Fonseca I, Felix A, Soares J. Dedifferentiation in salivary gland carcinomas
Available from: Toshitaka Nagao
- "EMC containing a HG component has been described under various terms, including ‘‘HG carcinoma component in EMC,’’  ‘‘dedifferentiated EMC,’’ [30, 33, 34, 37, 42] “EMC with/of HGT,” [35, 36, 40, 41] ‘‘aggressive EMC’’  and ‘‘EMC with myoepithelial anaplasia’’ [33, 38]. Abrupt transition of the myoepithelial and/or ductal component of EMC into HG carcinoma is referred to as ‘‘dedifferentiated EMC’’ (Fig. 3a), whereas “myoepithelial anaplasia” is defined by Seethala et al.  as a gradual transition of the myoepithelial component of EMC into a more aggressive carcinoma. "
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ABSTRACT: "Dedifferentiation" and/or high-grade transformation (HGT) has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous low-grade adenocarcinoma, myoepithelial carcinoma, low-grade mucoepidermoid carcinoma and hyalinizing clear cell carcinoma, although the phenomenon is a rare event. Recent authors tend to preferably use the term HGT instead of "dedifferentiation" in these cases. HGT-tumors are composed of conventional carcinomas juxtaposed with areas of HG morphology, usually either poorly differentiated adenocarcinoma or "undifferentiated" carcinoma, in which the original line of differentiation is no longer evident. The HG component is generally composed of solid nests, sometimes occurring in cribriform pattern of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli and abundant cytoplasm. Frequent mitoses and extensive necrosis is evident. The Ki-67 labeling index is consistently higher in the HG component. p53 abnormalities have been demonstrated in the transformed component in a few examples, but the frequency varies by the histologic type. HER-2/neu overexpression and/or gene amplification is considerably exceptional. The molecular-genetic mechanisms responsible for the pathway of HGT in salivary gland carcinomas largely still remain to be elucidated. Salivary gland carcinomas with HGT have been shown to be more aggressive than conventional carcinomas with a poorer prognosis, accompanied by higher local recurrence rate and propensity for cervical lymph node metastasis, suggesting the need for wider resection and neck dissection.
Head and Neck Pathology 07/2013; 7(Suppl 1). DOI:10.1007/s12105-013-0458-8
Available from: Ana Flávia de Mattos Costa
- "Nevertheless, Di Palma et al. (1999) and Henley et al. (1997) showed negative expression of this protein in the dedifferentiated/high-grade component of AcCC  . Fonseca et al. and Sarode et al. also showed lack of specificity to p53 in both components of their cases of EMC  . These inconsistent results suggest that TP53 alteration is not the only mechanism for transformation in salivary gland tumors but may indicate a poor prognosis, similar to what is known for conventional AdCC . "
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ABSTRACT: The concept of dedifferentiation had previously been used in salivary gland carcinomas. Recently, the term "high-grade transformation" was introduced for adenoid cystic carcinoma, acinic cell carcinoma, epithelial-myoepithelial carcinoma, and polymorphous low-grade adenocarcinoma and may better reflect this phenomenon, although transformation into moderately differentiated adenocarcinoma (i.e., not "high grade") has also been described. Among the immunohistochemical markers, Ki-67 seems to be the only one that can help distinguish between the conventional and transformed components; however, the combination of morphological criteria is still sovereign. The overexpression of p53 was observed in the transformed component in all tumor types studied, despite few cases having been demonstrated to carry mutations or deletions in TP53 gene. Genetic studies in salivary gland tumors with dedifferentiation/high-grade transformation are rare and deserve further investigation. This paper aims at providing an overview on the recent concepts in histopathological classification of salivary gland tumors, complemented by immunohistochemical and genetic findings.
Pathology Research International 08/2011; 2011(2):325965. DOI:10.4061/2011/325965
American Journal of Surgical Pathology 11/2000; 24(10):1439-40. DOI:10.1097/00000478-200010000-00019 · 5.15 Impact Factor
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