Can You Identify the Skin Disorders Pictured Here?

Case 1:

A 68-year-old man presents with long-standing erythematous, scaly pruritic patches on his arms and legs. The rash on his left upper arm had suddenly become painful and vesicular during the past few days. He denies joint pain and nail changes but mentions that he takes hot showers and scrubs with a washcloth.

What is your clinical impression?

A. Streptococcal impetigo.
B. Candidiasis.
C. Asteatotic eczema.
D. Herpes zoster.
E. Methicillin-resistant Staphylococcus aureus (MRSA) infection.
F. Psoriasis.

(Answer on next page.)

Case 1:

The clinical clues of grouped vesicles in a dermatomal distribution pointed to a diagnosis of

herpes zoster, D,

which was superimposed on the long-standing

asteatotic eczema, C,

that resulted from the patient's vigorous bathing habits. Impetigo and candidiasis were ruled out by the appearance of grouped vesicles. MRSA infection is typically painful, although in this patient's case, pruritus was the chief complaint. Psoriasis was ruled out by the lack of supporting findings (eg, thick, dry, silvery scales; joint pain; nail changes).

Case 2:

During a general skin examination, a lesion is noted on the chest of a 44-year-old man. The patient was completely unaware of this erythematous, scaly patch and is unable to provide any history. Your course of action is:

A. Wait and watch for the next 3 months.
B. Perform a potassium hydroxide examination.
C. Perform a skin biopsy.
D. Prescribe a topical corticosteroid.
E. Try a topical antibiotic for suspected impetigo.

(Answer on next page.)

Case 2: The friable, asymptomatic lesion raised the suspicion of cutaneous malignancy. A skin biopsy, C, confirmed the clinical impression of basal cell carcinoma.

Impetigo and ringworm are usually more symptomatic than the lesion seen here. Application of a topical corticosteroid would temporarily improve the appearance . . . and delay the diagnosis.

Case 3:

A 38-year-old man presents with a 20-year history of an asymptomatic red patch on his hip that suddenly started to spread during the past 2 weeks. He is unaware of possible precipitating events. He is otherwise healthy and takes no medications.

What might explain this rash?

A. Fixed drug eruption to over-the-counter medication.
B. Asteatotic eczema.
C. Tinea versicolor.
D. Tinea corporis.
E. Psoriasis.
F. Parapsoriasis.

(Answer on next page.)

Case 3: A biopsy confirmed the diagnosis of parapsoriasis, F. The small plaque variant (up to 5 cm) presents as well-demarcated patches, mostly on the trunk. The condition is usually asymptomatic and more common in men. Without treatment, the rash can persist for years. This patient's rash resolved with a short course of potent topical corticosteroids; after 2 years, there was no evidence of recurrence.

A fixed drug eruption is usually tender and inflamed. Asteatotic eczema, tinea corporis, and psoriasis are typically pruritic and scaly; tinea versicolor is typically scaly.

Case 4:

A 59-year-old man has a 2-year history of persistent pruritus on his right forearm. He does not think that sun exposure affects his condition, nor does wearing sunscreen seem to help. He takes a lipid-lowering agent and an aspirin daily. He owns a cat.

What does this look like to you?

A. Tinea corporis.
B. Asteatotic eczema.
C. Lichen simplex chronicus.
D. Psoriasis.
E. Cutaneous lupus erythematosus.
F. Polymorphous light eruption.

(Answer on next page.)

Case 4:

This patient has

lichen simplex chronicus, C,

a self-perpetuating neurodermatitis. The initiating event is often not identified, but the scratching perpetuates the cycle. A short period of occlusion may relieve the pruritus; topical corticosteroids are often ineffective. Topical doxepin or pramoxine may be helpful.

Tinea corporis would typically not persist for 2 years without spreading. Asteatoses are usually not confined to a single extremity. Psoriasis is generally bilateral and features more erythema and scale than this patient's rash. Cutaneous lupus erythematosus and polymorphous light eruption are aggravated by sun exposure and are more erythematous.

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