Histopathological review of 667 cases of oral mucoceles with emphasis on uncommon histopathological variations.

Mucoceles can occur in the oral cavity, appendix, bladder, paranasal sinuses, and lacrimal sac. In the oral cavity, mucoceles arise from pathological alterations in the minor salivary gland ducts. In this study, we aimed to histologically reevaluate cases of oral mucoceles to identify possible variants. A total of 667 slides containing tissue sections stained with hematoxylin and eosin diagnosed as a phenomenon of mucus extravasation were analyzed under light microscopy by 4 previously trained examiners. In 128 cases (19.1%), 1 or more histopathological changes were identified. Twenty cases (2.9%) exhibited collagenous globular structures compatible with myxoglobulosis. In 30 cases (4.49%), dissociation of collagen fibers after mucin extravasation was observed. Fifty-four cases (8.09%) exhibited papillary synovial metaplasia-like change, and 32 (4.79%) showed a significant reduction in the lumen of the cavity due to large papillae. Twenty cases (2.9%) were compatible with superficial mucoceles, and in 11 cases (1.64%), the foamy macrophages showed an unusual solid arrangement, known as clear cell change. It is essential to recognize the possible histopathological changes in oral mucoceles to avoid diagnostic pitfalls.