Question 1:
A 67-year-old man with history of immunoglobulin M (IgM) monoclonal gammopathy presented with a 2-centimeter, asymptomatic erythematous plaque with papules, prominent telangiectasias and a faint orange hue on the left posterior shoulder.
The lesion was biopsied, H&E and immunohistochemical (IHC) stains for CD3, CD20, CD138, PAX5, kappa, and lambda light chains were performed. The images are shown below. A CD5 stain, performed on a prior biopsy, highlighted only T lymphocytes.
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Figure 1. Clinical Lesion
Figure 2. H&E, 1x
Figure 3. H&E, 12x
Figure 4. H&E, 40x
Figure 5. CD3, 20x
Figure 6. CD20, 20x
Figure 7. CD138, 20x
Figure 8. PAX5, 20x
Figure 9. Kappa, 20x
Figure 10. Lambda, 20x
Figure 11. Congo red, 4x
What is the most likely diagnosis?