AJCC CLASSIFICATION OF Squamous cell carcinoma of maxillary sinus. Enumerate all investigations needed to stage and diagnose the sac of maxillary sinus according to Standard ENT textbook

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Squamous Cell Carcinoma of Maxillary Sinus: AJCC Classification & Investigations

PART I: AJCC (8th Edition) TNM Classification - Maxillary Sinus

T (Primary Tumour) Classification

T Category	Description
TX	Primary tumour cannot be assessed
Tis	Carcinoma in situ
T1	Tumour limited to the antral mucosa with no erosion or destruction of bone
T2	Tumour causing bone erosion or destruction, except for the posterior antral wall; including extension into the hard palate and/or middle meatus
T3	Tumour invades any of: bone of the posterior wall of maxillary sinus, subcutaneous tissues, skin of cheek, floor or medial wall of orbit, infratemporal fossa, pterygoid plates, ethmoid sinus
T4a	Moderately advanced: tumour invades anterior orbital contents, skin of cheek (full thickness), pterygoid plates, infratemporal fossa, cribriform plate, sphenoid or frontal sinuses
T4b	Very advanced: tumour invades orbital apex, dura, brain, middle cranial fossa, cranial nerves other than V2, nasopharynx, or clivus

Note: T4a = resectable, moderately advanced; T4b = unresectable, very advanced

N (Regional Lymph Nodes) Classification

N Category	Description
NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in a single ipsilateral lymph node, ≤3 cm, no extranodal extension (ENE-)
N2a	Single ipsilateral node >3 cm but ≤6 cm, ENE-
N2b	Multiple ipsilateral nodes, none >6 cm, ENE-
N2c	Bilateral or contralateral nodes, none >6 cm, ENE-
N3a	Any node >6 cm, ENE-
N3b	Any node with clinically overt ENE+

ENE = extranodal extension. Recognition of ENE as an upstaging factor is a key update in the 8th edition.

M (Distant Metastasis) Classification

M Category	Description
M0	No distant metastasis
M1	Distant metastasis present

Overall Stage Grouping

Stage	TNM
0	Tis, N0, M0
I	T1, N0, M0
II	T2, N0, M0
III	T1-2, N1, M0 or T3, N0/1, M0
IVa	T1-3, N2, M0 or T4a, N0/1/2, M0
IVb	T4b, any N, M0 or Any T, N3, M0
IVc	Any T, Any N, M1

(Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Table 7.3)

Historical Staging Reference: Ohngren's Line

Described in 1933, Ohngren's line is an imaginary plane from the medial canthus of the orbit to the angle of the mandible.

Infrastructural (antero-inferior to the line): earlier presentation, better prognosis, more amenable to complete resection
Suprastructural (superior and posterior to the line): later presentation, involves critical structures (orbit, skull base, carotid), poorer prognosis

This classification is now largely of historical interest given advances in craniofacial resection and radiation oncology (Scott-Brown's, Cummings Otolaryngology).

PART II: Investigations to Stage and Diagnose Maxillary Sinus SCC

A. Clinical Assessment

Full history - onset, nasal obstruction, epistaxis, facial pain/swelling, cheek numbness, diplopia, trismus, loose teeth, epiphora (each symptom maps to a specific direction of spread)
Head and neck examination
- Inspection: facial swelling/asymmetry, orbital proptosis, palate bulge
- Palpation: cervical lymphadenopathy (levels I-III are most relevant), cheek/infraorbital thickening
Cranial nerve examination - CN II, III, IV, V1, V2, VI palsy indicates advanced disease (orbital apex/cavernous sinus involvement)
Oral cavity examination - palatal bulge or ulceration, loose teeth, widened alveolar ridge

B. Endoscopic Evaluation

Rigid nasal endoscopy (0° and 30° telescopes)
- Mandatory in all suspected cases
- Assesses medial wall erosion, nasal cavity involvement, middle meatus extension
- Identifies polypoid/ulcerative mass, assesses accessible biopsy sites
- Note: outpatient biopsy may be non-diagnostic; tumour may show polypoid surface reaction

C. Imaging Investigations

Primary Imaging (Both Required Together)

Contrast-enhanced CT scan (axial + coronal reconstruction)
- Modality of choice for bony detail
- Assesses: bony erosion/destruction of antral walls, posterior wall, hard palate, pterygoid plates, orbital floor
- Detects: calcification, opacification, extent of bony involvement, skull base integrity
- Evaluates: sinus walls, lamina papyracea effacement, teeth/alveolar involvement
- Guides: surgical planning, custom prosthetic fabrication
Contrast-enhanced MRI (Gd-enhanced T1 + T2 + DWI sequences)
- Superior for soft tissue assessment
- Detects: dural/cerebral infiltration, orbital invasion, perineural spread
- T2 sequences: distinguishes retained secretions from active tumour
- Diffusion-weighted imaging (DWI): helps characterize lesion nature
- Gadolinium-enhanced images: show tumour vascularity (flow voids), dural enhancement
- 94-98% correlation with surgical findings

CT + MRI together are the standard - each is insufficient alone. (Scott-Brown's; Cummings Otolaryngology)

Additional Imaging

PET-CT (18-FDG)
- Role: detecting distant metastases in pretreatment staging
- Helps exclude occult metastatic disease and identify an unknown primary
- Limited by: 18-FDG uptake by sinonasal inflammation (confounds interpretation of primary)
- Useful in: posttreatment surveillance for recurrence
Chest X-ray / CT chest
- Screening for pulmonary metastases
- CT chest preferred for advanced (T3-T4) disease
CT/MRI of neck - for nodal staging (levels I-III principally)
Arteriography (selective, not routine)
- Only if pre-operative embolization is being considered for highly vascular tumours

D. Tissue Diagnosis

Biopsy - mandatory before any treatment
- Transnasal endoscopic biopsy (most common)
- Preferred under general anaesthesia - reduces non-diagnostic rate, allows biopsy from within sinus
- Caldwell-Luc approach should be avoided if it would seed tumour or compromise subsequent resection
- Facilities for haemorrhage control must be available (some sinus tumours are highly vascular)

E. Laboratory Investigations

Full blood count (FBC/CBC) - baseline haematological status
Liver function tests (LFTs) - hepatic metastases screening
Renal function tests - pre-treatment baseline (especially if chemotherapy planned)
Serum electrolytes and coagulation profile - pre-operative baseline
Alkaline phosphatase / bone profile - bone metastasis screen

F. Assessment Under General Anaesthesia (EUA)

Examination under anaesthesia (EUA) with endoscopy
- Allows thorough examination of the nasal cavity, nasopharynx, post-nasal space
- Enables representative deep biopsy from within the sinus
- Assesses full extent of visible tumour, palate, and nasopharyngeal involvement

G. Ophthalmological and Special Assessments

Formal ophthalmology assessment
- Baseline visual acuity, extraocular movements, visual fields
- Required when orbital involvement is suspected (guides decision on orbital exenteration)
Dental assessment/Orthopantomogram (OPG)
- Bone involvement of alveolus/dentition
- Pre-operative dental state for prosthetic planning
Audiometry - if Eustachian tube involvement is suspected (indicates advanced disease)
Neuroimaging/Neurosurgical consultation - if intracranial extension is suspected (T4b)

Summary: Investigations at a Glance

Category	Investigation
Clinical	Full history, head-neck exam, CN exam, oral exam
Endoscopic	Rigid nasal endoscopy (0°/30°)
Imaging	CT sinuses (bone), MRI (soft tissue), PET-CT (distant staging), CT chest
Tissue	Endoscopic biopsy ± EUA biopsy
Lab	FBC, LFT, RFT, electrolytes, coagulation, bone profile
Special	Ophthalmology, OPG, audiology, neurosurgical review

Sources:

Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Tables 7.2, 7.3 (AJCC TNM Classification)
Cummings Otolaryngology Head and Neck Surgery, Chapter 94 (Staging, Imaging, Biopsy, Workup)
K.J. Lee's Essential Otolaryngology, Rhinology chapter (Ohngren's line, treatment concepts)
Bailey & Love's Short Practice of Surgery, 28th Ed. (AJCC 8th edition staging principles)

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