Presence of a Mucin-phagocytic Reaction after Treatment of a Mucous Cyst with Local Triamcinolone Acetonide Injection

Abstract

We describe herein two cases of mucous cyst with infiltration of mucoprotein-containing histiocytes. One patient had a mucous cyst of the lower lip, and the other had a digital mucous cyst of the thumb. These patients were treated by surgical excision after local triamcinolone acetonide injections were administered. Histologic features of the surgical specimen from the mucous cyst of the lower lip showed solid regions of various sizes that were composed of cells with abundant granular basophilic cytoplasm, round nuclei were observed in the submucosa and muscle tissues. The surgical specimen from the digital mucous cyst also showed infiltration of the same type of cells in the upper dermis. The cells were positive with mucicarmine and Alcian blue at pH 2.5. Metachromasia was demonstrated by toluidine blue stain. Immunohistologically, CD68 and lysozyme stains were postitve in the majourity of the infiltrating cells. These histological findings show the pattern expected in mucoprotein-containing macrophages, and these cases suggest that local triamcinolone acetonide injection for mucous cyst may induce a mucoprotein-phagocytic reaction.