CLEAR CELLS TUMORS IN THE ORAL CAVITY: TWO CASES TO SHOW THE CHALLENGING DIAGNOSIS

Abstract

Introduction Clear cell carcinomas in the jaws are very infrequent neoplasms. Differential diagnosis includes metastatic carcinomas, mucoepidermoid carcinoma, clear cell odontogenic carcinoma, and others. We present two cases of jaw tumors and focus on the diagnostic challenge of each. Case Reports The first case is a 65 year-old man without diagnosis of a systemic disease, with a gingival red tumor and a radiolucent image with irregular borders in the incisor area. Histopathology showed proliferation of clear cells with round hyperchromatic nuclei, some with atypia. These cells formed solid nests separated by thin connective tissue septa with marked vascular proliferation. The clear cells presented diastase–periodic acid–Schiff, anti-Vimentin, anti-CD-10 and anti-PAX-8, anti-human Ki-67 positivity (30% of the cells) and it was negative for S-100 and CK-7. The diagnosis was clear cell carcinoma suggestive of clear cell metastatic carcinoma (MRCC). The second case is a 36 year-old woman with an asymptomatic radiolucent lesion in the periapical area of maxillary premolars. Histopathology showed a cellular proliferation formed by nests of clear oval and polygonal cells, with mild atypia separated by fibrous connective tissue septa. The immunohistochemical staining showed positivity for cytokeratin AE1/AE3 and negative for both S-100 and-smooth muscle actin. Mucicarmin and Congo-red stains were negative. This case was diagnosed as suggestive of clear cell odontogenic carcinoma (CCOC); it was indicated to rule out metastasis. The imaging evaluation confirmed a renal neoplasm in the first case and rule out the presence of lesions in the rest of the body in the second case. Conclusions CCOC and MRCC are histologically similar and immunohistochemistry studies play an important role in diagnosing clear cell tumors. So it is vital for the pathologist to know histomorphology and histo and immuno-histochemistry staining should be considered.