Sunday, December 4, 2016

Tumor of the day: squamous cell carcinoma

Keratin pearl
Skin is made up stratified, keratinizing squamous epithelium. Normally, basal cells are basaloid, with nuclei and other organelles.  These nuclei and organelles, specially the nuclei, are bluish (basophilic). Their job is to create keratin that will act as a protective layer over the topmost layer of skin. As the epithelium matures, the cells migrate into higher levels and begin to lose their organelles and nuclei, becoming pinker and pinker (more eosinophilic) all the while.

So finding well-differentiated squamous cells carcinoma is a matter of finding a loss of that specific organization. The way I think of it is "look for pink where it's not supposed to be". Dysplastic cells start making keratin and maturing way faster than they should, or they refuse to mature as they rise into higher epithelial levels. Or both. Or maybe I just don't know enough about the process yet. 

Regardless, the most obvious examples of well-differentiated have islands of keratin coated with immature, dysplastic cells. They look very pretty, and old pathologists probably would agree with me because they're called "keratin pearls".

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