Antral Mucosa

Structure of Antral Mucosa

• Ciliated pseudostratified columnar (respiratory) epithelium - the same type that lines the nasal cavity
• Goblet cells scattered among the epithelial cells, which produce mucus
• A thin lamina propria (connective tissue layer) beneath the epithelium
• Submucosal glands that contribute to mucus secretion

Function

• The cilia beat in coordinated waves to transport mucus toward the maxillary ostium (the natural opening of the sinus), which drains into the middle meatus of the nasal cavity
• Mucus traps pathogens, dust, and debris
• The lining helps humidify and warm inhaled air passing through the sinuses

Clinical Relevance

• Sinusitis (rhinosinusitis): Inflammation of the antral mucosa is the hallmark of maxillary sinusitis. When the ostium becomes blocked, mucus builds up, bacteria grow, and the mucosa becomes swollen and inflamed
• Antral mucosa thickening: Seen on CT/X-ray as a sign of chronic maxillary sinusitis
• Mucosal stripping: In older surgical procedures (Caldwell-Luc surgery), the antral mucosa was sometimes stripped - this is now avoided because it can cause mucociliary dysfunction. Modern endoscopic sinus surgery (FESS) aims to preserve the mucosa
• TNM staging of maxillary sinus tumors: T1 is specifically defined as a tumor "limited to the antral mucosa with no erosion or destruction of bone" - so the term appears in cancer staging as well (Scott-Brown's Otorhinolaryngology)

Lupus Pernio

Lupus pernio: characteristic violaceous, indurated plaques on the nose - Andrews' Diseases of the Skin

Definition

Epidemiology

• More common in women, typically in the 4th or 5th decade
• Higher prevalence in Black patients
• Occurs in approximately 25% of patients with sarcoidosis (cutaneous sarcoidosis overall); lupus pernio is a subset

Clinical Features

• Brown to violaceous (red-purple), smooth, shiny, indurated plaques and nodules
• Classically symmetric distribution on:
  • Tip and alar rim of the nose (most characteristic)
  • Cheeks, lips, forehead
  • Earlobes
  • Digits (fingers)
• Can be very disfiguring
• Lesions rarely resolve spontaneously
• May mimic rhinophyma (rosacea-related nose enlargement)

Associated Systemic Involvement (Key Associations)

• Nasal mucosal and underlying bone involvement can cause nasal perforation and collapse of the nasal bridge, resembling granulomatosis with polyangiitis (GPA/Wegener's)
• ENT evaluation is always recommended
• Associated with chronic rather than acute sarcoidosis (unlike erythema nodosum, which marks acute/benign disease)

Other Named Sarcoidosis Syndromes (Comparison)

Histopathology

Diagnosis

1. Compatible clinical and radiologic presentation
2. Histologic evidence of non-caseating granulomas on skin biopsy
3. Exclusion of other granulomatous conditions (TB, fungal infection, GPA, foreign body reaction)

Treatment

• Corticosteroids (oral or intralesional) are first-line - lead to recovery or regression in most patients
• Hydroxychloroquine (antimalarial) - for skin-limited disease
• Methotrexate - for chronic, refractory cases (though caution: can cause ulceration in sarcoidosis skin lesions)
• Tumor necrosis factor (TNF) inhibitors (infliximab, adalimumab) - for severe, refractory disease
• Important caution: Laser treatment (even pulsed dye laser) can cause ulceration of lupus pernio lesions and should be avoided

Prognosis

• Andrews' Diseases of the Skin, p. 824
• Fitzpatrick's Dermatology, p. 602-603
• Harrison's Principles of Internal Medicine 22E

Antrochoanal Polyp (ACP)

What Is It?

The Characteristic "Dumbbell" Shape

Gross Appearance - Specimen

Antrochoanal polyp - surgical specimen. Note the large, smooth, pale, lobulated fleshy mass - Bailey & Love's Surgery

CT Imaging

(A) Coronal CT: polyp within left antrum extending through accessory ostium into middle meatus (arrow, star). (B) Axial CT: polyp fills left nasal cavity and extends through choana to fill the postnasal space (star) - Grainger & Allison's Diagnostic Radiology

Epidemiology

• Represents only ~4-6% of all nasal polyps
• Most common in young adults (3rd-5th decade), but also seen in children/adolescents
• More common in non-allergic patients (contrast with ethmoidal polyps, which are allergy-driven)
• Females slightly > males
• Always unilateral and solitary

Pathogenesis

1. Infection theory - chronic low-grade maxillary sinus infection triggers mucosal oedema and polyp formation (infection plays a bigger role than in ethmoidal polyps)
2. Vasomotor imbalance - autonomic dysfunction causing mucosal swelling
3. Retention cyst expansion - a mucus retention cyst in the antrum gradually enlarges, herniates through the posterior fontanelle, and develops a solid nasal/choanal tail
4. Nitric oxide - recent research implicates altered NO metabolism in the sinus mucosa

Clinical Features

• Progressive unilateral nasal obstruction - the dominant symptom
• Mouth breathing, especially in children
• Nasal discharge (watery or mucoid)
• Snoring, sleep disturbance
• Postnasal drip
• In large polyps - sensation of something in the throat or difficulty swallowing (oropharyngeal extension)
• Pain is generally not a feature

• Endoscopy/anterior rhinoscopy: pale, smooth, gelatinous/semitransparent mass in the nasal cavity, often seen emerging from the middle meatus
• Posterior rhinoscopy/nasopharyngoscopy: mass seen prolapsing into or filling the nasopharynx
• The mass is avascular and pale (distinguishing it from angiofibroma, which is vascular and red/pink)
• Mobile and insensitive to probing (distinguishing from hypertrophied turbinate or tumour)

Comparison: ACP vs. Ethmoidal Polyps

Differential Diagnosis

• Juvenile nasopharyngeal angiofibroma - most important DD in young males; vascular, bleeds easily, red/purple, arises from posterior nasal wall
• Nasal tumours (inverted papilloma, malignancy) - must be excluded especially in adults with unilateral disease; requires imaging and biopsy
• Meningocele/encephalocele - in children; CT of anterior skull base mandatory before biopsy
• Mucous retention cyst - stays within the antrum, does not prolapse into nasal cavity

Investigations

1. CT scan (paranasal sinuses) - investigation of choice
   • Shows the dumbbell-shaped mass filling the antrum, passing through the ostium, and extending to the choana/nasopharynx
   • No bony destruction (distinguishes from malignancy)
   • Soft tissue density with the antral component appearing hypodense (cystic)
2. Nasal endoscopy - confirms origin, extent, and character of the lesion; mandatory to exclude sinister pathology before "simple polypectomy"
3. MRI - better soft-tissue contrast; useful when CT is inconclusive or malignancy is suspected

Treatment

• Endoscopic removal via the middle meatus with complete excision of both the nasal/choanal portion AND the antral cystic component
• The antral portion is the key - if left behind, the polyp will recur
• A middle meatal antrostomy provides access to the maxillary sinus to remove the antral component
• Curved powered instruments (microdebriders) or grasping forceps under endoscopic visualisation help retrieve the intrasinus portion
• If needed, a small inferior meatal antrostomy can be created temporarily for additional access

• Sublabial (transcanine) approach or inferior meatus approach - as supplementary routes when endoscopic access is limited
• Caldwell-Luc surgery (open approach via canine fossa) - historically used; now reserved for exceptional cases only. Stripping of the maxillary sinus mucosa is NOT necessary and should be avoided

Recurrence

• If completely removed including the antral component - recurrence is unlikely
• If only the nasal/choanal portion is avulsed (simple polypectomy) without removing the intrasinus cyst, recurrence is the rule