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.

Carcinoma ex pleomorphic adenoma
Diagnosis in short
LM DDx salivary duct carcinoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, pleomorphic adenoma
Gross firm
Site salivary gland - usu. parotid gland

Signs usu. parotid mass, firm
Prevalence uncommon
Prognosis dependent on stage, typically poor

General

Definition:

Diagnosis (either 1 or 2):

  1. History of a pleomorphic adenoma at the same site (~25% of cases[1]).
  2. Features of a pleomorphic adenoma and a carcinoma.

Epidemiology:

  • Rare.
  • Prognosis dependent on stage:
    • Good for early lesions - like PA.[2]
    • Poor for advanced lesions.[1]

Gross

  • Usually mass lesion - typically partoid gland.[1]

Microscopic

Features:

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

Subtyping/patterns:

Notes:

  • Myoepithelial cells may be clear cells.

DDx:

Subclassification

Extent of invasion:[3]

  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.

Images

IHC

Features - ca ex PA versus PA:[2]

  • Ki-67 >35% of cells.
  • HER2 +ve membrane staining (3+ for high-grade, 2+ or less for low-grade).
  • p53 +ve.
  • AR +ve.

Others:[2]

  • CK7 +ve.
  • AE1/AE3 +ve.

See also

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Antony, J.; Gopalan, V.; Smith, RA.; Lam, AK. (Mar 2012). "Carcinoma ex pleomorphic adenoma: a comprehensive review of clinical, pathological and molecular data.". Head Neck Pathol 6 (1): 1-9. doi:10.1007/s12105-011-0281-z. PMID 21744105.
  2. 2.0 2.1 2.2 Di Palma, S. (Jul 2013). "Carcinoma ex pleomorphic adenoma, with particular emphasis on early lesions.". Head Neck Pathol 7 Suppl 1: S68-76. doi:10.1007/s12105-013-0454-z. PMID 23821206.
  3. URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/MajorSalGlands_11protocol.pdf. Accessed on: 2 April 2012.