Implantation dermoid

Case contributed by Dr Chris O'Donnell

Presentation

Slowly growing, painless mass in palmar aspect of the thumb. Cactus needle removed some months ago ? retained foreign body

Patient Data

Age: 85
Gender: Male
Modality: Ultrasound

Small, painless, apparently solid subcutaneous mass without blood flow could be a sebaceous cyst but an unusual location for such.   It is associated with a history of previous puncture wound but no foreign body is identified on ultrasound and no abnormal blood flow on colour Doppler to indicate an inflammatory mass or granulation tissue.

Case Discussion

This is an acquired condition that occurs as the result of implantation of epidermal fragments into the dermis by a penetrating injury.  The epidermis continues to grow and forms a cyst lined with stratified squamous epithelium and filled with keratin.

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Case Information

rID: 19515
Case created: 18th Sep 2012
Last edited: 5th Feb 2016
Inclusion in quiz mode: Included

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