Teaching Case

54 years old previously healthy male came with complaints of nasal blockage (right side), occasional subtle bleeding from right nostril and headache since few days. No history of any comorbidities or trauma. On examination, polypoidal solid mass lesion was found within right nasal cavity and Partial loss of smell sensations.

Physician suspected benign nasal polyp and advised for CT and MRI of Brain and Paranasal sinuses.
Plain MRI shows heterogeneously T1W and T2W Hypointense and FLAIR Hyperintense solid mass lesion within right nasal cavity, right sided ethmoidal sinuses and entire sphenoid sinus causing subtle destruction of ethmoidal bony septa and thinning of bony walls and displacing nasal septum to left side. Fluid retention within right maxillary sinus (secondary to maxillary infundibulum stenosis). This mass lesion appears to be heterogeneously hyperdense on Plain CT scan. Subtle restricted diffusion is seen within this lesion. Subtle T2W hypointense soft tissue component is identified within basifrontal cortex just above cribriform plates (shown in sagital T2W images). In post contrast study, this mass lesion shows heterogeneous and avid enhancement with enhancing basifrontal soft tissue component. Tiny nonenhancing cyst is seen within basifrontal soft tissue component.
Based on this imaging findings , we suspected Invasive fungal sinusitis.

Patient was put on Antifungal medicines for few days, but did not show any symptomatic improvement. Then we took tissue biopsy and sent for microbiological and histopathological analysis. In histopathological analysis it turned out to be Olfactory Neuroblastoma. Complete Surgical excision of this mass lesion was performed without any post operative complication.

Olfactory neuroblastoma (esthesioneuroblastoma), is rare malignant tumor of neural crest cell origin, arising from the olfactory epithelium of the upper nasal cavity. It accounts only 2 to 5 percent of all nasal tumours. It is seen generally in adulthood and older age groups with bimodal distribution. [1, 2] Accurate Staging of the disease at the initial presentation is most essential to predict survival and prognosis.[1] Nowadays, T.N.M Staging system is used stating tumour size and extent, nodal and distant metastasis. [1, 2]
Olfactory Neuroblastoma presents with epistaxis, nasal blockage, decreased or loss of olfactory function, diplopia, proptosis , headache.[1, 2] Local spread of tumour is seen into adjacent paranasal sinuses, orbits and anterior cranial fossa with brain involvement. Metastatic spread is generally by lymphatic or hematogenous routes with most frequently to cervical lymph nodes followed by distant metastasis to Lung, Liver , bones. [1, 2]
Imaging modalities such as CT and MRI are the gold standard to detect presence, extent and regional spread of tumour. CT is more useful in defining adjacent bony destruction or remodelling involving ethmoidal septa, cribriform plates , orbital walls. [1, 2] It is also useful in assesement of intralesional calcifications and cervical lymphadenopathy.
Typical CT findings include heterogenously hypo or hyperdense soft tissue mass lesion within right nasal cavity showing intralesional contrast enhancement.[1, 2] MRI is also superior in defining the soft tissue extent of tumour and gives more accurate assessment of suspected intracranial, orbital, or skull base infiltration and perineural spread of tumor. Entrapped sinus chronic secretions can be differentiated from neoplastic lesion by MRI more accurately (Entrapped secretions appear hyperintense on T2W image and non enhancing). Intralesional calcification and presence of cysts along with intracranial margins in case of intracranial extension of tumour is a characteristic feature.[1, 2] Typical MRI findings include T1W hypointense and T2W, FLAIR Hyperintense or hypointense solid mass lesion within nasal cavity. On contrast study, it shows avid enhancement.
Craniofacial surgical resection with adjuvant chemothrapy or radiotherapy is treatment of choice with 5 years survival rate of about 70 percent.[2]
‘Written informed patient consent for publication has been obtained.’