Vulvar dermatoses: a histopathologic review and classification of 183 cases.

BACKGROUND Vulvar dermatoses are often difficult to classify due to histopathologic overlap. We aimed to report our experience at a single institution. METHODS A total of 183 non-neoplastic, non-infectious vulvar biopsies were reviewed. Associations between histopathologic features and specific diagnoses were analyzed by Chi-squared tests. RESULTS Twenty-two biopsies (12.0%) showed two concurrent processes. A limited differential rather than a definitive diagnosis was rendered in 15 cases (8.2%). The final diagnoses included lichen sclerosus (LS) (38.8%), lichen simplex chronicus (LSC) (29.0%), eczematous dermatitis (23.0%), Zoon vulvitis (8.2%), non-specific/resolved dermatitis (5.5%), hidradenitis suppurativa (2.7%), Behçet disease (2.2%), lichen planus (1.6%), ruptured cyst (1.6%), ulcer not-otherwise-specified (1.6%), psoriasis (1.1%), radiation dermatitis (1.1%), sebopsoriasis (1.1%), seborrheic dermatitis (1.1%), epidermolytic hyperkeratosis (0.5%) and granular parakeratosis (0.5%). Early LS and Zoon vulvitis were commonly included as part of a differential diagnosis. LS was associated with wiry collagen with lymphocyte entrapment (p = 0.0188). LSC was associated with zones of pale epithelium (p = 0.0084), and often displayed prominent fibroblasts (p = 0.0555). Zoon vulvitis was frequently misdiagnosed, and was associated with basal keratinocytic crowding (p < 0.0001). CONCLUSIONS Our study has determined the relative frequencies of a wide variety of vulvar dermatoses, and identified new diagnostic clues for early LS, LSC and Zoon vulvitis.