The American Society of Dermatopathology

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Interactive Case Study - April 2019

10-year-old with morbilliform rash

Kellen Dawson, MD; Michael DeWall, DO; Sara Shalin, MD, PhD

Question 1:

A 10-year-old Caucasian girl with a history of acute lymphoblastic leukemia, currently in remission but still on multiple chemotherapeutic drugs, presented with a new, worsening rash. Upon presentation, the rash had been present for five days and was described as erythematous, maculopapular and confluent macules coalescing into patches. The rash began on the chest and spread to the anterior neck, flexural arms, vulva, and perianal region; the back was spared. Other symptoms included a low grade fever, fatigue, and myalgias. Other pertinent clinical history included a recent history of strep throat and addition of dasatinib, which is a targeted kinase inhibitor, three days prior to onset of the rash. A punch biopsy was obtained.

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Figure 1. 4x

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Figure 3. 20x

Figure 4. 40x

What is the best diagnosis?