Case of superficial mucocele of the lower lip.

Superficial mucocele is a relatively rare bullous disease that develops in the oral mucosa. Although the number of reported cases is limited, it seems that the superficial mucocele has been recognized as an independent disease belonging to a single entity. We report a 48-year-old woman who repeatedly developed superficial mucocele in the oral mucosa. When she was admitted to our hospital she had a tense vesicle on her lower lip. A skin biopsy was taken from the vesicle. A blister containing neutrophils and erythrocytes was present in the mucous epithelium. There was a dermal infiltrate comprising neutrophils, mononuclear lymphocytic cells and eosinophils. Dilated salivary gland excretory ducts were seen in the lamina propria mucosae. Eosinophilic and amorphous materials, which were periodic acid-Schiff positive after digestion with diastase, and alcian blue positive, were deposited in the blister. Direct immunofluorescence was negative for immunoglobulin (Ig)G, IgM, IgA, C1q, C3 and C4. These histological findings led us to make a diagnosis of superficial mucoceles.