Eczema, dermatitis, atopy — what do these terms mean? Are they interchangeable? Different types of eczema are often described in terms that sound mysterious and complicated. However, the terms often are simply medical descriptions of otherwise well-known bodily processes, like sweating. Other terms are based on Latin or Greek words that describe particular symptoms. Why those two ancient languages? They were the common-ground languages of the scientific community when the condition was first defined.

Knowing more about the terms used to describe eczema can help you better understand your diagnosis and set you up for the best skin care possible.

Common Terms

Here’s a roundup of common terms you might encounter as you learn more about eczema.

Dermatitis and Eczema

The first thing to know is that eczema and dermatitis are interchangeable terms for the same irritating skin condition. “Derma” is the Greek word for skin, and “-itis” refers to inflammation. Put them together you get “dermatitis” — skin inflamation.

Allergen

An allergen is an otherwise harmless substance that a person’s immune system sees as dangerous or foreign. Allergens can cause an atopic reaction (or atopy) wherein the immune system overreacts to counter the offending intruders.

Asteatotic Eczema

If someone has “asteatosis,” their skin’s oil glands are not producing enough oil. Asteatotic eczema, therefore, is eczema related to such a decreased level of oils. Asteatotic eczema can also be referred to as “eczema cracquelée” — “craquelée” being French for “cracked,” which describes how this rash looks.

Atopic Dermatitis

Atopy is a condition in which a person’s immune system overreacts to common allergens. In atopic dermatitis, their body’s overreaction affects their skin, which also is likely to be compromised and thus a poor barrier to irritants. Other atopic conditions include allergic rhinitis (hay fever) and food allergies.

Contact Dermatitis

Contact dermatitis describes what happens to some people’s skin when they come in contact with something their body deems an allergen. Although it does involve an immune system reaction to an allergen, contact dermatitis is different from atopic dermatitis because it usually goes away quickly and, as long as you stay away from the offending allergen, it doesn't recur. Pet dander, soap, certain jewelry metals, and poison ivy and poison oak are all common skin allergens that can cause contact dermatitis.

Dyshidrotic Eczema

The word “dyshidrosis” stems from the Greek words for sweat (“idros”) and abnormal (“dys”). When dyshidrotic eczema was initially defined in the 19th century, a British dermatologist thought that poorly functioning sweat glands caused the tiny blisters on the palms, soles, fingers, and toes that are characteristic of this type of eczema. We now know that there are other triggers for dyshidrotic eczema as well, such as stress, fungal infection, and reaction to irritants.

Dyshidrotic eczema is also known as pompholyx eczema. (“Pompholyx” is Greek for “bubble.”) Early scientists studying this type of eczema thought that eczema blisters looked like bubbles, thus the name.

Neurodermatitis

The prefix “neuro-” refers to the nervous system. (And remember: “Derma” is the Greek word for skin, and “-itis” refers to inflammation.) While the cause of neurodermatitis isn’t known, it earned its name because it might be linked to a nervous system reaction or to emotional stress or triggers. Neurodermatitis causes itchy, dry skin patches that thicken and become leathery.

Neurodermatitis can be related to what’s sometimes called lichen simplex dermatitis. Outside the medical world, a lichen is a scaly, papery growth that can appear on rocks and trees. When a person scratches or rubs an irritated area, the skin can thinken there. The medical term for leather-like thickening of the skin is “lichenified.”

Nummular Eczema

Nummular eczema, or nummular dermatitis, causes round spots of dry, itchy skin that can eventually form sores. Thanks to its circular, raised patches, the scientists who defined the condition named it after another flat, round object: a coin. Given the Latin word for “coin” is “nummum” and the Greek word for the same is “nummus,” “nummular” became the offshoot term for the skin condition.

Seborrheic Eczema

The word “seborrheic” refers to sebum — the scientific term for the oil your skin produces. Sebum is made by the sebaceous glands in your skin, and the oil acts as a person’s natural skin and hair moisturizer. It also helps to protect your skin from bacterial infection and inflammation. However, certain microorganisms can overgrow in sebum, and when that happens, it can irritate a person’s skin and cause seborrheic dermatitis. Seborrheic dermatitis is most likely to occur in areas that contain lots of sebaceous glands, like your scalp, nose, chest, and upper back.

Stasis Dermatitis

Something is considered to be in a state of stasis if it is stopped or blocked. Stasis dermatitis happens when blood has a hard time traveling back up to the heart. This interrupted flow led to the condition’s name, which is also known as gravitational dermatitis or venous dermatitis (“venous” referring to the veins that can be involved).

In people with stasis dermatitis, a backlog of sluggish blood causes some of their small blood vessels (capillaries) to burst. Blood then leaks into their skin and causes it to become inflamed. Stasis dermatitis often occurs in the lower legs — the same place fluid retention often happens and causes edema.

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