How do UVA and UVB rays contribute to the process of oncogenesis in skin cells


Leonard works in the agriculture industry and raises beef cattle. At 60 years of age, he has spent most of his life working outdoors harvesting hay and tending to his herds. His wife was the first to notice a change in his skin. One day, after taking off his shirt, she noticed a significant change in the mole he had on his right shoulder. It not only was darker but was moist and appeared to have been bleeding at one point. Surrounding the mole, his skin was red. His wife remembered hearing stories of Leonard working on his father’s farm, spending long hours out in the hot sun even though his father had gone into the barn to work during the hottest part of the day. She insisted him go to the family physician to have it examined (Chapter 52, Learning Objectives 10 and 11).

  1. Leonard’s physician performed a biopsy on the lesion and told Leonard he suspected the growth may be malignant melanoma. What cells are affected in this form of skin cancer? How might his childhood exposures to the sun predispose him to this form of cancer?
  2. How do UVA and UVB rays contribute to the process of oncogenesis in skin cells?
  3. The mole on Leonard’s shoulder was a nevocellular nevus. What are the cellular composition and appearance of this type of mole before it underwent malignant change?


Melanoma is a type of skin cancer affecting the melanocytes, the cells responsible for
making melanin, the skin coloring pigment (Heistein & Acharya, 2020). The melanocytes are
found deep in the skin layer of the epidermis and protect the body against harmful UV rays.
Prolonged exposure to UV rays is a common predisposing factor for malignant melanoma
(Heistein & Acharya, 2020). Leonard spent most of his days out in the sun, working with his
father on the farm as a child. His childhood exposure to the sun may have resulted in skin
changes that would later manifest as melanoma.
Prolonged and unregulated exposure to UVB and UVA rays over time harms the skin’s
DNA integrity and affects cell and tissue homeostasis resulting in mutations and skin cancer.
Unprotected sun exposure leads to other skin changes, including wrinkling, atrophy, and other
pigmentary changes (Sample & He, 2018). UV radiation is implicated in oncogenesis by causing
inflammation and inducing similar pathways that lead to subsequent skin changes and mutations.
UV radiation exposure culminates in the release of oxygen-reactive species, leading to
inflammation and other oncogenic processes.
Human nevus cells comprise fibronectin, laminin, proteoglycans, and type IV collagen.
Benign melanocytic nevus or nevocellular nevus usually appear round, oval, well-circumscribed,
and pigmented (National Cancer Institute, 2018). However, over time, with excessive exposure
to the sun, these cells change color, size, and shape, with the skin surrounding them becoming
more dry or scaly. The skin may also become itchy, lumpy, and bleed or ooze pus (National
Cancer Institute, 2018). Leonrad’s wife was right to advise him to see the doctor because his
symptoms proved changes to his mole. Otherwise, rarely do these skin lesions become