Differential Diagnosis for Itchy Pimple on Labia

Single Most Likely Diagnosis

• Folliculitis: This is an inflammation of the hair follicles, which can cause itchy pimples. Given the location on the labia, where hair follicles are present, and the symptoms described, folliculitis is a common and plausible diagnosis.

Other Likely Diagnoses

• Contact Dermatitis: An allergic reaction or irritation from soaps, dyes, or other products can cause itchy lesions on the labia.
• Genital Herpes: Although typically associated with painful blisters, some cases can present with itchy lesions, especially during the initial outbreak.
• Molluscum Contagiosum: A viral infection that causes small, pearly, or flesh-colored bumps, which can be itchy and are contagious.

Do Not Miss Diagnoses

• Squamous Cell Carcinoma: Although rare, any persistent or changing lesion on the genital area should be evaluated for the possibility of skin cancer.
• Syphilis: The primary stage of syphilis can present with a single, painless chancre, which might be perceived as an itchy pimple if it becomes secondarily infected.
• Genital Warts (HPV): Caused by the human papillomavirus, these can appear as small, flat, or raised growths and can be itchy.

Rare Diagnoses

• Hidradenitis Suppurativa: A chronic skin condition that can cause painful, itchy bumps in areas where skin rubs together, including the groin area.
• Keratoacanthoma: A rare, low-grade malignancy that can resemble a pimple but grows rapidly and can be itchy.
• Lichen Sclerosus: A condition that creates patchy, white skin that's thinner than normal, which can be itchy and painful, often affecting the genital and anal areas.

Each of these diagnoses has distinct characteristics, and a thorough medical evaluation, including history, physical examination, and possibly diagnostic tests, is necessary to determine the correct diagnosis and appropriate treatment.