Uterus, Endometrium - Metaplasia, Squamous
Squamous metaplasia of the endometrial epithelium ( Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , and Figure 6 ) can develop spontaneously and also occurs as a result of hormonal changes following administration of compounds with estrogenic activity, such as genistein, diethylstilbestrol, and dioxins. Vitamin A deficiency also causes squamous metaplasia. The lesion is characterized by the replacement of the normally columnar endometrial epithelium by squamous epithelium. In some cases, the endometrial glands can also be affected ( Figure 7 and Figure 8 ). Keratinization is not uncommon with squames and other cellular debris in the lumen. Inflammation and cystic hyperplasia of the endometrium are frequently seen with squamous metaplasia.
Uterus, Endometrium - Metaplasia, Squamous should be diagnosed and given a severity grade whenever present. The modifier "squamous" should be included in the diagnosis to clearly define the lesion and eliminate potential confusion. Coexisting changes such as inflammation and hyperkeratosis should not be diagnosed separately unless warranted by severity.
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