Question

A 62-year-old male has a reddish, rough

patch with white scales on the top of his ear.
He does not get this treated, and 3 years later
it has become an enlarged, raised lesion with
a central
ulcerated area that will not heal. Of
the following, which is the most likely causative
factor for this malignancy?
(A) Creation of pyrimidine dimers
(B) Creation of hydroxyl radicals
(C) Oncogenic RNA virus
(D) TNF receptor mutation
(E) Double-strand breaks in the DNA

Answer 1

The most likely causative factor for the described malignancy is the creation of pyrimidine dimers due to UV radiation exposure.

Step-by-step explanation:

The most likely causative factor for the malignancy described in the question is creation of pyrimidine dimers.

In this case, the individual's initial symptom of a reddish, rough patch with white scales on his ear likely indicates the presence of actinic keratosis, a precancerous lesion caused by UV radiation exposure. Without treatment, actinic keratosis can progress to squamous cell carcinoma, the second most common type of skin cancer. The progression involves the creation of pyrimidine dimers in the DNA, which are abnormal covalent bonds between adjacent pyrimidine bases due to UV damage. These dimers disrupt normal DNA replication and repair processes, eventually leading to the development of a malignant lesion.