Carcinoma ex pleomorphic adenoma

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Carcinoma ex pleomorphic adenoma, abbreviated ca ex PA, is a rare malignant salivary gland tumour that arise from a pleomorphic adenoma.

General

Definition:

Diagnosis (either 1 or 2):

  1. History of a pleomorphic adenoma at the same site.
  2. Features of a pleomorphic adenoma and a carcinoma.

Epidemiology:

  • Rare.

Microscopic

Features:

  • Cells with cytologic features of malignancy.
  • Architecture (any of the following):
    • Glands.
    • Nests.
    • Single cells (may be subtle).

Architectural patterns:

  • Ductal carcinoma NOS (arising from ductal cells) - most common pattern for Ca ex PA.
  • Myoepithelial cacinoma NOS (arising from myoepithelial cells).
  • "Named carcinoma":
    • Salivary duct carcinoma - second most common pattern for Ca ex PA.
    • Mucoepidermoid carcinoma.
    • Adenoid cystic carcinoma.

Note:

  • Often adenocarcinoma-like.
  • Myoepithelial cells may be clear cells.

Subclassification

Extent of invasion:[1]

  1. Non-invasive AKA intracapsular AKA in situ.
  2. Minimally invasive <=1.5 mm beyond the capsule.
  3. Widely invasive >1.5 mm beyond the capsule.

See also

References