How Seborrheic Dermatitis Is Diagnosed

Doctor Diagnosing Cradle Cap, a Form of Seborrheic Dermatitis

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Seborrheic dermatitis is a common skin condition. The rash of seborrheic dermatitis consists of scaly, greasy-appearing patches that form on oily parts of the skin, such as the scalp, face, and in the ear canals. It also manifests as cradle cap in infants and, in its milder form, as dandruff in adults. The diagnosis of seborrheic dermatitis is almost always made clinically, meaning by a doctor's trained eye and through a good history and skin examination. While the precise cause behind this skin disease remains unknown, experts suspect that a yeast species called Malassezia is involved.

Self-Checks

Before your appointment, make notes about your rash symptoms (or that of your child). Your doctor will ask you several questions about your rash, such as the location of your lesions ("spots or patches"), what makes your rash better or worse, if there are any associated symptoms like itching or burning, and if the rash is constant or comes and goes.

While you may be tempted to self-diagnose, this condition mimics several others. A primary care provider or dermatologist will be able to provide the best diagnosis and rule out other causes and recommend the correct treatment.

In adults, seborrheic dermatitis is often a chronic skin condition that comes and goes, often relapsing with specific triggers like stress or in cold, dry climates.

Labs and Tests

During your skin exam, in addition to examining the characteristics of your rash (e.g., presence of scaling), your doctor will make note of precisely where your rash is located.

With seborrheic dermatitis, the rash will be located only on certain parts of the body—those that contain a large amount of sebaceous or oil-producing glands, such as the scalp, center of the face, ears, eyebrows, upper chest and back, armpits, and genitals.

If the diagnosis of seborrheic dermatitis is still uncertain, a dermatologist may perform a skin biopsy. With a biopsy, a small area of the affected skin is removed and examined under a microscope.

Other tests may be performed if alternative diagnoses are being considered. For example, a KOH prep test may be done to rule out a fungal infection, which can mimic seborrheic dermatitis. Likewise, sometimes blood or other tests are ordered if your doctor suspects your seborrheic dermatitis is a sign of an underlying health conditon.

In the end, a good history and exam by your or your child's primary care doctor or dermatologist will not only help clinch the diagnosis of seborrheic dermatitis but also rule out alternative diagnoses.

Differential Diagnoses

There are several skin conditions that can resemble that of seborrheic dermatitis. This is why it's best to see a doctor for proper evaluation before engaging in any self-treatment.

To provide an example—one skin disease that may be easily confused for seborrheic dermatitis and yet requires a wholly unique treatment plan is psoriasis. Both psoriasis and seborrheic dermatitis cause a scaling skin rash, which may be present on the scalp. However, there are some key differences that a doctor can tease out during a skin exam.

The scales of psoriasis of silvery-white and often bleed when scratched off. On the other hand, the scales of seborrheic dermatitis are yellow-white in color, appear greasy and moist, and are usually fairly easy to remove. In addition, while both rashes can itch, psoriasis scales tend to feel more tender.

Besides psoriasis, other common skin conditions that may be confused for seborrheic dermatitis include:

A Word From Verywell

The diagnosis of seborrheic dermatitis is relatively straightforward and based on the appearance of the rash. Uncommonly, a biopsy may be utilized, mostly to rule out other skin conditions. The good news is that once diagnosed, you can move forward with a treatment plan that improves the appearance of the rash and eases any itching associated with it.

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Article Sources

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  1. Clark GW, Pope SM, Jaboori KA. Diagnosis and Treatment of Seborrheic Dermatitis. Am Fam Physician. 2015 Feb 1;91(3):185-90.


  2. Borda LJ, Wikramanayake TC. Seborrheic Dermatitis and Dandruff: A Comprehensive Review. J Clin Investig Dermatol. 2015 Dec;3(2). doi:10.13188/2373-1044.1000019


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