Discovering a lump beneath the skin can be concerning. Lipomas and cysts are common subcutaneous growths that, despite sometimes appearing similar, are distinct entities. Understanding their differences is important for accurate identification and appropriate management. This article clarifies the characteristics of lipomas and cysts, highlighting their key distinctions.
What is a Lipoma?
A lipoma is a non-cancerous growth of fatty tissue that typically forms just beneath the skin. These growths are generally soft to the touch, movable, and often feel doughy or rubbery. Most lipomas are painless, though some can cause discomfort if they press on nearby nerves or contain blood vessels.
Lipomas are slow-growing and usually range from 1 to 2 inches (3 to 5 centimeters) in diameter, though some can grow larger. They can appear almost anywhere on the body where fat cells are present, with common locations including the neck, shoulders, back, abdomen, arms, and thighs. As they are generally harmless and do not spread to surrounding tissues, treatment is usually not necessary unless they cause symptoms or cosmetic concerns.
What is a Cyst?
A cyst is a sac-like pocket of tissue that can contain various substances, such as fluid, air, pus, or semi-solid material. Unlike lipomas, cysts are surrounded by a distinct membrane or wall. Their texture can vary; some cysts feel firm, while others might feel softer, similar to a water-filled balloon.
Common skin-related cysts include epidermoid cysts, often found on the face, neck, and torso, and pilar cysts, frequently located on the scalp. Epidermoid cysts, sometimes referred to as sebaceous cysts, can develop a small dark pore (punctum) in the center. While most cysts are benign, they can become painful, inflamed, or infected, sometimes rupturing and causing discomfort.
How Lipomas and Cysts Differ
Lipomas and cysts differ fundamentally in their composition and origin. Lipomas are masses of mature fat cells, while cysts are sac-like structures filled with various contents like keratin, fluid, or pus. This difference contributes to their distinct tactile qualities; lipomas typically feel soft, rubbery, and doughy, while cysts can be firmer or more fluctuant.
Their mobility under the skin also varies. Lipomas are often highly mobile and feel “slippery” when pressed. Cysts, conversely, can have variable mobility; some are movable, while others may feel more fixed.
Cysts, particularly epidermoid cysts, may present with a central punctum, a feature absent in lipomas. Cysts are also more prone to inflammation, infection, or rupture, leading to redness, swelling, and pain, which is less common for an uninfected lipoma.
When to Consult a Doctor
Any new or changing lump warrants medical evaluation for accurate diagnosis. It is important to seek medical advice if a lump exhibits rapid growth or changes in size. A lump that becomes painful, tender, red, or warm to the touch could indicate inflammation or infection, necessitating prompt medical attention.
Concerns also arise if a lump feels unusually hard, is immobile, or has an irregular shape. Medical professionals typically diagnose these lumps through a physical examination. In some instances, additional diagnostic tools like ultrasound, MRI, or a biopsy may be used to confirm the lump’s nature and rule out more serious conditions. A healthcare provider can provide a definitive diagnosis and recommend the appropriate course of action.