Metastatic Prostate Cancer with Spinal Cord Compression: Given the patient's history of elevated PSA and recent urology visit, the concern for prostate cancer is high. The symptoms of leg weakness, tingling, and calf swelling could indicate spinal cord compression, a known complication of metastatic prostate cancer.

Deep Vein Thrombosis (DVT): The patient's symptoms of calf swelling and leg cramps could be indicative of a DVT, which is a common condition in older adults.
Peripheral Artery Disease (PAD): The patient's leg cramps and weakness could also be symptoms of PAD, which is a condition characterized by narrowing of the peripheral arteries.
Lumbar Disc Herniation: The patient's symptoms of leg weakness and tingling could be indicative of a lumbar disc herniation, which can compress nerves and cause neurological symptoms.

Spinal Epidural Abscess: Although less likely, a spinal epidural abscess is a potentially life-threatening condition that can cause neurological symptoms similar to those experienced by the patient. It is essential to consider this diagnosis to avoid missing a potentially deadly condition.
Cauda Equina Syndrome: This is a rare but serious condition that occurs when the nerves in the spinal canal are compressed, causing neurological symptoms such as leg weakness, numbness, and tingling.
Aortic Aneurysm: Although not directly related to the patient's neurological symptoms, an aortic aneurysm can cause leg weakness and swelling due to compression or embolism.

Neurosyphilis: This is a rare condition that can cause neurological symptoms such as leg weakness and tingling, but it is less likely given the patient's presentation and history.
Lymphoma: Although lymphoma can cause spinal cord compression and neurological symptoms, it is a less likely diagnosis given the patient's history of elevated PSA and recent urology visit.