Nasopharyngeal Carcinoma (NPC)

ūüĎČNasopharyngeal carcinoma (NPC) is rare in the Western Hemisphere, showing its highest incidence in the Alaskan Eskimo and Mediterranean populations; however, it is endemic in southern China.

  • The etiology of NPC is multifactorial and has:
    • Viral, genetic, and environmental factors
  • Undifferentiated subtype of NPC:
    • Is strongly associated with Epstein-Barr virus (EBV):
      • EBV is also associated with earlier lesions:
        • Such as carcinoma in situ
  • The nasopharynx extends anteriorly from the posterior choana of the nasal cavity to the free border of the soft palate:
    • It comprises a:
      • Vault
      • The lateral walls:
        • Including the fossa of Rosenm√ľller and mucosa covering the torus tubarius
      • A posterior wall
      • The superior surface of the soft palate:
        • Which is the floor
    • The posterior lip of the opening of the Eustachian tube is the torus tubarius:
      • Behind which is a mucosal fold:
        • Called the fossa of Rosenm√ľller
  • The World Health Organization (WHO) classification for NPC encompasses:
    • Keratinizing SCC
    • Nonkeratinizing carcinomas:
      • Well differentiated
      • Undifferentiated
    • Basaloid squamous cell carcinoma
  • Keratinizing SCC (type 1):
    • Is more common in North America:
      • Not associated with EBV
  • Nonkeratinizing carcinoma, undifferentiated type (type 2b):
    • Is highly associated with EBV
    • Accounts for 60% of all NPCs in adults
    • The most frequent type in the pediatric population
  • The first-echelon lymphatic drainage of NPC includes the :
    • Retropharyngeal lymph nodes
    • Superior jugular lymph nodes
    • Posterior cervical chain nodes
  • Lymph node metastasis from NPC is common:
    • As many as 90% of patients:
      • Have evidence of unilateral nodal involvement
    • As many as 50% of patients:
      • Have evidence bilateral nodal involvement
  • The nasopharynx is the upper one-third of the pharynx and is separated from the oropharynx below by the soft palate:
    • Anatomically:
      • It is the space situated behind the nasal cavities
      • Its mucosal lining starts immediately behind the posterior choana
      • It is actually located in the center of the head:
        • It is located more than 10 cm from the skin surface of the head in all directions
      • The undersurface of the body of the sphenoid bone:
        • Forms the roof (vault) of the nasopharynx:
          • Which slants downwards to form the posterior wall of the nasopharynx:
            • In front of the arch of the atlas and upper part of the body of the axis vertebrum
      • The floor of the nasopharynx:
        • Is formed by the upper surface of the soft palate:
          • Which separates the nasopharynx from the oropharynx below
        • The lateral wall of the nasopharynx is formed by:
          • The opening of the Eustachian tubes superiorly
          • The upper part of the superior pharyngeal constrictor muscle inferiorly
          • The orifice of the Eustachian (auditory tympanic) tube is delineated by:
            • An incomplete cartilaginous ring:
              • The deficient portion is in the inferolateral aspect
              • The medial portion of the cartilaginous ring:
                • Elevates the overlying mucosa to form the medial crusa:
                  • Also known as the Torus tubarus
                • The slit-like space formed by this medial crusa and the posterior wall of the nasopharynx:
                  • Is the fossa of Rosenm√ľller
  • The muscular wall of the nasopharynx is formed by the:
    • Superior pharyngeal constrictors lying deep to the pharyngobasilar fascia:
      • The fascial sheets join:
        • To form a median raphe:
          • Which extends from the skull base downwards along the entire posterior pharyngeal wall
  • The lymph nodes that drain the nasopharynx:
    • Lie in the retropharyngeal space:
      • Outside the pharyngobasilar fascia
      • In front of the prevertebral fascia
  • The cranial nerves IX, X, XI and XII, the carotid sheath and the sympathetic trunk:
    • Traverse the parapharyngeal space:
      • Which is lateral to the superior pharyngeal constrictor
  • The roof (vault) of the nasopharynx:
    • Is lined by pseudostratified ciliated epithelium
  • The posterior wall of the nasopharynx:
    • Is lined with stratified squamous cells:
      • The epithelium has a well-defined basement membrane and there is abundant lymphatic tissue in the lamina propria:
        • This lymphoid tissue forms the pharyngeal tonsil or adenoid in children
  • Branches of the internal maxillary artery:
    • Supply the nasopharynx
  • Venous drainage is to the:
    • Pterygoid venous plexus:
      • Then to the facial and internal jugular veins
  • The sensory nerve supply of the region:
    • Is from branches of the maxillary nerve (V2)
  • The lymphatic supply of the nasopharynx drains into the retropharyngeal lymph nodes:
    • Efferent lymphatics from these nodes and those that come directly from the nasopharynx:
      • Drain to the deep cervical lymph nodes:
        • The lymphatic drainage then passes down the neck nodes in an orderly fashion:
          • From the high neck nodes to the lower ones

#Arrangoiz #HeadandNeckSurgeon #CancerSurgeon #SurgicalOncologist #NasopharyngealCancer #Teacher #Surgeon

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