Olfactory neuroblastoma, esthesioneuroblastoma, esthesioneuroepithelioma

Epidemiology

Olfactory neuroblastoma accounts for 1% to 5% of malignant nasal cavity neoplasms.

Clinical features

These tumours arise across a broad age range with a bimodal peak in the second and sixth decades of life. Tumour arise in the olfactory membrane of the upper nasal cavity.

Histopathology

Tumours comprise small to medium size cells with pale eosinophilic cytoplasm. Nuclei are round with fine chromatin and without conspicuous nucleoli. The cells form well-defined nests of cells embedded in a fibrous stroma. There may be a prominent capillary network. The tumour cells form rosettes, at least focally. There may be foci of squamous or glandular differentiation. Rarely, there is maturation to ganglioneuroblastoma.

Immunohistochemistry

Calretinin	20/212
NSE	positive
S-100	variable: positive in spindle cells at periphery of nests
cytokeratin	20-25% of cases1, mainly in foci of squamous or glandular differentiation
GFAP	variable
neurofilament protein	variable
chromogranin	variable
synaptophysin	variable
CD56	variable
Leu-7	variable
EMA	negative
CEA	negative
LCA	negative
HMB-45	negative
CD99	negative
desmin	negative
p63	0/212

Ultrastructure

There are numerous neuroendocrine granules and neural cell processes.

Differential diagnosis

Typical immunohistochemical staining profile for Small Round Blue Cell Tumours of the sinonasal tract

sinonasal small cell neuroendocrine carcinoma; there is a high mitotic rate and necrosis is prominent. Neurofibrillary stroma an S-100 positive cells are lacking. There may be diffuse cytokeratin positivity.
sinonasal undifferentiated carcinoma (SNUC)
non-keratinising nasopharyngeal carcinoma
alveolar rhabdomyosarcoma: negative for neuroendocrine markers and S-100 but positive for desmin and actin.
melanoma, small cell variant: show more pleomorphism and are negative for neuroendocrine markers but diffusely positive for S-100.
teratocarcinosarcoma
pituitary adenoma: express cytokeratins and specific pituitary hormones.
lymphoma
Ewing sarcoma / PNET

Management

Treatment is usually a combination of surgery and radiation.

Prognosis

30% to 70% of patients will experience local recurrence, 20% to 40% will experience cervical lymph node metastasis, and 10% will experience distant metastasis. The most common sites of metastasis are the lymph nodes, lungs, and bone. The five-year survival rate correlates with clinical staging and ranges from 75% for tumour confined to the nasal cavity to 41% for tumour extending beyond the sinonasal cavities. Distant metastases may occur years after the initial diagnosis2. While prognosis depends on the clinical stage but is often unpredictable. Longer disease-free survival is associated with:

increased number of S-100 positive cells.
a Ki-67 proliferation index below 10%

References

Diagnostic histopathology of tumors. Edited by CDM Fletcher. 2nd edition. Churchill Livingstone. Page 113.

1 Perez-Ordonex B. Special tumours of the head and neck. Current Diagnostic Pathology 2003;9:366-383.

2 Wooff JC, Weinreb I, Perez-Ordonez B, Magee JF, Bullock MJ. Calretinin staining facilitates differentiation of olfactory neuroblastoma from other small round blue cell tumors in the sinonasal tract. Am J Surg Pathol. 2011 Dec;35(12):1786-93.

This page last revised 6.3.2012.