Nasal cavity, paranasal sinuses, nasopharynx

• Acquired overgrowth of surface glands characterized by pseudostratified epithelium with cilia surrounded by a thickened basement membrane
• Currently classified as nonneoplastic hamartoma in the WHO classification 5th edition (Head Neck Pathol 2022;16:1)
• Chondro-osseous respiratory epithelial (CORE) hamartoma is considered a subtype of respiratory epithelial adenomatoid hamartoma (REAH) (Head Neck Pathol 2022;16:1)

• M:F = 3:1 to 7:1 (Ann Otol Rhinol Laryngol 1995;104:639, Am J Rhinol Allergy 2013;27:322)
• Median age: 58 years (range: 27 - 81 years) (Ann Otol Rhinol Laryngol 1995;104:639, Am J Rhinol Allergy 2013;27:322)

• Patients commonly present with nonspecific symptoms (e.g., nasal congestion / obstruction, headache, rhinorrhea and epistaxis)
• Often has a longstanding history of chronic rhinosinusitis (Ann Otol Rhinol Laryngol 1995;104:639)
• May be unilateral or bilateral (Ann Otol Rhinol Laryngol 1995;104:639, AJNR Am J Neuroradiol 2013;34:1086)

• Expansion of the maximum olfactory cleft width (especially when > 10 mm) is a common finding on computed tomography (CT) (Am J Rhinol Allergy 2013;27:322, AJNR Am J Neuroradiol 2013;34:1086)
• No evidence of destructive growth or bone invasion

Images hosted on other servers:

• 17 year old boy with respiratory epithelial adenomatoid hamartoma (Ear Nose Throat J 2022 May 9 [Epub ahead of print])
• 62 year old man with respiratory epithelial adenomatoid hamartoma of the maxillary sinus (Acta Otorhinolaryngol Ital 2006;26:225)
• 75 year old man with bilateral nasal mass (Proc (Bayl Univ Med Cent) 2017;30:221)
• 83 year old woman with chondro-osseous respiratory epithelial adenomatoid hamartoma (Case Rep Otolaryngol 2019;2019:5247091)

Images hosted on other servers:

Contributed by Bin Xu, M.D., Ph.D.

Respiratory epithelial adenomatoid hamartoma (REAH)


Chondro-osseous respiratory epithelial (CORE) hamartoma

• Inflammatory sinonasal polyp:
  • May have occasional invagination of surface epithelium but lacks proliferation of glandular component and the thickened surrounding basement membrane
• Sinonasal papilloma, inverted type:
  

  	Respiratory epithelial adenomatoid hamartoma	Sinonasal papilloma, inverted type
  Location	Commonly on the posterior septum close to the olfactory cleft	Typically on the lateral nasal wall
  High risk HPV	Negative	May be positive
  Thickened basement membrane	Present	Absent
  Epithelial lining	Respiratory type epithelium of normal thickness with cilia	Hyperplastic (thickened) squamous, transitional or respiratory type epithelium
  Transmigrating neutrophils / neutrophilic microabscesses	Absent	Present

  
  
• Sinonasal adenocarcinoma, nonintestinal type:
  • Complex architecture manifested as densely packed back to back tubular glands or fused / cribriform glandular architecture
  • Lacks cilia and thickened basement membrane
  • May show other malignant features (e.g., nuclear pleomorphism, prominent mitotic activity, necrosis, perineural invasion and lymphovascular invasion)
  • May harbor diagnostic mutations or fusions involving NTRK3, MET, NRG1, PRKACA, AKT1, BRAF and CTNNB1 genes (Mod Pathol 2022;35:1160)
• Biphenotypic sinonasal sarcoma:
  • Surface / glandular epithelium overlying biphenotypic sinonasal sarcoma may show changes resembling REAH
  • REAH lacks S100+ / desmin+ hypercellular spindle cell proliferation in between glands

An excision of a nasal polyp from 50 year old man shows the histology pictured above. What is the diagnosis?

1. Inflammatory sinonasal polyp
2. Respiratory epithelial adenomatoid hamartoma (REAH)
3. Sinonasal adenocarcinoma, nonintestinal subtype
4. Sinonasal papilloma, inverted subtype

B. Respiratory epithelial adenomatoid hamartoma (REAH). The H&E shows typical histologic findings of respiratory epithelial adenomatoid hamartoma, characterized by proliferation of medium sized glands with cilia surrounded by thickened basement membrane. See Differential diagnosis section for features to distinguish REAH from its diagnostic mimickers, such as inverted papilloma, inflammatory polyp and nonintestinal sinonasal adenocarcinoma.

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Reference: Respiratory epithelial adenomatoid hamartoma

Which of the following statements about respiratory epithelial adenomatoid hamartoma (REAH) is true?

1. 30% of REAH is associated with high risk human papillomavirus
2. Classified as a benign neoplasm in the WHO classification
3. Commonly located on the nasal septum rather than lateral nasal wall
4. Has ~15% risk of recurrence and a small risk of distant metastasis

C. Commonly located on the nasal septum rather than lateral nasal wall. Answer A is incorrect because REAH is not associated with high risk human papillomavirus. Answer B is incorrect because REAH is classified as a nonneoplastic lesion in WHO classification. Answer D is incorrect because REAH has a very low (if any) risk of recurrence if completely excised and no distant metastasis has been reported.

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Reference: Respiratory epithelial adenomatoid hamartoma