Mutational analysis of K-ras and Ras protein expression in larynx squamous cell carcinoma.

The ras gene family (H, K and N-ras) encodes the Ras protein, a GTPase-activating protein that regulates several signal transduction pathways including cellular proliferation and differentiation. Mutations in codons 12, 13 and 61 of the ras genes constitute one of the most frequent alterations in human cancer. In the Western Hemisphere, a low frequency of mutations in these genes has been observed in head and neck carcinomas; a higher frequency has been found in countries such as India and Taiwan. Increased protein expression is a relatively frequent event in larynx carcinomas. This study was aimed to evaluate the participation of the k-ras gene and Ras expression in 20 Mexican patients with larynx squamous carcinoma, 2 with dysplasia and 4 with normal mucosa. Samples (of 26 patients) were embedded in paraffin and immunohistochemical analysis was performed for the Ras protein, as well as amplification of the k-ras gene exon 1 (108 bp) by laser capture microdissection. Then, DNA extraction, PCR and sequencing were performed looking for possible mutation in codons 12 and 13. All patients with larynx carcinoma were men, median age 62 years. Eighty-five percent of the patients had risk factors such as smoking and/or alcohol consumption, 25% were in clinical stages I and II, and 75% in stages III and IV; 45% of the patients presented tumor recurrence or persistence. In this study, no mutations were found in codons 12 or 13 of the k-ras gene; however, protein expression was observed in 95% of the samples and a higher expression of the protein was associated with tumor recurrence or persistence, although this was not statistically significant. Unexpectedly, well-differentiated carcinomas and dysplasias presented an increase in protein expression. These results suggest that ras may be involved in early stages of larynx carcinogenesis and may be activated by other mechanisms different from mutations, such as epigenetic events.

Unusual salivary glands adenocarcinomas: a retrospective study.

Malignant tumors of the salivary gland ducts exhibit variable morphological patterns and biological behavior. This group of neoplasms includes some uncommon lesions that originate from the intercalated ducts, such as polymorphous low-grade adenocarcinoma, epithelial-myoepithelial carcinoma and basal cell adenocarcinoma, and other that arise from the excretory duct, such as the salivary duct carcinoma. One hundred and seventy-seven malignant neoplasms of the major and minor salivary glands were reviewed. There were 23 cases of uncommon types of ductal carcinomas. Age, sex, location, size of tumor were examined as well as their histopathological features. There were four polymorphous low-grade adenocarcinomas (17.3%), two of which were located on the palate and two on the cheek; seven epithelial-myoepithelial carcinomas (30.4%), most of them located in the parotid; six basal cell adenocarcinomas (26%) which predominated in the submandibular gland, and there were six salivary duct carcinomas (26%), four of which occurred in the parotid gland, and two in the submandibular gland.

Well-differentiated intraosseous osteosarcoma of the jaws: experience of two cases from the Instituto Nacional de Cancerología, México.

Osteosarcomas of the jaws represent less than 10% of all osteosarcomas, and most of them are high-grade neoplasms. Prognostic factors in overall survival include tumor size, location and histologic grade. Examples of well-differentiated (low-grade) intraosseous osteosarcomas of the jaws (WDIOJ) have been rarely reported. This article presents two cases of this unusual lesion, one of which was located in the maxilla of a 17-year-old man and the other developed in the mandible of a 37-year-old woman. CT scan was necessary to detect the small foci of penetration into the thinned cortical bone and the reactive periosteal bone formation, which are important findings to establish the correct diagnosis of WDIOJ and help to exclude other benign intraosseous lesions that may be very similar histologically, such as fibrous dysplasia, ossifying and desmoplastic fibromas. In spite of tumor size (mean 5.2 cm), their well-demarcated borders allowed complete removal of both tumors. There is no evidence of tumoral activity in any of our patients after follow-up periods of 15 months and 5 years. Wide excision seems to be the treatment of choice for this subgroup of osteosarcomas.