Herpes Simplex Virus (HSV) Infection: Given the age and the presentation of a sore on the genitals, HSV infection is a common cause of genital ulcers in adults. The virus can reactivate over time, leading to recurrent episodes.

Syphilis: This sexually transmitted infection can cause a variety of genital lesions, including ulcers (chancre in primary syphilis) and rashes. It's essential to consider syphilis due to its increasing incidence and potential for serious complications if left untreated.
Genital Warts (Human Papillomavirus - HPV): While often associated with younger individuals, HPV can cause lesions in older adults, especially if they have had recent exposure or if their immune system is compromised.
Balanitis: An inflammation of the glans penis, often caused by poor hygiene, infections (bacterial, fungal), or irritants. It's more common in uncircumcised men and can present with soreness and lesions.

Squamous Cell Carcinoma: Although less common, any new or changing lesion on the genitals, especially in older adults, warrants consideration of skin cancer. Early detection is crucial for effective treatment.
Lymphogranuloma Venereum (LGV): A sexually transmitted infection caused by certain strains of Chlamydia trachomatis. It can lead to serious complications, including proctitis and lymphadenopathy, if not promptly treated.

Behçet's Disease: A rare condition characterized by recurrent oral and genital ulcers, along with other systemic symptoms. It's essential to consider in patients with recurrent or atypical ulcers.
Granuloma Inguinale (Donovanosis): A bacterial infection caused by Klebsiella granulomatis, leading to genital ulcers. It's rare in many parts of the world but should be considered in patients with a history of travel to endemic areas or in those who have not responded to standard treatments for other causes of genital ulcers.