Differential Diagnosis for a Lump on the Left Side of the Labia

Single Most Likely Diagnosis

• Bartholin's cyst: This is the most common cause of a lump in the labia, especially if it's localized to one side. Bartholin's glands are located on each side of the vaginal opening and can become blocked, leading to cyst formation.

Other Likely Diagnoses

• Lipoma: A benign tumor composed of fat tissue, which can occur anywhere on the body, including the labia.
• Folliculitis or abscess: An infection of the hair follicles or a collection of pus in the labial area, which can present as a lump.
• Sebaceous cyst: A benign, usually painless, bump under the skin that can occur in the labial area.
• Vulvar varicosities: Enlarged veins in the vulvar area, which can cause lumps or swelling, especially during pregnancy.

Do Not Miss Diagnoses

• Squamous cell carcinoma or other vulvar cancers: Although rare, any new or changing lump in the genital area warrants consideration of malignancy to ensure early detection and treatment.
• Genital herpes: Can cause painful lumps or sores, and while not typically described as a single lump, it's crucial to consider due to its infectious nature and potential for complications.
• Lymphogranuloma venereum (LGV): A sexually transmitted infection that can cause lymphadenopathy (swollen lymph nodes) in the groin area, which might be mistaken for a labial lump.

Rare Diagnoses

• Vulvar leiomyoma: A rare, benign tumor of smooth muscle that can occur in the vulva.
• Dermoid cyst: A rare type of cyst that can occur in the vulvar area, containing skin and sometimes hair, teeth, or other tissue.
• Vulvar hidradenoma: A rare, benign tumor originating from sweat glands in the vulvar area.

Each of these diagnoses has a different set of implications for treatment and management, emphasizing the importance of a thorough evaluation to determine the cause of the lump.