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Case 468 - Discussion

Uploaded: 2011-02-10, Updated: 2011-02-10

 

Adenoid Cystic Carcinoma

  • Most common in submandibular, sublingual or minor salivary glands.

  • Clinical behavior

    • Low growing but aggressive.

    • 50% metastasize, often silently to lung or bone; frequent recurrences and often late.

    • 5 year survival 60%, 10 year 30%, 15 year 15%.

    • Recurrence rates: solid (100%), cribriform (89%), tubular (59%) patterns.

    • 15 year survival rates:  solid (5%), cribriform (26%), tubular (39%).

    • Poorer prognosis for dedifferentiated, p53+ tumors.

    • Better prognosis for tumors of palate or parotid gland.

  • Morphology

    • Patterns: cribriform, solid or tubular.

    • Small bland myoepithelial cells with scant cytoplasm and dark compact angular nuclei surround pseudoglandular spaces with PAS+ excess basement membrane material and mucin.

    • Peripheral perineurial invasion and small true glandular lumina.

    • No squamous differentiation; no extensive necrosis.

    • Dedifferentiation: irregular tumor islands, anaplastic cells, and desmoplastic stroma.

  • Grading

    • Low grade/grade 1: tubular and cribriform patterns are considered.

    • Intermediate grade/grade 2: 30% to ~70% solid

    • High grade/grade 3: predominantly solid

  • Positive stains

    • Duct cells: keratin, CEA, alpha-1-antichymotrypsin, S100, CD117/c-kit.

    • Cells around pseudoglandular spaces: S100, actin, variable keratin; dedifferentiated tumor - S100

  • Cytogenetics: loss of heterozygosity at 6q23-25 ( t[6;9][q21-24;p13-23] )

  • Differential diagnosis

    • Pleomorphic adenoma: not invasive, no perineurial invasion, squamous metaplasia and mesenchyme-like areas

    • Polymorphous low grade adenocarcinoma: palate, bland uniform cells, CD117 weak/negative

Reference: pathologyoutlines.com