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Antrochoanal Polyp | Nasal Polyps | Nose | Otorhinolaryngology (Ear Nose Throat / E.N.T) | 4th Year (Fourth Year) | MBBS | Detailed Free Notes

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1. EXAM-READY DEFINITION

  • Antrochoanal polyp is a benign, non-neoplastic, inflammatory polypoidal lesion that originates from the mucosa of the maxillary sinus (antrum) and extends through the maxillary ostium into the nasal cavity, finally projecting posteriorly into the choana and sometimes the nasopharynx.

  • It is characteristically:

    • Single

    • Unilateral

    • More common in children and young adults

  • Unlike ethmoidal polyps, antrochoanal polyp is not associated with allergy and does not arise from ethmoid sinuses.

One-Line for Exams

Antrochoanal polyp is a solitary unilateral inflammatory polyp arising from the maxillary sinus and extending into the choana.

2. TERMINOLOGY & POSITION IN NASAL POLYP CLASSIFICATION

2.1 TERMINOLOGY

  • Also called:

    • Killian’s polyp

  • Named after Killian, who first described it.

2.2 CLASSIFICATION CONTEXT

Inflammatory Nasal Polyps

  • Ethmoidal (mucous) polyps

    • Multiple

    • Bilateral

    • Allergy-associated

  • Antrochoanal polyp

    • Single

    • Unilateral

    • Maxillary sinus origin

Examiner Trap

  • Calling an antrochoanal polyp “ethmoidal” → major mistake

3. EPIDEMIOLOGY (WITH EXAM IMPLICATIONS)

3.1 AGE

  • Common in:

    • Children

    • Adolescents

    • Young adults

  • Rare in older adults

3.2 SEX

  • Slight male predominance

3.3 LATERALITY

  • Almost always unilateral

  • Bilateral antrochoanal polyps are extremely rare

3.4 ASSOCIATIONS

  • Chronic maxillary sinusitis

  • Recurrent upper respiratory infections

  • Not strongly associated with allergy or asthma

Key Contrast

  • Allergy → Ethmoidal polyp

  • Infection → Antrochoanal polyp

4. DETAILED APPLIED ANATOMY (VERY HIGH-YIELD)

4.1 MAXILLARY SINUS (ANTRUM) — OVERVIEW

  • Largest paranasal sinus

  • Pyramidal in shape

  • Lined by respiratory epithelium

  • Drains into:

    • Middle meatus via maxillary ostium

4.2 OSTIUM OF MAXILLARY SINUS

  • Located high on the medial wall of the sinus

  • Drainage is against gravity

  • Predisposes to:

    • Secretion retention

    • Chronic inflammation

4.3 CHOANA (IMPORTANT FOR EXTENSION)

  • Posterior nasal aperture

  • Leads into nasopharynx

  • Antrochoanal polyp grows:

    • From antrum → nasal cavity → choana → nasopharynx

4.4 WHY MAXILLARY SINUS IS INVOLVED

  • Poor drainage due to high-placed ostium

  • Frequent infections

  • Retained secretions cause mucosal edema

5. ETIOLOGY (STEP-WISE, EXAM-ORIENTED)

5.1 CHRONIC MAXILLARY SINUSITIS (PRIMARY CAUSE)

  • Recurrent infections

  • Persistent mucosal inflammation

  • Leads to mucosal edema and cyst formation

5.2 OBSTRUCTION OF SINUS DRAINAGE

  • Deviated nasal septum

  • Enlarged turbinates

  • Narrow ostium

5.3 SECONDARY FACTORS

  • Repeated upper respiratory tract infections

  • Poor sinus ventilation

Important

  • Allergy plays minimal role in antrochoanal polyp

6. PATHOGENESIS (CORE EXAM SECTION)

6.1 BASIC MECHANISM

  • Chronic inflammation of maxillary sinus mucosa →

  • Formation of retention cyst or localized mucosal edema →

  • Gradual expansion into sinus cavity →

  • Protrusion through maxillary ostium →

  • Extension into nasal cavity →

  • Posterior growth into choana

6.2 STEP-BY-STEP PATHOGENESIS

  1. Chronic infection of maxillary sinus

  2. Edema of sinus mucosa

  3. Retention cyst formation

  4. Progressive enlargement

  5. Herniation through ostium

  6. Extension into middle meatus

  7. Posterior growth into choana and nasopharynx

6.3 STRUCTURAL PARTS OF ANTROCHOANAL POLYP

  • Antral part (within maxillary sinus)

  • Nasal part (within nasal cavity)

  • Choanal part (posterior extension)

Exam Pearl

  • Removing only nasal part → high recurrence

7. GROSS MORPHOLOGY (CLASSICAL DESCRIPTION)

  • Single, elongated, pear-shaped mass

  • Smooth surface

  • Pale or greyish

  • Soft and gelatinous

  • Insensitive to touch

  • Does not bleed on probing

8. HISTOPATHOLOGY (EXAM-SCORING)

8.1 SURFACE EPITHELIUM

  • Pseudostratified ciliated columnar epithelium

8.2 STROMA

  • Edematous connective tissue

  • Few blood vessels

  • Less eosinophils compared to ethmoidal polyps

8.3 INFLAMMATORY CELLS

  • Lymphocytes

  • Plasma cells

  • Neutrophils (if infected)

Key Difference

  • Eosinophils not prominent → supports non-allergic origin

9. CLINICAL FEATURES — SYMPTOMS (WITH REASONING)

9.1 NASAL OBSTRUCTION

  • Unilateral

  • Progressive

  • Due to mechanical blockage

9.2 NASAL DISCHARGE

  • Mucoid or mucopurulent

  • Often unilateral

9.3 POSTNASAL DRIP

  • Especially when polyp reaches choana

9.4 MOUTH BREATHING & SNORING

  • Due to posterior nasal obstruction

9.5 CHANGE IN VOICE

  • Hyponasal speech

10. SYMPTOMS USUALLY ABSENT (IMPORTANT DIFFERENTIATION)

  • Sneezing

  • Itching

  • Epistaxis

Presence suggests:

  • Allergy

  • Tumor

11. SIGNS ON EXAMINATION

11.1 ANTERIOR RHINOSCOPY

  • Single pale polyp in middle meatus

  • Unilateral

  • Smooth and insensitive

11.2 POSTERIOR RHINOSCOPY

  • Polyp seen hanging in choana

  • May be visible behind soft palate

12. INVESTIGATIONS — INTRODUCTORY OVERVIEW

12.1 CT SCAN PARANASAL SINUSES

  • Unilateral maxillary sinus opacification

  • Polyp extending into nasal cavity and choana

  • No bone destruction

(Full investigation & management in Part 2)

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

13. DIFFERENTIAL DIAGNOSIS (EXAM-CRITICAL TABLES)

13.1 DIFFERENTIAL DIAGNOSIS OF A UNILATERAL NASAL MASS

Feature Antrochoanal Polyp Ethmoidal Polyp Hypertrophied Turbinate Inverted Papilloma Nasopharyngeal Tumor
Number Single Multiple Single Single Single
Side Unilateral Bilateral Bilateral Unilateral Unilateral
Origin Maxillary sinus Ethmoid sinus Inferior turbinate Lateral nasal wall Nasopharynx
Age Children/Young adults Adults Any Middle-aged Adolescents/Adults
Allergy No Yes No No No
Bleeding No No May bleed Frequent Common
CT Maxillary opacity + choanal extension Ethmoid opacification Turbinate enlargement Bone remodeling Mass ± bone erosion

Examiner Trap

  • Calling a single unilateral polyp ethmoidal → wrong

  • Missing nasopharyngeal extension on posterior rhinoscopy → loss of marks

14. INVESTIGATIONS (STEP-WISE, EXAM-SCORING)

14.1 CT SCAN PARANASAL SINUSES — GOLD STANDARD

Why Mandatory

  • Confirms diagnosis

  • Demonstrates site of origin (maxillary sinus)

  • Shows choanal extension

  • Essential for surgical planning

Typical CT Findings

  • Unilateral maxillary sinus opacification

  • Soft tissue mass extending through maxillary ostium

  • Posterior choanal extension

  • No bone destruction

Exam Line

CT scan of paranasal sinuses is mandatory before surgery in antrochoanal polyp.

14.2 NASAL ENDOSCOPY

  • Visualizes:

    • Site of origin

    • Extent into choana/nasopharynx

  • Helps differentiate from tumors

  • Assists surgical planning

14.3 MRI (SELECTIVE USE)

  • Indications:

    • Doubtful diagnosis

    • Suspected tumor

  • Helps differentiate:

    • Polyp vs neoplasm

    • Soft tissue characteristics

14.4 LAB TESTS

  • Not routinely required

  • Allergy workup usually normal

15. MEDICAL MANAGEMENT (LIMITED ROLE)

15.1 WHY MEDICAL TREATMENT IS INEFFECTIVE

  • Polyp has a large antral component

  • Poor drug penetration into maxillary sinus

  • High recurrence without surgery

15.2 WHEN MEDICAL THERAPY IS USED

  • Pre-operative optimization

  • Temporary symptom relief

Drugs

  • Nasal decongestants (short term)

  • Antibiotics if sinus infection present

  • Intranasal steroids (adjunct only)

Exam Pearl

  • Medical therapy alone is not curative

16. SURGICAL MANAGEMENT (CORE EXAM SECTION)

16.1 PRINCIPLES OF SURGERY

  • Complete removal of:

    • Nasal part

    • Choanal part

    • Antral part (most important)

  • Restore sinus drainage

  • Prevent recurrence

16.2 SURGICAL OPTIONS

A. SIMPLE POLYPECTOMY (OBSOLETE)

  • Removes only nasal part

Disadvantages

  • Very high recurrence

  • Does not address antral origin

B. CALDWELL–LUC OPERATION (CLASSICAL METHOD)

Indications

  • Large antral component

  • Recurrent polyp

  • When endoscopy unavailable

Steps (EXAM-ORIENTED)

  1. Incision in canine fossa

  2. Entry into maxillary sinus

  3. Removal of antral polyp

  4. Creation of inferior meatal antrostomy

Disadvantages

  • Facial swelling

  • Risk to tooth buds

  • Not preferred in children

C. FUNCTIONAL ENDOSCOPIC SINUS SURGERY (FESS) — GOLD STANDARD

Why Preferred

  • Minimally invasive

  • Direct access to maxillary ostium

  • Complete clearance of antral disease

  • Low recurrence

16.3 FESS — DETAILED STEPS

  1. Diagnostic nasal endoscopy

  2. Uncinectomy

  3. Widening of maxillary ostium

  4. Removal of polyp from sinus

  5. Clearance of choanal extension

  6. Preservation of healthy mucosa

16.4 ADVANTAGES OF FESS

  • Better visualization

  • Less morbidity

  • Faster recovery

  • Lower recurrence

16.5 COMPLICATIONS OF SURGERY

  • Bleeding

  • Synechiae

  • Infection

  • Recurrence (if antral part missed)

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

17. POST-OPERATIVE CARE

  • Nasal saline douching

  • Short-term antibiotics if indicated

  • Intranasal steroid sprays

  • Regular endoscopic follow-up

18. RECURRENCE — CAUSES & PREVENTION

18.1 CAUSES

  • Incomplete removal of antral part

  • Persistent sinus infection

  • Poor follow-up

18.2 PREVENTION

  • Complete surgical clearance

  • Proper sinus ventilation

  • Regular follow-up

19. OSCE / PRACTICAL STATIONS

19.1 SPOT DIAGNOSIS

  • Single unilateral pale polyp reaching choana

Diagnosis: Antrochoanal polyp

19.2 INVESTIGATION STATION

  • CT showing unilateral maxillary opacity + choanal extension

19.3 MANAGEMENT STATION

  • Treatment of choice: FESS

20. LONG CASE (UNIVERSITY STYLE)

Presentation

  • 14-year-old with unilateral nasal obstruction and postnasal drip

Examination

  • Single pale mass in middle meatus extending posteriorly

Diagnosis

  • Antrochoanal polyp

Management

  • CT PNS → Endoscopic removal (FESS)

21. MCQs

1. Most common sinus of origin of antrochoanal polyp:
A. Ethmoid
B. Frontal
C. Maxillary
D. Sphenoid
Correct Answer: C

2. Treatment of choice:
A. Steroids
B. Polypectomy
C. Caldwell–Luc
D. FESS
Correct Answer: D

22. VIVA QUESTIONS

  • Define antrochoanal polyp

  • Differences from ethmoidal polyp

  • Why recurrence occurs

  • Role of FESS

23. EXAMINER TRAPS

  • Removing only nasal part

  • Calling it allergic polyp

  • Skipping CT scan

  • Using medical therapy alone

24. CLINICAL PEARLS

  • Single, unilateral, non-allergic

  • Maxillary sinus origin

  • CT mandatory

  • FESS is gold standard

  • Recurrence if antral part not removed

25. RADIOLOGY–PATHOLOGY–CLINICAL CORRELATION (VERY HIGH-YIELD)

25.1 WHY THIS TRIAD IS TESTED

  • ENT examiners want to see whether the student can:

    • Correlate CT findings with pathological origin

    • Predict extent and complications

    • Plan definitive surgical management

  • Antrochoanal polyp is a classic condition where imaging directly dictates surgery.

25.2 CT FINDINGS WITH PATHOLOGICAL BASIS

CT Finding Pathological Explanation Clinical Importance
Unilateral maxillary sinus opacity Edematous inflamed sinus mucosa Confirms antral origin
Soft tissue mass through ostium Herniation of polyp Explains nasal obstruction
Choanal extension Posterior growth of polyp Causes mouth breathing, snoring
No bone destruction Non-neoplastic lesion Rules out malignancy
Smooth sinus walls Chronic pressure Differentiates from aggressive disease

Exam Line

Presence of unilateral maxillary sinus opacity with choanal extension on CT scan is diagnostic of antrochoanal polyp.

25.3 ROLE OF MRI (SELECTIVE BUT IMPORTANT)

  • Used when:

    • Diagnosis is uncertain

    • Tumor suspected

  • MRI helps differentiate:

    • Inflammatory polyp (hypointense on T₁, hyperintense on T₂)

    • Neoplastic lesions

26. COMPLICATIONS (LOCAL & POST-SURGICAL)

26.1 LOCAL COMPLICATIONS

  • Persistent unilateral nasal obstruction

  • Recurrent maxillary sinusitis

  • Postnasal drip

  • Hyponasal speech

26.2 NASOPHARYNGEAL EFFECTS

  • Snoring

  • Mouth breathing

  • Sleep disturbance

  • Feeding difficulty in children

26.3 POST-SURGICAL COMPLICATIONS

  • Bleeding

  • Synechiae formation

  • Infection

  • Recurrence (most important)

Key Point

  • Recurrence almost always due to incomplete removal of antral component

27. PROGNOSIS

27.1 NATURAL COURSE

  • Benign condition

  • Does not undergo malignant transformation

  • Progressive enlargement if untreated

27.2 POST-TREATMENT PROGNOSIS

  • Excellent if:

    • Antral part is completely removed

    • Proper sinus ventilation restored

  • Recurrence rate:

    • High with simple polypectomy

    • Very low with FESS

28. PREVENTION OF RECURRENCE (EXAM FAVORITE)

  • Complete removal of antral component

  • Adequate widening of maxillary ostium

  • Treatment of chronic sinus infection

  • Regular post-operative endoscopic follow-up

29. COMPARATIVE TABLE — FINAL EXAM SUMMARY

ANTROCHOANAL POLYP VS ETHMOIDAL POLYP

Feature Antrochoanal Polyp Ethmoidal Polyp
Number Single Multiple
Side Unilateral Bilateral
Origin Maxillary sinus Ethmoid sinus
Age Children/Young adults Adults
Allergy No Yes
Eosinophils Few Many
Surgery FESS / Caldwell-Luc FESS
Recurrence If antral part missed Common

30. OSCE / PRACTICAL STATIONS (FULL SET)

30.1 SPOT DIAGNOSIS

  • Specimen: Single elongated polyp

  • Question: Identify lesion

Answer: Antrochoanal polyp

30.2 HISTORY STATION

  • Unilateral nasal obstruction

  • Postnasal drip

  • Snoring

30.3 EXAMINATION STATION

  • Anterior rhinoscopy:

    • Single pale mass

  • Posterior rhinoscopy:

    • Polyp hanging in choana

30.4 MANAGEMENT STATION

  • Investigation: CT PNS

  • Treatment of choice: FESS

31. LONG CASE (UNIVERSITY FORMAT)

31.1 HISTORY

  • 12-year-old child

  • Unilateral nasal obstruction

  • Mouth breathing

  • Postnasal drip

31.2 EXAMINATION

  • Anterior rhinoscopy:

    • Single pale polyp

  • Posterior rhinoscopy:

    • Choanal extension

31.3 INVESTIGATIONS

  • CT scan:

    • Unilateral maxillary sinus opacity

31.4 FINAL DIAGNOSIS

  • Antrochoanal polyp

31.5 MANAGEMENT

  • Endoscopic removal (FESS)

  • Clearance of antral component

32. MCQs (HIGH-YIELD)

1. Antrochoanal polyp most commonly arises from:
A. Ethmoid sinus
B. Frontal sinus
C. Maxillary sinus
D. Sphenoid sinus
Correct Answer: C

2. Most important cause of recurrence:
A. Allergy
B. Infection
C. Incomplete antral clearance
D. Poor steroids
Correct Answer: C

3. Best surgical option:
A. Polypectomy
B. Caldwell-Luc
C. FESS
D. Inferior turbinectomy
Correct Answer: C

33. VIVA QUESTIONS (RAPID FIRE)

  • Define antrochoanal polyp

  • Why is it unilateral?

  • Why does it recur?

  • CT findings

  • Difference from ethmoidal polyp

  • Treatment of choice

34. EXAMINER TRAPS

  • Treating with medical therapy alone

  • Forgetting CT scan

  • Removing only nasal portion

  • Calling it allergic polyp

  • Missing choanal extension

35. FINAL CLINICAL PEARLS (MUST-REMEMBER)

  • Antrochoanal polyp is single and unilateral

  • Originates from maxillary sinus

  • Not allergy-related

  • CT PNS is mandatory

  • FESS is gold standard

  • Recurrence occurs if antral part is left behind

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

Hunain Zia

Hunain Zia has previously achieved considerable success in the high-school educational stream, gaining a massive 154 Total A Grades and 7 Major Distinctions, a process in which he broke/ set 11 different world records, including the most A grades ever achieved, most subjects ever appeared in, most distinctions, gaining distinctions across two separate boards (Pearson Edexcel and CAIE) within the same year/ ever, and even 19 hours of constant examination. All records stand intact today. Hunain pursued his Honors Accounting Degree from the prestigious Bentley University, and then completed an LLB (in Honors) from University of London. Currently, he manages multiple social and commercial projects, has founded digital streams and works tirelessly in the education sector.

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