Degenerative Disc Disease or Lumbar Spinal Stenosis: This condition is a common cause of leg pain, especially in older adults, and can be associated with weight loss due to decreased mobility and appetite. The pain often radiates down the leg and can be exacerbated by walking or standing.

Peripheral Artery Disease (PAD): PAD can cause leg pain, especially when walking, and is associated with weight loss due to decreased mobility. Risk factors include smoking, diabetes, and hypertension.
Diabetes Mellitus with Neuropathy: Diabetes can cause leg pain due to neuropathy and is often associated with weight loss. Other symptoms may include numbness, tingling, and weakness in the legs.
Chronic Venous Insufficiency: This condition can cause leg pain, swelling, and skin changes, and may be associated with weight loss due to decreased mobility.

Osteosarcoma or Other Bone Cancers: Although rare, bone cancers can cause leg pain and weight loss. It is crucial to consider this diagnosis, especially in younger patients or those with a history of cancer.
Spinal Cord Compression or Cauda Equina Syndrome: These conditions are medical emergencies that can cause leg pain, weakness, and weight loss. Prompt diagnosis and treatment are essential to prevent permanent damage.
Infectious Diseases (e.g., Osteomyelitis, Septic Arthritis): Infectious diseases can cause leg pain, fever, and weight loss. It is essential to consider these diagnoses, especially in patients with a history of trauma, surgery, or immunocompromised states.

Ehlers-Danlos Syndrome: A genetic disorder that can cause leg pain, joint hypermobility, and weight loss due to gastrointestinal complications.
Fabry Disease: A rare genetic disorder that can cause leg pain, neuropathy, and weight loss due to gastrointestinal and cardiac complications.
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): A rare autoimmune disorder that can cause leg pain, weakness, and weight loss due to neuropathy.