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Neuroradiology Case of the Week

Case 300

Scott Rudzinski, Ben Wandtke, MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A 32-year-old female presented with a history of right nasal mass and recurrent epistaxis.

Imaging Findings: There is a large expansile mass centered in the right ethmoid air cells and right nasal cavity. It involves and destroys the cribiform plate and right ethmoid air cells. It is predominantly intermediate signal on T2 weighted images with focal cystic change superiorly along the frontal lobe interface. It demonstrates intermediate signal on T1 weighted images with prominent post-contrast enhancement. The mass uplifts the dura and extends into the anterior cranial fossa exerting mass effect upon the inferior frontal lobes.
     There is complete filling of the right maxillary sinus with mucosal thickening and retained secretions likely due to occlusion of the ostiomeatal complex. There is also mucosal thickening and fluid in the frontal sinuses also likely due to obstruction from the mass.

Diagnosis: Esthesioneuroblastoma

Discussion: Esthesioneuroblastoma (ENB), also called olfactory neuroblastoma, is a rare malignant neuroendocrine neoplasm of the nasal vault believed to arise from olfactory epithelium. ENB represents about 2-5% of all malignant nasal tumors and occurs in a wide range (3-90 years), with a bimodal peak in the second and sixth decades of life, with a slight female predominance.
     Histologically the tumor contains epithelial nests of small round cells and small short spindle cells surrounded by a net of fibrous connective tissue and rosette or pseudorosette formation. Immuno-histochemistry for neural or neuroendocrine markers is essential for diagnoses. Pathologically ENB may be confused with anaplastic carcinoma, large cell lymphoma, melanoma, extramedullary plasmcytoma, embryonal rhabdosarcoma or other sarcomas.
     The most common presenting symptoms are unilateral nasal obstruction, recurrent epistaxis, and anosmia. Less commonly these tumors may present with ocular disturbances and headaches. On rhinoscopic exam ENB presents as a mass that may be indistinguishable from polyposis, chronic sinusitis or other nasal malignancies. The average time of diagnoses from the development of first symptoms is 6 months. Clinicians must use caution during biopsy, as profuse bleeding occurs with ENB.
     The classic appearance of ENB is a dumbbell mass extending superiorly to the intracranial fossa and inferiorly to the upper nasal cavity with the “waist” at the level of cribiform plate. Important associated imaging characteristics include cystic change along the superior tumor margins especially within the anterior cranial fossa and calcifications with the mass. Appropriate evaluation includes CT and MRI with coronal sections. Thin section maxillofacial CT scan with coronal reconstruction is the initial radiologic study of choice. CT may show bone remodeling causing enlargement of the nasal cavity mixed with bone destruction. ENB is a homogeneously enhancing mass on CT. On T1 MR the mass in hypointense to isointense to brain parenchyma and on T2 MR is intermediate to hyperintense to brain parenchyma. Characteristic cystic change can be seen along the superior margins on coronal T2 images. MR enables a better estimate of tumor spread into surrounding soft tissue and can differentiate sinus disease secondary to outflow obstruction from the tumor itself. When ENB is suspected the anterior cranial fossa, sinonasal area and cervical neck should all be scanned because 5-20% of ENB show cervical lymph node metastasis upon initial presentation. Local recurrence has been reported in slightly more than 50% of patients and recommended post treatment follow-up includes MR with contrast every 4-6 months for 5 years and then annually for the patient’s lifetime.
     Important differentials include extracranial nasal meningioma, squamous cell carcinoma (SCC) of the nose, non-Hodgkin's lymphoma (NHL) of the nose and sinonasal undifferentiated carcinoma (SNUC). Extracranial nasal meningioma in not associated with cyst formation. SCC may be indistinguishable from ENB when it arises high in the nasal vault, although SCC is more common in the maxillary antrum than the nasal cavity and does not enhance as avidly as ENB. NHL also does not enhance to the same degree as ENB and rarely breaches the skull base. SNUC presents similarly to ENB and may be indistinguishable.

     Radiologic staging described by Dulguervo and Allal is as follows:

     The treatment of choice is a combination of surgery and radiotherapy. Prognosis depends on tumor staging. Kadish, et al. described a prognostically valuable staging (A-D), with low grades having a greater than 90% three year survival, and high grades having a less than 40% survival.

References:

1. Bradley PJ, Jones NS, Robertson I. Diagnosis and management of esthesioneuroblastoma. Curr Opin Otolaryngol Head Neck Surg. 2003 Apr;11(2):112-8. [Medline]
2. Das S, Kirsch CF. Imaging of lumps and bumps of the nose: a review of sinonasal tumours. Cancer Imaging. 2005 Dec 9;5:167-77. [Medline]
3. Harnsberger HR. Diagnostic Imaging: Head and Neck. Amirsys, UT. 2004.
4. Dulguervo P, Allal AS. Esthesioneuroblastoma. eMedicine.com, August 11, 2006. http://www.emedicine.com/med/topic748.htm
5. Kadish S, Goodman M, Wang CC: Olfactory neuroblastoma. A clinical analysis of 17 cases. Cancer 1976 Mar; 37(3): 1571-6. [Medline].