Page 157 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-72 Rashes

SEBORRHEIC DERMATITIS

Seborrheic dermatitis is a commonly encountered rash
with a bimodal age distribution. There is an infantile
and an adult form. The two forms do not resemble each
other clinically and are distinct in appearance. The
infantile form has also been named “cradle cap” because
of its prominent location on the scalp. The adult form
has been found in association with many underlying
conditions, although it is most commonly seen as an
isolated skin finding.
Clinical Findings: The infantile form of seborrheic
dermatitis manifests in the first weeks of life and lasts a
few months at most. It affects males and females equally,
and there is no racial predilection. The most usual loca-
tion of involvement is the scalp. Most cases are mild
and do not cause the parents to seek the advice of a
medical professional. These mild cases manifest with a
fine scale that may be slightly greasy or adherent. The
child is unaware of the dermatosis, and it resolves spon- In infants, seborrheic dermatitis
taneously. Rarely, an infant develops greasy yellow, is is referred to as “cradle cap”
scaly patches and even plaques across the entire scalp because of the development
(cradle cap). The dermatitis may become more inflamed, of greasy crusted patches on the
and weeping from the patches or plaques may ensue. scalp.This common finding
The infant may try to scratch at the areas, indicating in infancy typically improves
that pruritus is present. In these severe cases, weeping spontaneously over time.
patches and plaques may also be seen in the groin and
axillary folds. Only in the most exceptional of cases does
the rash disseminate, but it has the ability to affect any
region of the body.
The adult version is chronic in nature and affects a
higher percentage of people than does the infantile form.
Because of its chronicity, patients often seek medical
advice. There is also quite a bit of clinical variability in
adult seborrheic dermatitis. The face is the most com-
monly involved site, with a predilection for the nasola-
bial fold, eyebrows, ears, and scalp. It has a strikingly
similarity to patches in other locations on the skin. Most
cases are mild and consist of greasy yellow to slightly red,
scaly patches. The scalp involvement is similar in appear-
ance. Seborrheic dermatitis has a propensity to affect the
areas of the skin that have a high density of sebaceous
glands. On occasion, patients have not only facial
involvement but signs of involvement on areas of the
upper chest and back.
Many conditions have been associated with the adult
form of seborrheic dermatitis, including Parkinson’s
disease and other chronic neurological disorders. Adult
onset of severe seborrheic dermatitis has been reported Severe seborrheic dermatitis may be associated
to occur with a higher incidence in patients with under- with human immunodeficiency virus (HIV)
lying human immunodeficiency virus (HIV) infection. infection.
HIV-associated seborrheic dermatitis tends to be wide-
spread, with severe facial involvement. Patients who
present with severe seborrheic dermatitis should be Seborrheic dermatitis in adults frequently
assessed for HIV risk factors. manifests with greasy yellow, scaly patches
Pathogenesis: The exact pathogenesis is unknown. in the scalp, ears, and eyebrows and along
Seborrheic dermatitis is believed to be caused by an the nasolabial fold.
interaction of various components of the skin, includ-
ing the production of sebum, with the normal skin
immune system response to the fungus, Malassezia
furfur. The role that each of these factors plays in the Treatment: Most cases of infantile seborrheic derma- therapy. The other azole antifungal agents are just as
formation of seborrheic dermatitis is not completely titis can be ignored or treated with nothing more than effective. The addition of a weak topical corticosteroid
understood. daily baths and a bland emollient. More involved cases used intermittently can also lead to excellent results.
Histology: Seborrheic dermatitis is almost never can be treated with more frequent shampooing of the The scalp is most commonly treated with a ketoconazole-
biopsied to confirm the diagnosis. Classic biopsy spe- scalp and the use of a mild topical corticosteroid. The based shampoo or a tar- or selenium-based shampoo.
cimens show parakeratosis overlying a slightly spongi- use of ketoconazole cream has also been advocated in There is no cure for seborrheic dermatitis, but most
otic epidermis with a mild lymphocytic perivascular some cases. therapeutic regimens, if adhered to, lead to an excellent
infiltrate in the dermis. Spores of fungus can be seen Because of its chronic nature, adult seborrheic der- clinical response.
lying on the surface of the epidermis. matitis is treated with topical ketoconazole as a first-line

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 143