A Young Physician's Guide to Diagnosing Atopic Dermatitis

In this Sunday session on atopic dermatitis practice pearls, Raj Chovatiya, MD, PhD, assistant professor, director for the Center for Eczema and Itch, Northwestern University Feinberg School of Medicine, Chicago, Illinois, dove right into the age-old question in the dermatology world: does atopic dermatitis (AD) =eczema?

His response: yes and no. While both terms are often interchangeable when used to describe this common, pruritic, inflammatory skin condition that is characterized by chronic and relapsing dermatitis, eczema is actually Greek for “boiling” and a description of vesicular/bullous lesions (in the most technical terms, not considered a disorder). Dermatitis, on the other hand, which entered the Oxford English Dictionary in 1876, was used at that time as diseases that included lichen agrius, porrigo larvalis, and Besnier’s prurigo.

The confusion in the 2 terms remains to this day. While many clinicians use the words as synonyms, others use eczema to describe a morphology that includes acute, subacute, and chronic lesions. In the scientific literature, there is a robust list of words and phrases used interchangeably with AD, such as atopic eczema, atopiform dermatitis, Besnier’s prurigo, childhood eczema, flexural eczema, lichen agrius, neurodermatitis, and others.

How do you diagnosis atopic dermatitis? To that, Chovatiya responded, “Depends who you ask.”

While the disease as defined in 1933 is used as the basis of most diagnostic criteria, there are nuances of differences from the classic definitions. The 1933 diagnostic guidelines, for example, include looking at a family history of the disease, determining if it was preceded by infantile eczema, the presence of gray and brownish skin, instability or easy irritability of vasomotor nerves, and patch tests with irritating contact substances. Criteria in 1980 determined, among other things, that a patient must have 3 or more of basic features such as pruritis, personal or family history of atopy (asthma allergic rhinitis, etc.), and chronic dermatitis, while, in 1994 criteria in the UK included a history of general dry skin, a personal history of asthma or hay fever, and involvement of the skin creases, such as folds of the elbows, behind the knees, etc. Today, most clinicians abide by the guidelines laid out by the American Academy of Dermatology in 2014, which include many of the features mentioned above, associated features, and exclusionary conditions (seborrheic dermatitis, psoriasis, erythroderma or other causes).

“AD is more heterogenous than we once thought,” observed Chovatiya. The morphology currently includes nummular dermatitis, prurigo nodules, lichenoid lesions and others, and the topography includes the head, neck, eyelids, genitals, buttocks, and other body parts.

When determining AD in a patient, Chovatiya advises, “think about the wide variety of AD lesions that are not scaly patches, such as prurigo nodules, follicular eczema and lichenoid papules.” He urges clinicians to also remember the wide distributions on the body, and to look beyond the “winter itch, noting incidence, chronicity, and persistence.

Finally, said Chovatiya, “Remember there are 7 different types of eczema, and a long differential diagnosis list. AD is not one size fits all.”

Reference

Chovatiya R. Early dermatology practice pearls: atopic dermatitis. 2022 Fall Clinical Dermatology Conference. October 23, 2022. Las Vegas, Nevada.