Leaked epidermal inclusion cyst - arm

Case contributed by Dr Maulik S Patel


Left proximal arm region swelling for about 20 years. Presented with complaints of local pain with a discharge for the past month.

Patient Data

Age: 70 years
Gender: Male

There is a well-defined, encapsulated lesion with mobile internal echoes in the region of interest. The lesion is in the subcutaneous plane and abuts skin. It shows a tiny hypoechoic track to the skin. There is a posterior acoustic enhancement. The lesion measures about 45 x 41 x 29 mm. There is a breach of the capsule at the caudal end of the lesion with an extralesional collection of about 17 x 12 x 10 mm. The adjacent subcutaneous fat and skin show edema.

Case Discussion

The case shows a classic history and ultrasound findings of an epidermal inclusion cyst. The patient had a palpable lesion for many years without any pain in the left arm region. The leak from the lesion resulted in local pain and discharge. Ultrasound shows an encapsulated lesion with avascular contents in the subcutaneous plane abutting the undersurface of the skin and shows a punctum (tiny track from the lesion to the skin). There is a capsule breach in the lesion causing local inflammation.

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