Genital Herpes: This is often the first consideration for painful genital lesions due to its high prevalence and characteristic presentation of painful vesicles or ulcers, typically accompanied by systemic symptoms like fever and malaise during the initial outbreak.

Syphilis: The primary stage of syphilis can present with a painful genital ulcer (chancre), although it's more commonly painless. The pain can be a distinguishing feature from other causes.
Bartholin Gland Abscess or Cyst: These can become infected and present as painful lesions on the labia, often accompanied by swelling and purulent discharge.
Folliculitis or Furuncles: Inflammation of the hair follicles (folliculitis) or a more severe infection forming an abscess (furuncle) can cause painful lesions in the genital area.

Squamous Cell Carcinoma: Although rare, any new or changing genital lesion, especially in older adults or those with risk factors (like HPV infection), should prompt consideration of malignancy to ensure early detection and treatment.
Lymphogranuloma Venereum (LGV): A sexually transmitted infection caused by certain strains of Chlamydia trachomatis, which can lead to painful lymphadenopathy and, if untreated, to more severe complications like genital elephantiasis.
Donovanosis (Granuloma Inguinale): A bacterial infection that causes chronic, progressive ulcerative lesions without pain, but can be painful if secondarily infected. It's rare in many parts of the world but can have significant morbidity if not treated.

Behçet's Disease: A form of vasculitis that can cause painful genital ulcers, among other symptoms like oral ulcers and ocular inflammation.
Crohn's Disease or Ulcerative Colitis: These inflammatory bowel diseases can rarely cause extraintestinal manifestations, including painful genital lesions or ulcers.
Fixed Drug Eruption: A skin condition that can cause painful lesions in response to certain medications, which can appear in the genital area among other places.