Mammary analog secretory carcinoma (MASC)

  • Mammary analog secretory carcinoma (MASC):
    • Is a recently described salivary gland tumor:
      • That was likely classified as acinic cell carcinoma in the past
  • The tumor has striking histologic and molecular similarities:
    • To secretory carcinoma of the breast
  • Secretory carcinoma of the breast (SC):
    • Has shown to have a recurrent balanced chromosomal translocation:
      • t(12;15) (p13;q25):
        • Which leads to an oncogenic fusion gene ETV6-NTRK3
    • This translocation is also present in MASC:
      • This fusion gene encodes a chimeric tyrosine kinase:
        • That is known to play an important role on its oncogenesis
  • Immunohistochemical similarities between MASC and SC of the breast also include:
    • Being S100 protein, epithelial membrane antigen (EMA), and vimentin positive and “triple negative” (ER/PR/Her2 negative)
  • MASC predominantly affects:
    • Men and normally does not behave in an aggressive biology
  • The parotid gland is the most common affected gland by MASC
  • The official terminology of this entity:
    • Is now “secretory carcinoma”
  • At the histologic level:
    • Tumor cells have eosinophilic or clear bubbly cytoplasm:
      • They may grow as tubules or microcysts, papillae, or macrocysts
    • Secretions are almost always present:
      • In the microcysts and / or macrocysts
  • MASC characteristically harbors:
    • A balanced chromosomal translocation (12, 15):
      • Resulting in the formation of the ETV6–NTRK3 fusion genes
  • Even though they have similar growth rate between MASC and ACC:
    • MASC is more likely to metastasize to the regional lymph nodes:
      • It should be considered as a more aggressive tumor compared with the regular low grade ACC
  • MASC usually presents as a painless:
    • It is a non-tender mass that increases in size overtime
  • The majority of MASC arise from the parotid gland;
    • Accounting for two thirds of the reported cases
  • The mean age for presentation of MASC is 47 years:
    • In contrast with SC of the breast that usually occurs in younger patients
  • MASC:
    • Is considered a low-grade carcinoma with a favorable prognosis:
      • According to Skálová et al:
        • It has moderate risk for local recurrence (15%)
        • Lymph node metastases (20%)
        • Low risk for distant metastases (5%)
Neck magnetic resonance imaging of the head and neck showing the right parotid lesion.
Superficial parotidectomy with preservation of the facial nerve.
Hematoxylin and eosin staining.
Immunohistochemical study for S-100 protein.

#Arrangoiz #CancerSurgeon #HeadandNeckSurgeon #SurgicalOncologist #MASC #MammaryAnalogSecretoryCarcinoma #SalivaryGlandTumors #MSMC #MountSinaiMedicaCenter #Mexico #Miami

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