​Difference between subcutaneous cyst and lipoma

Subcutaneous cysts are located in the dermis or subcutaneous tissue. They are cystic and have a capsule membrane with a thin liquid film inside. The surface is smooth and not adhered to the surrounding tissue. They are often semicircular spheres protruding from the surface. Subcutaneous cysts are often confused with lipomas in clinical practice. Generally, they can only be specifically distinguished during surgical resection. So what is the specific difference between subcutaneous cysts and lipomas? What does a lipoma look like?

Sebaceous cyst, commonly known as "sebaceous tumor", refers to the formation of cysts due to accumulation of sebaceous glands in the gland after the sebaceous gland duct is blocked. This is the most common type of benign skin tumor. Many people have experienced cysts, especially young people who are in their growth and development period.

Sebaceous cysts are most common on the scalp and face, followed by the trunk. Because of their different depths and different amounts of contents, their sizes are different and the gap is very large. Some are as small as a grain of rice and some are as large as an egg. It is often diagnosed as lipoma, fibroma, etc. Sebaceous cysts grow very slowly but patients can still feel them gradually increasing in size.

Sebaceous cysts are mostly single, occasionally multiple, round in shape, of medium hardness or elasticity, and protrude above the skin surface. When pushed, they feel connected to the surface but have no adhesion to the base and no sense of fluctuation. The skin color may be normal or light blue. If the enlargement is too rapid, the surface of the skin may appear shiny. Sometimes there is an opening on the skin surface through which the white tofu-like contents can be squeezed out. This opening is the opening leading to the sebaceous glands on the skin surface. The depression of the opening is caused by insufficient length of the duct. Sebaceous cysts often become infected, causing the cyst to rupture and temporarily disappear, but they will form scars and are prone to recurrence. The chances of a sebaceous cyst becoming cancerous are extremely rare.

Surgery is the only treatment for sebaceous cysts. During the operation, a fusiform skin incision can be designed along the skin grain direction to remove the cyst together with the skin connected to the cyst, especially when the duct opening is seen. When separating, special care should be taken as the cyst wall is very thin and should be removed as completely as possible. If the cyst wall remains, it is prone to recurrence. If there are symptoms of inflammation such as redness, swelling, heat and pain before surgery, the inflammation should be controlled first and then surgery should be arranged.

Treatment principles

1. Surgical resection: Once diagnosed, the cyst should be completely removed surgically.

2. Patients with concurrent infection should be given oral antibiotics (such as enhanced sulfamethoxazole, methylenediamine, etc.) and hot compresses and other anti-inflammatory treatments, and then surgical resection should be performed after the inflammation subsides.

Sebaceous cyst excision surgery should be performed by making a fusiform incision on the skin with the cyst blackhead as the center and completely removing it. In order to prevent the duct from being cut and the cyst from being ruptured, and to remove excess skin to make the local skin smooth after the operation, a fusiform incision must be made with the small blackhead as the center and the diameter of the lump as the incision length, combined with the skin texture of the sebaceous cyst. After incising the epidermis, if the cyst is small, the cyst and the normal skin tissue outside the cyst wall will be removed together; if the cyst is large, it should be separated to the cyst wall and peeled carefully along the cyst wall to try to completely remove the cyst. Because the cyst wall is very thin, if it is accidentally torn, you must be careful to remove the entire cyst wall to avoid postoperative recurrence.