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