Meralgia Paresthetica: This condition is characterized by numbness, tingling, and burning pain in the outer part of the thigh due to compression of the lateral femoral cutaneous nerve. It is a common cause of anterior lower thigh numbness, especially in individuals who wear tight clothing or have recently gained weight.

Lumbar Radiculopathy (L2-L3): Nerve root compression or irritation in the lumbar spine can cause numbness in the anterior thigh. This is due to the involvement of nerve roots that contribute to the femoral nerve, which supplies sensation to the anterior thigh.
Femoral Neuropathy: Direct injury or compression of the femoral nerve can lead to numbness in the anterior thigh, along with potential weakness of the quadriceps muscle.
Diabetic Neuropathy: Diabetes can cause peripheral neuropathy, which may manifest as numbness in various parts of the body, including the anterior lower thigh.

Spinal Cord Compression: Conditions like spinal stenosis, tumors, or abscesses can compress the spinal cord, leading to numbness, weakness, and potentially severe neurological deficits. Early diagnosis is crucial to prevent irreversible damage.
Abdominal Aortic Aneurysm: Although less common, a large abdominal aortic aneurysm can compress adjacent nerves, including those supplying the lower extremities, leading to numbness and other symptoms.

Neurosyphilis: A late manifestation of syphilis infection, neurosyphilis can cause a variety of neurological symptoms, including numbness in unusual patterns.
Vasculitis (e.g., Giant Cell Arteritis): Inflammation of blood vessels can lead to nerve ischemia and damage, resulting in numbness and other neurological symptoms.
Tumors (e.g., Schwannoma, Neurofibroma): Benign or malignant tumors affecting nerves can cause localized numbness and other neurological deficits.
Sarcoidosis: A systemic disease that can affect any part of the body, including the nervous system, leading to numbness and a wide range of other symptoms.