Esthesioneuroblastoma

Introduction:

This tumor arises from the olfactory nerve. These are rare malignant tumors arising from the olfactory epithelium situated at the roof of the nasal cavity, cribriform plate, upper portion of supeior turbinate and corresponding upper portion of nasal septum. These tumors typically involve the upper portion of nasal cavity and the cribriform plate area. These tumors classically arise from the basal cells of olfactory neuroepithelium. No clearl cut genetic / other causes have been attributed for this tumor. This tumor represents about 3% of all malignant tumors involving the nasal cavity.

This tumor was first reported by Berger etal in 1924. Since then only less than 1000 cases have been reported in literature.

Incidence:

Affects both male and female patients with equal frequency.

Age incidence shows a bimodal peak (peaking at the second and the sixth decades of life).

Etiopathogenesis (theories):

1. Belongs to peripheral neuroectodermal family. (Not supported by immunohistochemistry)
2. Presence of Trisomy 8 has been documented in these tumor cells

None of these theories convincingly explain etiopathogenesis of this tumor.

Clinical features:

This tumor classically involves the nasal cavity with extension into the ethmoid sinus, anterior skull base and orbit. Since these tumors are very aggressive ones they tend to metastasize extensively. Spread to cervical nodes are common. Retropharyngeal nodes are the first echelon node. Rarely these tumors may be active in an endocrine sense. These tumors have known to cause ectopic secretion of ACTH causing Cushing's syndrome.

Common presenting symptoms were usually associated with the nasal cavity:

1. Nasal block
2. Epistaxis
3. Anosmia

Staging system:

Staging a tumor helps in deciding the optimal management modality and also in determining the prognosis of the disease.

Kadish staging system:

This system stages Esthesioneuroblastoma into three stages:

Stage A: Tumor limited to nasal cavity

Stage B: Tumor extending to paranasal sinuses

Stage C: Tumor extending beyond paranasal sinuses

Major inadequacy of this staging system is too broad a staging at the level of Stage C.

Modified TNM staging system:

Tumor

T1 – tumor involving nasal cavity and / or paranasal sinuses (excluding sphenoid) sparing most of the superior ethmoidal cells

T2- tumor involving nasal cavity and / or paranasal sinuses including sphenoid with extension to the cribriform plate

T3 – tumor extending to orbit with involvement of extradural anterior cranial fossa

T4 – tumor involving brain

Node

N0 – No nodal metastasis

N1 – any form of nodal metastasis

Metastasis

M0 – No metastasis

M1 – Metastasis present

Hyam came out with a histopathological grading system which turned out to be more accurate than the preceding two staging systems.

Hyam's Histopathological grading system

Grade	LA preservation	Mitotic index	Nuclear polymorphism	Fibrillary matrix	Rosettes	Necrosis
I	+	Zero	None	Prominent	HW	None
II	+	Low	Low	Present	HW	None
III	+/-	Moderate	Moderate	Low	FW	Rare
IV	+/-	High	High	Absent	None	Frequent

Fw – Flexner-wintersteiner

HW – Homer – Wright

Management:

This tumor is managed with wide surgical resection with adequate tumor margins. Radiotherapy is indieated as primary treatment modality in unresectable tumors and as a follow up to surgical debulking.