Histology Course A IV 29 Department of Pathology, University of Zurich Histokurs

A IV 29

dermal nevus HE further information (German) on HiPaKu 
  ICD-10: D22; ICD-O: 8720/0
42-year-old male observed a small, dark, slowly growing nodule on his left forearm. Clinically, a malignant melanoma was suspected and the lesion excised (compare slides A II 8, A IV 30 )
- Well circumscribed, symmetrical lesion.
- Immediately beneath the epidermis dermal nests of nevus cells are found, some of which contain melanin pigment.
- Nevus cells display uniform, rounded nuclei with inconspicuous nucleoli and exhibit little or no mitotic activity.
- Nevus cells grow along skin appendages without destroying them. Nests of nevus cells are frequently found in association with hair follicles.
- In the depth of the lesion nevus cells show maturation: they are smaller, grow in cords and do not contain melanin.

Nevocellular nevi rarely progress into malignant melanomas.