Epidermoid cyst in the upper arm

Case contributed by Digvijay Rane


The patient complains of nontender swelling in lateral aspect of arm since 4 years.

Patient Data

Age: 27
Gender: Female

A well defined, homogenous, oval lesion is seen in subcutaneous region in lateral aspect of upper arm. It appears hypointense on T1WI and hyperintense on T2WI and FS as well as STIR images and shows no obvious enhancement on postcontrast images.

The underlying deltoid muscle and humerus appear normal.

Case Discussion

Epidermoid cyst

  • Epidermoid cysts are also called as epidermal cysts or epidermal inclusion cysts.
  • These cysts occur due to proliferation of epidermal cells.
  • Multiple mechanisms are suggested in the formation of epidermoid cysts.
  • In some studies, HPV is also indicted in the etiology of these cysts.


  • It appears hypointense on T1WI and hyperintense on T2WI.
  • On T1FS images it shows suppression, while on post-contrast study it shows generally minimal peripheral enhancement with non-enhancing central part or may be entirely non-enhancing.

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