What are the histologic grades for conventional cutaneous squamous cell carcinoma (cSCC)?

Updated: Jul 08, 2020
  • Author: Talib Najjar, DMD, MDS, PhD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Conventional cSCC can be divided into the following four histologic grades, based the degree of nuclear atypia and keratinization found (see the image below):

  • Well differentiated - Characterized by more normal-appearing nuclei with abundant cytoplasm and extracellular keratin pearls

  • Moderately differentiated - Exhibits features intermediate between well-differentiated and poorly differentiated lesions

  • Poorly differentiated - Shows a high degree of nuclear atypia with frequent mitoses, a greater nuclear-cytoplasmic ratio, and less keratinization

  • Highly undifferentiated - Shows epithelial cells that may be difficult to distinguish from mesenchymal, melanoma, or lymphoma cells

    Squamous cell carcinoma. The lesion closely approx Squamous cell carcinoma. The lesion closely approximates the specimen in the previous image. Field cancerization is illustrated; that is, if >1 cell is exposed to a carcinogen, >1 cell becomes cancerous. Note the marked inflammatory-cell response. Should limited biopsy reveal only severe atypia with a severe inflammatory response, the lesion should be investigated further, because a cancer is likely nearby.

Other histologic variants include acantholytic (adenoid) SCC, which is characterized by a pseudoglandular appearance, and spindle cell SCC, which has atypical, spindle-shaped cells. Both of these variants exhibit a more aggressive clinical course.

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