Kyphosis due to Osteoporosis: This is the most likely diagnosis given the age of the patient. Osteoporosis is common in elderly individuals and can lead to vertebral compression fractures, resulting in a hump on the back, also known as a kyphotic deformity.

Scheuermann's Kyphosis: Although more common in adolescents, Scheuermann's kyphosis can persist into adulthood and cause a noticeable hump on the back.
Degenerative Disc Disease: Wear and tear on the spinal discs can lead to a loss of height and curvature of the spine, resulting in a hump.
Spinal Stenosis: Narrowing of the spinal canal can cause pain and lead to a hunched posture, which may appear as a hump on the back.

Malignancy (e.g., Multiple Myeloma): Although less likely, it is crucial to consider malignancies that can cause vertebral destruction and subsequent kyphosis. Missing this diagnosis could be fatal.
Infection (e.g., Osteomyelitis, Discitis): Spinal infections can cause destruction of the vertebral bodies and discs, leading to a hump on the back. Prompt diagnosis and treatment are essential to prevent serious complications.
Spinal Fracture: A traumatic or pathologic fracture of the spine can result in a sudden onset of kyphosis and must be considered, especially if there is a history of trauma or cancer.

Achondroplasia: A genetic disorder that affects bone growth, leading to short stature and spinal deformities, including kyphosis. However, this would typically be diagnosed at a younger age.
Ehlers-Danlos Syndrome: A group of genetic disorders that affect connective tissue, which can lead to spinal deformities, including kyphosis.
Neurofibromatosis: A genetic disorder that can cause spinal deformities, including kyphosis, due to the growth of tumors on the spine.