Atopic Dermatitis - Case Study.

This  7-month-old male child  is brought to clinic for a “rash all over.” Six weeks ago, his parents noticed him rubbing his legs against his crib and scratching his head frequently. They are concerned because they find blood on his sheets in the morning, and he has become increasingly irritable. He is eating and drinking normally.
His past medical history is unremarkable.
His father has sensitive skin and hay fever, but no one else in the family currently has a rash. He does not attend a daycare.
On skin exam, you find lichenified and erythematous patches of skin with fissures and bleeding on the ventral heels, dorsal feet, hands, and a few areas on the scalp. His cheeks are bright red with scale. His diaper area is uninvolved and there are no lesions in the web spaces of the hands and feet.

Q 1. Based on the description, which of the following is the most likely diagnosis?
A) Seborrheic dermatitis.
B) Atopic dermatitis (AD).
C) Scabies.
D) Tinea corpora.
E) Tinea versicolor.

Answer And Discussion

The correct answer is “B.” Atopic dermatitis (AD).

The most likely diagnosis is AD, also known by the moniker eczema. AD is characterized by dryness of the skin that is intensely pruritic. A red rash subsequently develops. AD is often referred to as the “itch that rashes.” It occurs in characteristic locations. In younger infants, the cheeks and neck are involved. As they begin to crawl, their extensor surfaces are involved. The diaper area, because it is moist, is not usually involved. In older children, the flexural areas, such as the antecubital and popliteal fossae, are involved.

Seborrheic dermatitis (“A”) is common in infants and usually is seen on the scalp and face, although it can involve the whole body. Seborrheic dermatitis is typically not hyperkeratotic and is less erythematous than AD.

Scabies (“C”) rarely involves the scalp, but it can do so in infants and the immunocompromised. However, other more typical locations (web spaces, wrists, waist, etc.) should be involved in scabies. Also, he does not appear to have any exposure to scabies.

Tinea corpora (“D”) is not usually widespread or brightly erythematous. Often, tinea corpora presents with a ring of advancing erythema and a central clearing (“ringworm”).

Finally, tinea versicolor (“E”) typically involves the trunk and extremities, not the scalp, and is not very pruritic.

You diagnose the patient with Atopic Dermatitis (AD)

Q 2. Which of the following is NOT true about AD?
A) The prevalence of AD appears to be increasing worldwide.
B) AD tends to worsen in the winter months.
C) In some patients, food allergies can exacerbate AD.
D) Positive skin prick tests and RAST testing correlate highly with food challenges (e.g., those with positive tests will have worsening of their rash when given a food challenge).
E) In most infants, AD will significantly improve or resolve by school age.

Answer And Discussion
The correct answer is “D.”

Sixty percent of AD appears in the first year of life, usually after 2 months of age. The cause of AD is not yet known. The role of specific allergens is controversial. In some patients, a food allergy can worsen the disease but is not thought to be the cause. However, in severe, unresponsive AD, food allergens should be evaluated. Most patients who have positive allergy testing to foods do not have improvement in their skin with removal of the allergen. Therefore, “D” is an incorrect statement. AD does tend to improve as the affected child ages.

Q 3. The hallmark of AD is:
A) Lichenification of the skin.
B) Pruritus and relapsing nature.
C) Associated asthma or allergic rhinitis.
D) Elevated IgE serum levels.
E) Redness of the skin with honey crusting.

Answer And Discussion
The correct answer is “B.” Pruritus and relapsing nature

Although all of the above can be associated with AD, waxing and waning pruritus is what defines this common skin condition. Chronic scratching often leads to thickened skin with accentuation of skin lines (lichenification). Early lesions will not have lichenification, however. Asthma and allergic rhinitis can be associated with AD. This common hypersensitivity triad is referred to as atopy (although AD is not allergic in nature).
“D,” elevated IgE, does occur in patients with AD, and higher levels of serum IgE are associated with more extensive disease of greater chronicity. However, an elevated IgE level is merely an association and is not pathognomonic of AD.
“E” is not diagnostic of AD. Erythema of the skin is a nonspecific sign of inflammation
and is seen in many skin disorders. Honey crusting implies a secondary bacterial infection (impetigo), which is common in AD but does not define the disease.

Q 4. Your initial recommendation should include the mainstay of long-term management of AD, which is:
A) Daily use of thick emollients such as white petrolatum.
B) Decreasing the bathing frequency to twice per week.
C) Topical corticosteroids or topical immunomodulators.
D) Oral antihistamines.
E) Oral antibiotics.

Answer And Discussion
The correct answer is “A.”

The protective barrier of the skin is broken down in patients with AD. By adding a protective barrier, such as petrolatum, frequently, the skin becomes less pruritic resulting in less itching induced skin trauma and rash, thus decreasing the “itch-scratch cycle.” This is the most important aspect of long-term management. Topical steroids and immunomodulators work well to decrease the inflammation
in the skin and are first-line anti-inflammatory treatment; however, the goal is to protect the skin with thick emollients so that the skin does not dry out and itch, leading to scratching and subsequent inflammation. Daily bathing with mild cleansers and cool water followed by the application of emollients, is recommended. Patients with AD have a higher bacterial count of Staphylococcus aureus on their skin. By bathing for short periods daily, the bacterial count is decreased thus decreasing the risk of secondary infection. Oral antihistamines cause some level of sedation, which is often helpful at night when the child is awake and itching. Interestingly, there is almost no evidence
to support the use of antihistamines in the treatment of AD, except small studies that have shown nonsedating antihistamines to be no better than placebo. If you choose to recommend an antihistamine, use an older drug (e.g., diphenhydramine).
 “E” is incorrect. However, oral antibiotics may be necessary if there is extensive impetigo. Finally, bacteria can lead to a flare of atopic dermatitis. Occasionally, treatment with antibiotics may be of benefit.

A recent ear infection has caused your patient’s skin to worsen. He returns to clinic and your physical exam reveals the skin lesion seen in the picture at the beginning of the case. . He has appreciably enlarged cervical lymph nodes. The patient has no known drug allergies.

Q 5. Which of the following oral antibiotics would be the best initial choice while you wait for culture and antimicrobial sensitivities?
A) Ciprofloxacin.
B) Trimethoprim/sulfamethoxazole.
C) Amoxicillin/clavulanic acid.
D) Tetracycline.
E) Metronidazole.

Answer and Discussion
The correct answer is “B.”

Patients with AD are prone to certain skin infections that may exacerbate their disease. Ninety percent of patients with AD will grow S. aureus on swab cultures of their crusted lesions. By decreasing the bacterial count, inflamed lesions often heal faster. With the rapid spread of community acquired methicillin-resistant S. aureus (CA-MRSA), it is safe to assume that many, or in some communities most, skin infections are due to CA-MRSA. Therefore, trimethoprim/sulfamethoxazole (Bactrim or Septra) is the most appropriate choice.
Tetracyclineis another option. However, this should be avoided in young children, as should fluoroquinolones (except in rare cases such as cystic fibrosis). Although not an option, cephalexin, a first-generation cephalosporin, would also be a reasonable initial choice as it has good skin penetration with good coverage of gram-positive cocci. However, neither cephalexin nor amoxicillin/
clavulanate will cover CA-MRSA.

Q 6. Which of the following vaccinations is contraindicated in patients with AD?
A) Smallpox (Vaccinia).
B) Varicella.
C) Measles/Mumps/Rubella.
D) Hepatitis B.
E) Pneumococcus.

Answer And Discussion
The correct answer is “A.”

 Vaccination against smallpox (Vaccinia), a live virus vaccine, is contraindicated in people with AD even when the condition is in remission. Vaccination may result in eczema vaccinatum, a severe and potentially fatal reaction.
Vaccinia vaccine is also contraindicated in all household contacts (e.g., parents of children with AD).
A family history of AD is not a contraindication.
Patients with eczema may also develop eczema herpeticum, a particularly severe form of disseminated herpes simplex with generalized sever ulcerations. These patients should be treated immediately with antivirals as the disease may be fatal.