Review of Answer Choices (Correct Answer in Green):
A. Sharply-marginated erythematous papules and patches with silvery-white scale.
B. Homogeneous erythrodermic pattern covering > 90% of the body surface with morbilliform eruption over the anterior abdomen.
C. Xerotic, fissured, and scaly plaques with lichenification and excoriation.
D. Superficial, well-defined edematous papules and plaques or “wheals”.
Explanation:
A. Sharply-marginated erythematous papules and plaques with silvery-white scale. This is the classic description of psoriasis. Erythema in individuals with darker skin often appears violaceous, which is indeed what we see here. However, the rash covers his entire body and is not well-marginated. In addition, there is no scaling currently present (though there may be in chronic forms of this condition), and there is no wide-spread raising of the skin (as in the case of plaques).
B. Homogeneous erythrodermic pattern covering >90% of the body surface with morbilliform eruption over the anterior abdomen. This is the correct answer. Mr. Magoro’s skin is homogeneously erythematous to violaceous over a very large portion of his total skin surface area. In addition, the morbilliform exanthema (also known as “maculopapular” for the combination of macules and papules present, mimicking viral exanthem from measles) present on his anterior abdomen may help provide a clue into the cause of the overall skin condition.
C. Xerotic, fissured, and scaly plaque with confluent erythema, crusting, lichenification, excoriation. This is the classic description of atopic dermatitis or “eczema.” Although the patient’s current skin condition can present with itchy, scaly, erythematous skin with lichenification due to itching and atopic dermatitis can be a trigger, the presenting condition’s morphology differs from isolated eczema. In addition, eczema is more commonly found on flexor surfaces of the body, whereas this present condition is found over almost the entire surface.
D. Superficial, well-defined edematous papules and plaques or “wheals”. This is the description of an urticarial rash, commonly present during an allergic reaction. Like Mr. Magoro’s rash, an urticarial rash can cover the entire surface of the body. In addition, the morbilliform abdominal rash seen may also present at the same time as an urticarial rash if due to a specific allergen. However, while an urticarial rash is well-defined and edematous, this patient’s skin condition is more homogeneous and poorly-demarcated without appreciable “wheals”.
Dermatologic conditions can be defined by a number of morphologic characterizations, including size, demarcation, degree of elevation/depression, presence of fluid/pus. The following table is a useful tool to help differentiate between some of the most-common dermatologic findings.
