Tinea Corporis and Juvenile Xanthogranuloma

Case 1:

A 20-year-old woman presents with a 3-week history of a pruritic, progressivelyenlarging erythematous lesion on one arm. She has a cat and recentlystarted horseback riding lessons. She is otherwise healthy and takes nomedication.Which of the following is the most likely cause of the lesion?

A.

Granuloma annulare.

B.

Bacterial cellulitis.

C.

Brown recluse spider bite.

D.

Tinea corporis.

E.

Panniculitis.What is the most appropriate diagnostic option?

F.

Bacterial culture.

G.

Fungal culture.

H.

Biopsy.

I.

Complete blood cell count and liver function tests.

J.

Potassium hydroxide (KOH) examination.

Case 1:

A

KOH examination, J,

confirmed the diagnosis of

tineacorporis, D,

that was most likelyacquired from horseback riding.Zoophilic organisms are more likelythan geophilic organisms toproduce inflammatory, pruritic reactions.Granuloma annulare isasymptomatic. Bacterial cellulitis,brown recluse spider bite, and panniculitisare painful rather thanpruritic.The patient responded quicklyto antifungal therapy. A veterinarianwas consulted about the horse.

Case 2:

The mother of a 2-year-old boyreports that he has had an asymptomaticyellowish nodule on hisnose for the past 8 months. He isotherwise healthy and has no historyof injury.

Which of the following do yoususpect?
A. Intradermal nevus.
B. Fibrous papule of the nose.
C. Spitz nevus.
D. Juvenile xanthogranuloma.
E. Urticaria pigmentosa.

Case 2:

A biopsy confirmed the diagnosis of

juvenilexanthogranuloma, D.

This lesion, which is typicallysolitary, usually erupts in the first year of life; it is mostcommonly seen in white boys. Most lesions spontaneouslyinvolute within 5 years. If multiple lesions occurbefore the age of 2 years, an ocular examination iswarranted, because 0.4% of patients will have intraocularlesions.Intradermal nevi usually do not have a yellowishtinge, and fibrous papules of the nose are not seenin this age group. Spitz nevi may resemble juvenilexanthogranuloma; the diagnosis is established on biopsy.Urticaria pigmentosa lesions become hive-like whenthey are stroked.

Case 3:

For 5 weeks, a 65-year-old womanhas had an asymptomatic, erythematous,slightly elevated papule onher right temple. There is no historyof trauma. She takes several medicationsfor mild hypertension andosteoporosis, but no new medicationshave been added in the past 6months.

What does this lesion look liketo you?
A. Actinic keratosis.
B. Lichenoid keratosis.
C. Seborrheic keratosis.
D. Fixed drug eruption.
E. Basal cell carcinoma.

Case 3:

The patient had a

lichenoid keratosis, B.

Thislesion has features of an actinic keratosis with a lymphocyticinfiltrate. A biopsy is sometimes necessary todistinguish lichenoid keratosis from other lesions.Typically seen after midlife on sun-exposed areas, theselesions are treated with cryosurgery.Actinic keratoses and basal cell carcinomas do nottypically enlarge so quickly; seborrheic keratoses are notusually inflamed. The patient's history did not implicatedrugs (although over-the-counter products can causeeruptions and should be included in the differential).