Adenoid Cystic Carcinoma

  • Adenoid cystic carcinoma (ACC):
    • Accounts for approximately 10% of all salivary gland neoplasms
    • This is the most common malignant disorder:
      • To arise in the submandibular, the sublingual, and the minor salivary glands
    • More than two thirds (65%) of them arise from the:
      • Minor salivary glands
    • ACC are most commonly located within:
      • The oral cavity (palate) followed by:
        • The nasal cavity and nasopharynx
    • They were considered the most common malignant salivary gland tumor to involve the palate:
      • But they are now outnumbered at this site:
        • Polymorphous low-grade adenocarcinoma
    • ACC arise more often in:
      • Women than in men
    • ACC tend to affect adults:
      • In their fifth through seventh decades of life
    • ACC often present as
      • An otherwise asymptomatic mass
  • Its natural history demonstrates a paradox:
    • First:
      • Tumor growth is slow:
        • But its clinical course is unyielding and progressive
    • Second:
      • Operative intervention is usually possible:
        • But multiple local recurrences are the norm
    • Third:
      • Metastatic spread to regional lymph nodes is rare:
        • But distant spread to the lungs and bones is common:
          • 40% to 50% of the cases
    • Fourth:
      • 5-year survival rates are expectantly high:
        • But 10 to 20-year survival rates are dismally low [29]
  • Tumor stage is considered the most reliable indicator of overall outcome:
    • But some authors have questioned the importance of histologic subtyping
  • There is a strong positive correlation between site of origin and prognosis:
    • The more favorable outcome with major (relative to minor) salivary gland ACC:
      • Is attributed to the earlier discovery of the neoplasm at these more accessible locations
  • ACC is not encapsulated or partially encapsulated:
    • Infiltrates the surrounding tissue:
      • The risk of local failure is:
        • Approximately 50% with surgery alone
  • Histologically:
    • They have a basaloid epithelium clustered in nests in a hyaline stroma
    • ACC can be categorized into three growth patterns:
      • Cribriform pattern
      • Tubular pattern
      • Solid pattern
    • The most common histologic subtype is:
      • The cribriform type (44% of the cases)
        • Characterized by a “Swiss cheese” pattern of vacuolated areas
        • The prognosis for the cribriform subtype:
          • Is intermediate
    • The tubular subtype (35% of the cases):
      • Carries the best prognosis
      • Characterized by cords and nests of malignant cells
    • The solid subtype (21% of the cases):
      • Has the worst prognosis in terms of distant metastasis and long-term survival
      • Solid sheets of adenoid malignant cells characterize this subtype
  • A sole feature of ACC is:
    • The propensity for perineural invasion:
      • 50% to 70% of the cases:
        • Even with early stage tumors
    • It can spread centripetally through the skull base and peripherally along both named and unnamed nerves
    • For this reason, adjuvant radiation that includes the anatomic course of the regional named nerves is often recommended
  • Lymphatic spread is uncommon:
    • Consequently neck dissection or wide-field radiation to regional lymphatics:
      • Is rarely recommended
  • Skip metastasis are known to occur despite clear surgical margins
  • This malignancy is graded according to Szanto et al:
    • Cribriform or tubular (grade I)
    • Less than 30% solid (grade II)
    • Greater than 30% solid (grade III)
  • In patients treated by similar modalities:
    • The cribriform and tubular variants of ACC demonstrated:
    • No difference in the rate of distant metastases and overall survival:
      • The cribriform variant demonstrated a:
        • Significantly worse prognosis in terms of local recurrence rate (up to 47%)
  • References:
    • Spiro, R.H. and A.G. Huvos, Stage means more than grade in adenoid cystic carcinoma. American journal of surgery, 1992. 164: p.623-8.
    • Bradley, P.J., Adenoid cystic carcinoma of the head and neck:
      a review. Curr Opin Otolarngol Head Neck Surg. Vol. 12.
      2004: Lippincott Williams and Wilkins.
    • Martinez-Rodriguez, N., et al., Epidemiology and treatment
      of adenoid cystic carcinoma of the minor salivary glands: A
      meta-analytic study. Medicina oral, patologia oral y cirugia
      bucal, 2011.
    • Szanto, P.A., et al., Histologic grading of adenoid cystic
      carcinoma of the salivary glands. Cancer, 1984. 54(6): p.
    • Kumar, P.P., et al., Intracranial skip metastasis from parotid
      and facial skin tumors: mechanism, diagnosis, and
      treatment. Journal of the National Medical Association, 85(5): p. 369-
    • Gnepp, D.R., Malignant mixed tumors of the salivary glands:
      a review. Pathology annual, 1993. 28 Pt 1: p. 279-328.

#Arrangoiz #CancerSurgeon #HeadandNeckSurgeon #SurgicalOncologist #CASO #Miami #AdenoidCysticCarcinoma #SalivaryGlandTumors #SalivaryGlandMalignancies #CenterforAdvancedSurgicalOncology

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