Correct Answer: C. Antrochoanal polyp
Antrochoanal polyp (Killian polyp) is a benign, solitary fibrous polyp that arises from the mucosa of the maxillary sinus and extends through the maxillary ostium into the nasopharynx. The key discriminating feature here is the bowing of the posterior wall of the maxillary sinus, which is pathognomonic for this condition. As the polyp grows within the confined maxillary sinus, it exerts pressure on the sinus walls, causing characteristic bowing of the posterior wall—a finding seen on CT/imaging that is virtually diagnostic. The clinical presentation in a 2-year-old with recurrent epistaxis and nasal obstruction lasting 1 year fits perfectly: the polyp obstructs the nasal airway and can cause epistaxis due to mucosal irritation and vascular engorgement. Unlike nasopharyngeal angiofibroma (which presents in adolescent males with severe epistaxis and is highly vascular), antrochoanal polyp is non-vascular, solitary, and typically presents with milder epistaxis. The diagnosis is confirmed by nasal endoscopy showing a smooth, pale, pedunculated mass extending from the maxillary ostium into the nasopharynx. Treatment is endoscopic removal with complete excision of the stalk to prevent recurrence. This is the most common benign sinonasal mass in children in Indian ENT practice.
Why the other options are wrong
A. Nasopharyngeal angiofibroma — Nasopharyngeal angiofibroma (juvenile angiofibroma) typically presents in adolescent males (10–25 years), not 2-year-olds. It is a highly vascular tumor causing severe, life-threatening epistaxis and produces a mass in the nasopharynx with a characteristic 'widening of pterygopalatine fossa' on imaging, not bowing of the maxillary sinus posterior wall. The clinical presentation and imaging findings do not match. B. Rhinosporidiosis — Rhinosporidiosis is a chronic granulomatous infection caused by Rhinosporidium seeberi, endemic in India and presenting with epistaxis and nasal mass. However, it typically shows a characteristic 'strawberry-like' appearance on endoscopy with multiple small polyps, not a single smooth polyp. Imaging does not show bowing of the maxillary sinus; instead, it shows localized mucosal involvement. The clinical course is more indolent. D. Rhinoscleroma — Rhinoscleroma is a chronic granulomatous infection caused by Klebsiella pneumoniae subsp. rhinoscleromatis, endemic in India. It presents with progressive nasal obstruction and crusting but does NOT present with a discrete nasal mass or bowing of the maxillary sinus. Imaging shows diffuse mucosal thickening and fibrosis, not a space-occupying lesion. Epistaxis is not a prominent feature.
High-Yield Facts
- Antrochoanal polyp (Killian polyp): arises from maxillary sinus mucosa, extends through maxillary ostium into nasopharynx—solitary, non-vascular, benign.
- Bowing of posterior maxillary sinus wall is the pathognomonic imaging sign of antrochoanal polyp due to mass effect within the confined sinus.
- Peak age of presentation: children and young adults; rare in infants but can present as early as 2 years with nasal obstruction and mild epistaxis.
- Endoscopic appearance: smooth, pale, pedunculated mass extending from maxillary ostium; may have a 'choanal' component visible in nasopharynx.
- Treatment: complete endoscopic excision with removal of the stalk from the maxillary sinus to prevent recurrence; recurrence rate <5% with complete removal.
- Differential from nasopharyngeal angiofibroma: antrochoanal polyp is non-vascular (pale), solitary, and arises from maxillary sinus; angiofibroma is highly vascular (red/bleeding), arises from sphenoid/pterygopalatine region, and occurs in older adolescent males.
Mnemonics
KILLIAN POLYP = Maxillary Sinus Origin Killian = Killian polyp (antrochoanal polyp). Arises from maxillary sinus, extends through ostium into nasopharynx. Bowing of posterior sinus wall = mass effect. Use this when you see 'bowing of maxillary sinus' on imaging in a child with nasal obstruction. ANTROCHOANAL vs ANGIOFIBROMA Antrochoanal = Antrum (maxillary sinus) origin, pale (non-vascular), solitary, child. Angiofibroma = Adolescent male, highly vascular (red/bleeding), pterygopalatine origin, severe epistaxis. Use when differentiating nasal masses in pediatric vs adolescent patients.
NBE Trap
NBE may pair 'recurrent epistaxis' with 'nasopharyngeal angiofibroma' to trap students who associate epistaxis with the more dramatic vascular tumor, overlooking that antrochoanal polyp also causes epistaxis (albeit milder) and has the pathognomonic imaging finding of maxillary sinus bowing.
Clinical Pearl
In Indian pediatric ENT practice, antrochoanal polyp is the most common benign sinonasal mass in children presenting with chronic nasal obstruction and mild epistaxis. The 'bowing sign' on CT is so characteristic that it is often the key to diagnosis before endoscopy; complete endoscopic removal with stalk excision is curative and prevents the recurrence seen with incomplete removal.
_Reference: Bailey & Love Ch. 63 (Nasal Polyps); Dhingra's Otorhinolaryngology Ch. 8 (Benign Sinonasal Lesions)_