Lumbar Radiculopathy (L2-L4): This condition is characterized by nerve root irritation or compression in the lumbar spine, which can cause numbness, tingling, and pain in the thigh. The symptoms can worsen with activities like walking and sitting due to increased pressure on the affected nerve roots.

Piriformis Syndrome: This condition involves the piriformis muscle compressing the sciatic nerve, leading to symptoms like numbness and tingling in the thigh. Activities that involve sitting or walking can exacerbate the symptoms.
Meralgia Paresthetica: This is a condition that involves compression of the lateral femoral cutaneous nerve, leading to numbness, tingling, and burning sensations in the outer part of the thigh. Prolonged standing, walking, or sitting can worsen the symptoms.
Peripheral Neuropathy: This condition involves damage to the peripheral nerves and can cause numbness, tingling, and pain in the affected areas, including the thighs. Diabetes, vitamin deficiencies, and alcohol abuse are common causes.

Spinal Stenosis: A narrowing of the spinal canal that can put pressure on the spinal cord and nerves, leading to pain, numbness, and tingling in the thighs. Symptoms can worsen with walking and standing.
Cauda Equina Syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to numbness, tingling, and potentially severe neurological deficits. It requires immediate medical attention.
Abdominal Aortic Aneurysm: Although less common, a large abdominal aortic aneurysm can compress adjacent nerves, leading to thigh symptoms. It's a medical emergency if ruptured.

Neurosyphilis: A complication of untreated syphilis that can affect the nervous system, leading to a variety of symptoms including numbness and tingling.
Vasculitis: Inflammation of the blood vessels that can affect nerve supply, leading to numbness and tingling sensations.
Tumors (e.g., Schwannoma, Neurofibroma): Rarely, tumors along the nerves can cause compression leading to numbness and tingling in the thighs.