Differential Diagnosis for White Plaque-like Raised Lesion between Labia

Single Most Likely Diagnosis

• Lichen sclerosis: This condition is characterized by white, patchy, or plaque-like lesions that can occur on the vulva, including between the labia. It is more common in women and can be associated with autoimmune diseases, such as multiple sclerosis. The patient's history of RRMS and immunosuppressant use increases the likelihood of autoimmune-related conditions.

Other Likely Diagnoses

• Lichen planus: An autoimmune condition that can cause white, lacy, or plaque-like lesions on the vulva, including between the labia. It can be associated with other autoimmune diseases.
• Vulvar intraepithelial neoplasia (VIN): Although less likely given the description, VIN can present with white lesions and is a concern in immunosuppressed patients due to their increased risk of neoplastic changes.
• Candidiasis: A fungal infection that can cause white lesions, though these are typically more diffuse and accompanied by other symptoms like itching and burning.

Do Not Miss Diagnoses

• Squamous cell carcinoma: Although rare, any persistent or changing lesion in an immunosuppressed patient warrants concern for malignancy. Early detection is crucial for treatment outcomes.
• Extramammary Paget's disease: A rare malignancy that can present with vulvar lesions, which might appear as white plaques. It's essential to consider this diagnosis due to its potential for malignancy.

Rare Diagnoses

• Vulvar leukoplakia: A rare condition characterized by one or more white patches or plaques on the vulva, which can be associated with an increased risk of cancer.
• Bowenoid papulosis: A rare sexually transmitted infection caused by high-risk HPV types, presenting with small, brown or white lesions on the vulva.

Each of these diagnoses should be considered in the context of the patient's medical history, including her immunosuppressed state due to multiple sclerosis treatment, and a thorough examination and diagnostic workup should be undertaken to determine the cause of the lesion.