Hypopharyngeal cancer arises from squamous cells, which are cells that are normally involved in protection of aerodigestive tract. Hypopharyngeal cancer is a rare type of malignant cancer which has a delayed onset of clinical manifestations. Hypopharyngeal cancer is usually diagnosed at an advanced stage and it spreads to other organs such as lungs, mediastinum, bones, brain, liver, esophagus, and thyroid gland. The metastatic invasion depends on the anatomic location of the hypopharyngeal cancer. Hypopharyngeal cancer is mostly differentiated as squamous cell carcinoma, however, the undifferentiated type may be found in the pyriform sinus region. The exact pathogenesis of the hypopharyngeal cancer is not exactly understood, but the p16, cyclin D1, NOTCH1, and TP53 gene mutations have been associated with the development of the hypopharyngeal cancer. Hypopharyngeal cancer is associated with sideropenic dysphagia and Paterson Brown Kelly syndrome. On gross pathology, flattened plaques, mucosal ulceration, and raised margins of the lesion are the characteristic findings of hypopharyngeal cancer. On microscopic histopathological analysis, spindle cells, basaloid cells, and nuclear atypia are the characteristic findings of hypopharyngeal cancer.

• Hypopharyngeal cancer arises from squamous cells, which are cells that are normally involved in protection of aerodigestive tract.^[1]
• Development of hypopharyngeal cancer is the result of multiple genetic mutations. These mutations lead to activation of oncogenes and inactivation of tumor suppression genes which ultimately results in deregulated cellular proliferation.
• Overexpression of TP53 and cyclin D1 may lead to multiple primary cancers of the hypopharynx.

• Genes involved in the pathogenesis of hypopharyngeal cancer include:^[1][2]
  • p16
  • Cyclin D1
  • TP53
  • NOTCH1

• Hypopharyngeal carcinoma is associated with:^[2]
  • Sideropenic dysphagia
  • Paterson-Brown-Kelly syndrome

• On gross pathology, hypopharyngeal cancer is characterized by:^[2]
  • Flattened plaques
  • Raised margins of the lesion
  • Mucosal ulceration
  • Tumor spread to piriform sinus
  • Exophytic

• On microscopic histopathological analysis, hypopharyngeal carcinoma is characterized by:^[2]
  • Spindle cells
  • Basaloid cells
  • Nuclear atypia
  • Abundant chromatin

• There are some immunohistochemistry markers involve in the hypopharyngeal cancer:^[2]

• • Beta catenin positive
  • C-erbB2 negative
  • mRNA translation initial factor positive