Abstract
Three cases out of 65 pleomorphic adenomas (4.6%) in our clinic were characterized by cystic regions. The present report, comprises a histological study of these cases of pleomorphic adenoma with cystic structures histologically.
Case 1: The pathological diagnosis was a pleomorphic adenoma with cystic structures in the submandibular gland. Macroscopically, the cyst had a very thin wall and contained a clear brown liquid. The inner surface of the cyst was not smooth and was lined by one layer of squamous cell without mucus- producing cells. The adjacent area of the cyst and the surface projecting into the cyst were composed of a myxoid area and sheets of small cubic or spindle-shaped tumor cells. The cyst contained eosinophilic mucin. The histogenesis of this cyst was speculated to occur as follows: eosinophilic mucin was probably secreted by cells of epithelial origin; the mucin was retained and extended into the myxoid area to form a large cyst.
Case 2: The pathological diagnosis was a pleomorphic adenoma with cystic structure in the parotid gland. The cyst was filled with a gel-like material. The inner surface of the cystic lumen was lined with stratified squamous cells. Since eosinophilic material in the cyst was keratinized forming epithelial plugs in this case, we speculated that this cyst was similar to the so called epidermoid cysts.
Case 3: The pathological diagnosis of this case was the same as that of case 2. The cyst was filled with a clear brown liquid. Histologically, the major part of the tumor was composed of a myxoid area. The cyst-like structure was localized within this myxoid area. In this case, we speculated that the cyst was formed by a degenerative change in the myxoid area.
