Epigenetic targets of arsenic: emphasis on epigenetic modifications during carcinogenesis.

DNA methylation and histone modification promote opening and closure of chromatin structure, which affects gene expression without altering the DNA sequence. Epigenetic markers regulate the dynamic nature of chromatin structure at different levels: DNA, histone, noncoding RNAs, as well as the higher-order chromatin structure. Accumulating evidence strongly suggests that arsenic-induced carcinogenesis involves frequent changes in the epigenetic marker. However, progress in identifying arsenic-induced epigenetic changes has already been made using genome-wide approaches; the biological significance of these epigenetic changes remains unknown. Moreover, arsenic-induced changes in the chromatin state alter gene expression through the epigenetic mechanism. The current review provides a summary of recent literature regarding epigenetic changes caused by arsenic in carcinogenesis. We highlight the transgenerational studies needed to explicate the biological significance and toxicity of arsenic over a broad spectrum.

Maxillary plexiform ameloblastoma showing basaloid differentiation: Report of a rare case with review of literature.

Ameloblastoma is a benign, locally aggressive tumor originating from the odontogenic epithelium. It manifests as a slow growing swelling, causing expansion of the jaw bones. Radiologically, it presents as a unilocular or multilocular radiolucency exhibiting a characteristic soap bubble or honeycomb appearance. Ameloblastoma exhibits several histologic patterns of which basal cell variant is a rare entity. The present case report is that of a maxillary ameloblastoma exhibiting a basaloid differentiation that may put one in the mind of a basaloid squamous cell carcinoma or a basal cell carcinoma. Confirmation of such rare variants should be done not only based on histopathology but with the help of supplemental immunohistochemical analysis. The present case report helps in exposing a rare variant of ameloblastoma and emphasizes the role of advanced diagnostic aids such as immunohistochemistry in establishing the diagnosis.