Cysts and lipomas are benign lumps of the superficial tissues, but they differ in origin, structure and consistency. Sebaceous (epidermoid) cysts result from blockage of a sebaceous gland: they are firm or elastic, well defined, filled with sebum and keratinous material and often prone to inflammation, with redness, pain and sometimes discharge. Lipomas, on the other hand, are soft, mobile nodules that can easily be moved under the fingers, caused by a localised accumulation of fatty tissue; they may be single or multiple and in some cases extend deeper, down to the muscle layer.

Diagnosis is based on a dermatological and/or surgical examination, with palpation and clinical assessment, and is often supported by skin and subcutaneous ultrasound. Ultrasound helps confirm whether the lesion is cystic or lipomatous and defines its size, depth and relation to surrounding structures, allowing the physician to plan any surgical removal more safely. When there is diagnostic uncertainty, the removed tissue is sent for histological examination to confirm its benign nature.