Carcinoma ex pleomorphic adenoma

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Carcinoma ex pleomorphic adenoma
Diagnosis in short

Carcinoma ex pleomorphic adenoma. H&E stain.

LM epithelial or myoepithelial cells with cytologic features of malignancy, pleomorphic adenoma (required if no history)
LM DDx salivary duct carcinoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, pleomorphic adenoma
Gross firm
Site salivary gland - usu. parotid gland

Clinical history pleomorphic adenoma (required if not present in assoc. with carcinoma)
Signs usu. mass lesion, firm
Prevalence uncommon
Prognosis dependent on stage, typically poor

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

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 parotid gland.[1]

Microscopic

Features:

  • Cells (epithelial or myoepithelial) 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

www:

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.

Sign out

PAROTID GLAND (MASS), LEFT, EXCISION:
- CARCINOMA EX PLEOMORPHIC ADENOMA, LOW-GRADE, INTRACAPSULAR.
-- MARGINS NEGATIVE.
-- SEE TUMOUR SUMMARY AND COMMENTS.
- THREE BENIGN LYMPH NODES.

Micro

The sections show a lesion with spindled (myoepithelial) cells and an epithelial component, on a background of a chondromyxoid stroma. The lesion is encapsulated by a thin layer of fibrous tissue.

Focally, within the lesion, nuclear atypia and mitotic activity are identified, including an atypical mitotic figure. The atypical region stains with p53. Approximately 45% of the atypical cells stain with Ki-67. There is no appreciable HER2 staining.

Unremarkable parotid gland and lymph nodes are present.

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.