Central odontogenic fibroma with amyloid: a diagnostically challenging case.

Odontogenic fibroma is a rare benign mesenchymal odontogenic tumor, with its histological diversity possibly posing diagnostic challenges. A case of the amyloid variant of central odontogenic fibroma, with epithelial cells in perineural and intraneural locations, is reported herein. The 46-year-old female patient had experienced discomfort related to her anterior right hard palate for approximately 25 years. Clinical examination revealed a depression in the anterior hard palate, and radiographic examination showed a well-defined radiolucent lesion with root resorption of the adjacent teeth. Histologically, the well-circumscribed tumor was composed of hypocellular collagenous connective tissue with small islands of odontogenic epithelium. In addition, the juxta-epithelial deposition of amyloid globules without calcification and epithelial cells in perineural and intraneural locations were observed, which posed a diagnostic challenge in differentiating the lesion from the non-calcifying variant of calcifying epithelial odontogenic tumor and sclerosing odontogenic carcinoma. However, on the basis of the clinical and radiographic findings, which were suggestive of a benign and slowly progressive process given the corticated, unilocular radiolucency, the considerable root resorption, and the long history of this finding in an otherwise healthy patient, the final diagnosis was amyloid variant of central odontogenic fibroma. Increased recognition of this variant of odontogenic fibroma and its differentiation from other more aggressive lesions could help the clinician to avoid overdiagnosis and overtreatment.

A cytochemical study of lactic dehydrogenase (LDH) isoenzymes in human lung cancer.

The cytochemical and electrophoretic LDH isoenzyme patterns in cells from lung cancer tissues were examined with 2.6 M urea treatment and the correlation between the LDH isoenzyme pattern and histopathological entities of lung cancer was also studied. The zymograms of the nonlesional lung tissues indicated the main peak at LDH3, with the M/H ratio 0.74. In tumor tissues, epidermoid carcinoma, adenocarcinoma, and large cell carcinoma showed almost similar patterns of isoenzymes with LDH4 peak. Though small cell carcinomas had a peak at LDH3, they indicated lower activity of %LDH1 and %LDH2 than those in nonlesional lung tissues. Most of the tumor tissues showed a high M/H ratio, more than 1.0. In cytochemical stain for LDH, no inhibitory effect of urea treatment was seen in the nonlesional lung tissues. On the other hand, in the cells obtained from three types of lung cancer, except for small cell carcinoma, urea inhibition was noticed. Cytochemical stainability for LDH-M subunits corresponded well to the results of LDH zymogram. These results suggest that the LDH stain with urea treatment is a useful method for detecting malignancy in cytological specimens.