Hematoxylin-eosin–stained sections revealed mucosal acanthosis and parakeratosis, with small foci of scale crust. There were clusters of cells within the epidermis that were filled with basophilic material, which was confirmed to be mucin deposition on alcian blue staining. Within the dermis, there was a dense lichenoid and diffuse inflammatory infiltrate composed of lymphocytes, histiocytes, plasma cells, and numerous eosinophils, with exocytosis into the overlying mucosa. No granulomas were identified. Stains, including periodic acid–Schiff, Steiner, and Warthin-Starry, were negative for microorganisms.
Crusted Swollen Lower Lip—Diagnosis. Arch Dermatol. 2006;142(12):1643-1648. doi:10.1001/archderm.142.12.1644-b