Ryoichi Yasui

Clear-cell variant of mucoepidermoid carcinoma: Report of a case with immunohistochemical and ultrastructural observations

Abstract Mucoepidermoid carcinoma, first described as a distinct entity by Stewart et al in 1945, 1 is relatively common among major and minor salivary gland malignancies. Histologically, this tumor is composed of mucus-secreting cells, epidermoid cells, and intermediate cells in varying proportions. In addition to these essential cell types, clear cells have also been described as an occasional component of the tumor parenchyma. 1–4 Less commonly, clear cells may predominate, which causes difficulty in diagnosis. 5,6 This article reports a rare case of this type of mucoepidermoid carcinoma arising from minor salivary glands of the retromolar region. Pertinent histochemical, immunohistochemical, and ultrastructural findings that can aid in the differentiation of this tumor from other clear cell neoplasms are discussed.

A new method of conserving the inferior alveolar nerve during resection of the mandible

A method is presented of conserving the inferior alveolar nerve where resection of the mandible is necessary. The technique features the delivery of the nerve through the mandibular foramen and the end-to-end anastomosis of the previously sectioned nerve. The technique is particularly indicated in the treatment of carefully chosen cases of benign and locally invasive neoplasms and cysts with complex cavities.

A multifocal schwannoma of the masseteric nerve causing hemicrania

A case is reported of schwannoma of the right masseteric nerve, invading the pterygopalatine fossa and the parapharyngeal space through the mandibular notch in a 61-year-old woman. The tumor in this case was composed of four various-sized interconnected nodules, simulating a string of beads. The tumor was the cause of the patients chronic hemicrania, as confirmed by the relief from and disappearance of head pain after surgical removal of the tumor. The most important aspects of this case are the anatomic site of the schwannoma and its uncommon clinicopathologic manifestations; this tumor originated from the masseteric nerve and is the first case reported to straddle the mandibular notch.

Large retention cyst of the accessory parotid gland associated with a mucoepidermoid tumor in the cyst wall

Abstract Mucous retention cysts rarely occur in the parotid gland, and a coexistent mucoepidermoid tumor in the cyst wall is even more unusual. This article reports such an uncommonly large cyst that probably arose from the accessory parotid gland. After histologic examination of the extirpated cyst wall, it was discovered that a localized part of the cyst wall was occupied by a mucoepidermoid tumor.