Epidermal cyst in sternomastoid muscle simulating a malignant growth

Abstract

Epidermal Cysts are slow growing, elevated, round, firm, intracutaneous or subcutaneous tumours varying from 0.2 to 5 cm in diameter. They are usually located in the exposed surfaces of the body, but may be located anywhere. Histologically, they have a wall composed of true epidermis. In young cysts several layers of squamous and granular cells can be recognised but in older cysts the wall is atrophic and usually contains one to three layers of flattened cells. The Cyst is filled with keratin which is frequently arranged in laminated layers. Rarely foci of calcification are found. If the Cyst ruptures and the contents reach the dermis a considerable foreign body giant cell reaction results, (Lever, 1967). In the present communication, we are going to report an unusual case of epidermal cyst in sternomastoid muscle in a male aged 43 years which clinically resembled a malignant growth. To the best of our knowledge, a similar case has not been reported in the past.