Squamous cell carcinoma

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This article deal with squamous cell carcinoma, also squamous carcinoma, a very common epithelial derived malignant neoplasm that can arise from many sites. It is commonly abbreviated SCC.

Sites

Skin

Head and neck

Uterine cervix

Vulva

Lung

Other sites

Microscopic

Classification

SCC is subdivided by the WHO into:[1]

  • Keratinizing type (KT).
    • Worst prognosis.
  • Undifferentiated type (UT).
    • Intermediate prognosis.
    • EBV association.
  • Nonkeratinizing type (NT).
    • Good prognosis.
    • EBV association.

Features based on classification:[1]

  • KT subtype:
    • Keratinization & intercellular bridges through-out most of the malignant lesion.
  • UT:
    • Non-distinct borders/syncytial pattern.
    • Nucleoli.
  • NT:
    • Well-defined cell borders.

Invasive squamous cell carcinoma

Features:

  • Eosinophilia.
  • Extra large nuclei/bizarre nuclei.
  • Inflammation (lymphocytes, plasma cells).
  • Long rete ridges.
  • Numerous beeds/blobs of epithelial cells that seem unlikely to be rete ridges.

Pitfalls:

  • Tangential cuts.
    • If you can trace the squamous cells from a gland to the surface it is less likely to be invasive cancer.

Notes on invasion:

Image(s):

Subtypes

There are several subtypes:[3]

  • Adenosquamous carcinoma.
  • Ancatholytic squamous cell carcinoma.
  • Basaloid squamous cell carcinoma - poor prognosis, usu. diagnosed by recognition of typical SCC.
  • Carcinoma cuniculatum.
  • Verrucous carcinoma - good prognosis, rare.
  • Papillary squamous cell carcinoma.
  • Lymphoepithelial carcinoma - rare.
  • Spindle cell squamous carcinoma - a common spindle cell lesion of the H&N.

Verrucous squamous cell carcinoma

  • AKA verrucous carcinoma.

General

  • Good prognosis.

Microscopic

Features:

  • Exophytic growth.
  • Well-differentiated.
  • "Glassy" appearance.
  • Pushing border - described "elephant feet".

DDx:

  • Papilloma.

Image:

Spindle cell squamous carcinoma

General

  • Common spindle cell lesion of the head and neck.

Microscopic

Feature:

  • Histomorphologic key to the diagnosis: finding a component of conventional squamous cell carcinoma.
  • Malignant spindle cell neoplasm.

DDx:

  • Spindle cell melanoma.
  • Mesenchymal neoplasm.

IHC

  • Typically keratin -ve.
  • p63 +ve.

Basaloid squamous cell carcinoma

Features:

  • Need keratinization. (???)

DDx:

  • Neuroendocrine tumour.

Lymphoepithelial (squamous cell) carcinoma

This is discussed in detail in the lymphoepithelioma-like carcinoma (LELC) article.
In the head and neck this is a separate entity known as nasopharyngeal carcinoma.

General

  • Rare.
  • +/-EBV.
  • Some consider this a distinct entity - rather than a subtype of SCC.[6]

Microscopic

Features:

  • Malignant squamoid cells (eosinophilic cytoplasm, nuclear atypia).
  • Abundant mononuclear inflammatory cells (plasma cells, lymphocytes).

Images: see the LELC article.

See also

References

  1. 1.0 1.1 Mills, Stacey E; Carter, Darryl; Greenson, Joel K; Oberman, Harold A; Reuter, Victor E (2004). Sternberg's Diagnostic Surgical Pathology (4th ed.). Lippincott Williams & Wilkins. pp. 975. ISBN 978-0781740517.
  2. Wenig BM (March 2002). "Squamous cell carcinoma of the upper aerodigestive tract: precursors and problematic variants". Mod. Pathol. 15 (3): 229–54. doi:10.1038/modpathol.3880520. PMID 11904340. http://www.nature.com/modpathol/journal/v15/n3/pdf/3880520a.pdf.
  3. URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/LipOralCav_11protocol.pdf. Accessed on: 3 April 2012.
  4. URL: http://www.juniordentist.com/verrucous-carcinoma.html. Accessed on: 3 April 2012.
  5. URL: http://www.biomedcentral.com/1471-2407/6/146. Accessed on: March 9, 2010.
  6. Skinner, NE.; Horowitz, RI.; Majmudar, B. (Oct 2000). "Lymphoepithelioma-like carcinoma of the uterine cervix.". South Med J 93 (10): 1024-7. PMID 11147469.