Which lesion is most likely subcutaneous and related to hair follicle contents?

• A. Sebaceous Cyst
• B. Simple Cyst
• C. Hematoma
• D. Gynecomastia

Answer: (A)

Sebaceous cysts form when a hair follicle or sebaceous gland becomes blocked, leading to accumulation of keratin and sebum inside the ducted follicle. This makes the lesion a superficial, skin- or subcutaneous-level structure that sits just beneath the epidermis and often feels mobile. On ultrasound it appears as a well-defined, superficial lesion in the subcutaneous tissue, sometimes with internal debris or keratin material and possibly posterior enhancement. This setting—subcutaneous location with contents derived from the hair follicle—fits a sebaceous cyst best.

In contrast, a simple cyst is a fluid-filled structure often located deeper in the breast parenchyma; a hematoma results from trauma and has variable echogenicity as it evolves; gynecomastia involves glandular breast tissue rather than a skin-origin lesion.