium-enhanced fat-suppressed T1-weighted image revealing peripheral rim enhancement and focal adjacent soft tissue enhancement (arrow). F. Hematoxylin and eosin stained microscopic section revealing several layers of slightly atrophic squamous epithelial-lining cyst (black arrows) filled with horny materials (arrowheads). Pathological findings were consistent with epidermal cyst (× 200).

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