The American Society of Dermatopathology

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Interactive Case Study - July 2020

86-year-old woman with a reticular rash

Aimi Toyama, MD; Erick S. Jacobson-Dunlop, MD; Robert W. Werling, MD

Question 1:

An 86-year-old woman with a raised, reticular, pruritic rash on the left lateral shoulder of 2-3 months duration (Figure 1), estimated to have started after hospitalization for myocardial infarction.  Medical history includes left shoulder osteoarthritis, untreated torn left rotator cuff, and left-sided breast carcinoma treated with lumpectomy 30 years prior.  A punch biopsy of the area showed the following histopathology (Figure 2a-2c).  The cytokeratin AE1/AE3 stain is also shown (Figure 3a, 3b).  

Figure 1.

Figure 2a.

Figure 2b.

Figure 2c.

Figure 3a.

Figure 3b.

What is the most likely diagnosis?