In a 48-year-old male with an incidentally discovered 1.5 cm pituitary lesion, normal visual fields, mild hyperprolactinemia, and otherwise normal pituitary function, what is the preferred management?

{
  "question": "A [AGE]-year-old male was discovered to have a pituitary lesion when he underwent a CT scan of his head after trauma. A subsequent enhanced MRI scan showed a 1.5cm hypointense area in the anterior pituitary. No optic chiasm involvement or invasion of surrounding structures was noted. His serum TSH was 3.5mU/L. T3 and T4 were within normal limits. Serum prolactin was 590mU/L (45–375). IGF1 was 31nmol/L (14–47). After an overnight dexamethasone suppression test, his cortisol was 28nmol/L. His FSH was 6IU/L (1.4–18) and his LH was 7IU/L (3–8). Serum testosterone was 7nmol/L (8.4–28). He had a normal short synacthen test. His GH level was <2mU/L following a 75g glucose tolerance test. His visual fields were normal on formal testing. He feels well in himself and clinical examination was normal. After all of the above investigations he returns to clinic and inquires about the future management. Which of the following is true? A. There is more than a 75% chance that the lesion will regress with time B. Radiotherapy will be an essential part of management C. If untreated the most likely pituitary hormone deficiency to develop next would be thyroid deficiency D. His pituitary function is likely to return to normal if treated with trans-sphenoidal surgery E. Conservative management with close follow up is the preferred management option"
}