Antrochoanal polyp: a transmission electron and light microscopic study

Area of Science:

• Otolaryngology
• Pathology
• Electron Microscopy

Background:

• Antrochoanal polyps (ACP) are sinonasal masses originating from the maxillary antrum.
• Nasal polyps (NP) are commonly associated with allergic rhinitis.
• Distinguishing the etiology of ACP is crucial for effective treatment.

Purpose of the Study:

• To compare the light microscopic and ultrastructural features of ACP and middle meatus nasal polyps (MMP).
• To investigate potential differences in cellular and tissue pathology between ACP and MMP.
• To elucidate the underlying etiological factors of ACP based on histological findings.

Main Methods:

• Seven ACP and seven MMP specimens were analyzed using light microscopy and transmission electron microscopy (TEM).
• Microscopic examination focused on epithelial integrity, cilia presence, goblet cell hyperplasia, endothelial cell status, inflammatory cell infiltration, squamous metaplasia, and basement membrane characteristics.
• Statistical analysis was performed to compare significant differences between the two polyp groups.

Main Results:

• ACP exhibited more numerous inflammatory cells (excluding eosinophils) and prominent endothelial cell destruction compared to MMP.
• MMP showed more goblet cell hyperplasia and a predominance of eosinophils.
• Squamous metaplasia of the surface epithelium was observed in ACP but not in MMP.

Conclusions:

• The histological profile of ACP, including high inflammatory cell counts and intact epithelium, suggests a chronic inflammatory origin, distinct from the allergic basis often seen in MMP.
• Endothelial cell destruction in ACP may indicate a chronic inflammatory process.
• These ultrastructural findings differentiate ACP from MMP and provide insights into their distinct pathogenetic mechanisms.