Epithelial-Myoepithelial Carcinoma of the Salivary Glands

• Epithelial-myoepithelial carcinoma (EMC):
  • Is another typically indolent salivary gland tumor:
  • That is characterized by a multi-nodular pattern and biphasic or bilayered arrangement of inner ductal cells and outer myoepithelial cells, with classically clear cytoplasm
• EMC:
• Is a rare tumor with low malignant potential:
  • Accounting for less than 1 % of salivary neoplasms
• Peak incidence occurs in seventh decade:
  • With a predilection for female
• As early as 1956, EMC was reported as:
  • Adenomyoeipthelioma, clear cell adenoma, tubular solid adenoma and clear cell carcinoma:
    • Due to its varied histopathologic appearance
• The term EMC was coined by Donath et al. in 1972:
  • This discrete entity was subsequently incorporated in WHO classification of salivary gland tumors in 1991
• On histopathologic examination:
  • It shows dual cell population:
    • Composed of luminal ductal epithelial cells (inner layer) surrounded by large polygonal clear myoepithelial cells (outer layer):
      • Due to bidirectional differentiation of the stem cell
• The most common location is the parotid gland:
  • Also the index case has parotid involvement:
    • But it is also known to occur in submandibular gland and minor salivary glands of palate, base of tongue and rarely in breast, lung, kidney, uterus
• Rarely, it may show high grade transformation of epithelial or myoepithelial component:
  • Resulting in aggressive behavior
• Because of rarity of EMC a standard treatment guideline is not yet known:
  • Surgical resection is the most widely used approach:
    • Although, some of the reported cases have utilized post-operative radiotherapy (PORT) extrapolated from other salivary gland histologies
• Although it is a low grade tumor:
  • Local recurrence rates of 23% to 50 % have been reported:
    • With 25 % chance of distant metastasis
  • Local recurrence in as early as 6 months post operatively has been seen
• Histopathologic markers such as:
  • Solid growth pattern, nuclear atypia, DNA aneuploidy, necrosis, positive surgical margins and high proliferative activity:
    • Have been identified by some authors to be associated with more aggressive behavior and high frequency of local recurrences and metastases
• Surgery alone may not be sufficient in cases with histopathologic markers of aggressive behavior:
  • These patients may be candidates for PORT

#Arrangoiz #CancerSurgeon #HeadandNeckSurgeon #SurgicalOncologist #SalivaryGlandTumors #EpithelialMyoepithelialCarcinoma #EMC #MSMC #MountSinaiMedicalCenter #Mexico #Miami