Review Note

Histopath SCC

◦ Irregular aggregates of atypical neoplastic keratinocytes arising from
epidermis invading into dermis
◦ Tumor aggregates are poorly circumscribed and vary markedly in size
and shape
◦ Neoplastic keratinocytes have vesicular nuclei, darker prominent
nucleoli, and abundant eosinophilic cytoplasm
◦ Nuclear pleomorphism common, with atypical hyperchromatic nuclei and
large nucleoli
◦ Dyskeratotic cells show pyknotic nuclei and homogenous, bright, “glassy”
eosinophilic cytoplasm
◦ Increased number of mitotic figures within neoplastic aggregates, many
often atypical Depending on degree of differentiation, neoplastic cells demonstrate
signs of keratinization such as formation of keratin pearls (concentric
whorls of eosinophilic parakeratotic cells). In contrast, poorly
differentiated tumors contain cells that are less epitheloid and less
eosinophilic and lack keratin pearls. The aggregates may be composed
of a few cells and can even become single cell infiltrates, making
it very challenging to distinguish on frozen sections without aid of
immunohistochemical stains.
◦ Areas of focal necrosis may be present
◦ Often a prominent inflammatory lymphocytic (or lymphohistiocytic)
infiltrate surrounds neoplastic aggregates