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congenital nevus

Friday 2 December 2022

PO

Synopsis

- Tends to involve reticular dermis, subcutis, skin adnexa, arrector pili muscles and nerves with single cell permeation of collagen
- Also neural differentiation with Wagner-Meissner-like corpuscles
- Frequent proliferative nodules
- Lesions of infants may have pagetoid melanocytic proliferation

- Proliferative nodules:

  • Dermal nodules of large epithelioid or spindled melanocytes that merge with surrounding nevus cells
  • Often prominent nucleoli, cellular areas, focal hemorrhage and ulceration but no necrosis, no destructive growth, minimal inflammation and 0 - 4 mitotic figures/10 HPF
  • Lesions mature and regress over time

Differential diagnosis

- glomus tumor
- malignant melanoma