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Common sites for squamous metaplasia include the bladder and cervix. Smokers often exhibit squamous metaplasia in the linings of their airways. These changes don't signify a specific disease, but rather usually represent the body's response to stress or irritation. Vitamin A deficiency or overdose can also lead to squamous metaplasia. [1]
Predictors associated with worse prognosis of MBC include age younger than 39 years at presentation, tumor invasion of the skin, and squamous cell carcinoma spread to the lymph nodes. The 5-year survival rate for MBC varies by classification, and ranges from 49% in the most deadly classifications to 64%.
However, that theory is also controversial since Hashimoto's thyroiditis and chronic lymphocytic thyroiditis (neoplasms to be shown [clarification needed] squamous metaplasia) are not associated with SCT. Primary STC is usually diagnosed in both lobes of the thyroid gland. The histopathology of STC shows a squamous differentiation of tumor cells.
In advanced cases, the epithelium undergoes pathologic changes, namely squamous metaplasia and loss of goblet cells. [14] Some severe cases result in thickening of the corneal surface, corneal erosion, punctate keratopathy , epithelial defects, corneal ulceration (sterile and infected), corneal neovascularization , corneal scarring, corneal ...
Barrett's esophagus is marked by the presence of columnar epithelia in the lower esophagus, replacing the normal squamous cell epithelium—an example of metaplasia. The secretory columnar epithelium may be more able to withstand the erosive action of the gastric secretions; however, this metaplasia confers an increased risk of adenocarcinoma. [16]
All squamous cell carcinoma lesions are thought to begin via the repeated, uncontrolled division of cancer stem cells of epithelial lineage or characteristics. Accumulation of these cancer cells causes a microscopic focus of abnormal cells that are, at least initially, locally confined within the specific tissue in which the progenitor cell resided.
Squamous-cell carcinoma (SCC) of the lung is a histologic type of non-small-cell lung carcinoma (NSCLC). It is the second most prevalent type of lung cancer after lung adenocarcinoma and it originates in the bronchi. Its tumor cells are characterized by a squamous appearance, similar to the one observed in epidermal cells.
Foci of squamous metaplasia and dysplasia may be present in the epithelium proximal to adenocarcinomas, but these are not the precursor lesions for this tumor. Rather, the precursor of peripheral adenocarcinomas has been termed atypical adenomatous hyperplasia (AAH). [ 10 ]