A 55-year-old male presents to his GP with bilateral breast tenderness and swelling over six months. He denies nipple discharge or other systemic symptoms. Past medical history is unremarkable, and he takes no regular medications. Physical examination reveals the findings shown in the image. Vital signs are normal. Initial investigations including liver function tests, renal function tests, thyroid function tests, LH, FSH, prolactin, and testosterone are all within normal limits. Considering the clinical presentation, image findings, and normal initial investigations, which of the following is the most appropriate next step in the evaluation of this patient?