The American Society of Dermatopathology

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Interactive Case Study - March 2019

A 25-year-old male with a painful nodule in the perianal region

Noman Javed, MD; Laura A. Greene, MD

Question 1:

A 25-year-old male college student presents with an increasingly painful nodule in the right perianal area. A biopsy shows the following histopathology (Figures 1-4), histochemical (Figure 5), and immunohistochemical (Figure 6) staining.

Click this image to view the virtual slide

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Which of the following is the best diagnosis?