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What’s under your skin? Lumps and Bumps Decoded

While dermatologists are experts in the skin, hair and nails, did you also know that our expertise extends to those layers beneath? There are numerous growths, lumps, and bumps that can exist in these layers, and because they can’t be seen directly, only felt, they can be more difficult to diagnose than other skin lesions.

In this blog, we’ll get you familiar with common “lumps” under the skin and when you should seek out medical advice to diagnose and treat them.

A hand with a visible cyst using a mouse

The Layers of Your Skin

The epidermis is the surface layer that we can see and feel, but your integumentary system (fancy term for the organs that cover our body, aka skin) also consist of a middle layer, the dermis, and a deep layer, the subcutis.

The dermis mostly consists of the collagen that gives our skin strength and support. The subcutis is the deep layer that goes down to the underlying muscle, bone, or cartilage, and mostly consists of fat.


A cyst is a growth on the body that consists of a growing sack that accumulates fluid or other material inside. In the skin, the most common type of cyst is called an epidermal inclusion cyst. It typically presents as a mobile, soft to rubbery, nodule under the skin.

These are slow growing, and may not become apparent until after years of growth. Their size varies from a few millimeters to the size of a tennis ball (internet worthy :). Often, they have a central pore and a cheese-like material can be expressed with gentle pressure (This is keratin, the remnants of broken-down skin cells).

While not dangerous, cyst do grow over time, and if they are traumatized, they can rupture under the skin resulting in a very painful inflammatory reaction much like an infection.

Because cysts do not resolve on their own, continue to enlarge over time, and become very painful if they rupture, we do recommend removal. Cysts can typically be removed by a fast, in-office surgical procedure that opens a hole above the cyst, allowing extraction of the cyst sack and contents, then repaired with a few sutures. Taking care of a cyst sooner than later can help avoid pain and scarring in the future by dealing with it while it is small and not ruptured.


Lipomas are common, benign tumors of fatty tissue that grow in the subcutaneous layer. Lipomas vary widely in their size and can occur almost anywhere on the body. They are very soft and mobile nodules under the skin. They can be isolated lesions or present with many lesions in some genetically predisposed individuals.

The good news is that cancerous versions of lipomas are incredibly rare. If they grow to the point that they are painful or cosmetically bothersome, an in-office surgical procedure to excise the lipoma can be done quickly and efficiently under local anesthesia.


An abscess is an infection of the deep layers of skin. Unlike cysts and lipomas, an abscess grows very quickly and can be quite painful. You should see a physician as soon as possible if you suspect you have an abscess. While antibiotics can be helpful, abscesses must be drained for a speedy resolution and to prevent infection from spreading.


Luckily, cancer of the deep layers of skin is unusual. There are myriad different cell types that inhabit the deep layers of skin, including sweat glands, oil glands, nerves, muscles, and hair follicles. All of these different cell types have cancers that grow from them. If you have a nodule that is very firm, tender, not mobile, or quickly growing, then you should seek medical advice as a biopsy may be necessary to determine a diagnosis.

During cancer screening exams, “what is this lump” is one of the most common questions we receive. If you have a questionable lump, then don’t hesitate to make an appointment with an expert.



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