Radiological Diagnosis

Esthesioneuroblastoma with Intracranial Marginal Cysts.

CT shows a large paranasal sinus and nasal cavity mass that extends into the anterior cranial fossa. The lesion has eroded into the frontal, ethmoid and the sphenoid sinuses with extension into both orbits. The intracranial component of the mass is seen on either side of the falx cerebri with multiple large peripheral cysts along the tumor margin. Fluid levels are also seen in these cysts.

Esthesioneuroblastoma (ENB) is a specific type of malignant neuroectodermal tumor that arises from the bipolar sensory receptor cells [1] in the olfactory mucosa and rarely in the region of the middle turbinates and adjacent paranasal sinuses [2]. ENBs generally demonstrate a fairly consistent pattern in CT. They are usually iso to hyperdense with moderate contrast enhancement [3]. Calcification has been reported both histologically [4] and radiologically [5]. Bony destruction with extension of the tumor beyond the paranasal sinuses particularly involving the orbits and the anterior cranial fossa through the cribriform plate is quite common. All the features are not unique to ENB. They can be seen in many of the undifferentiated small cell tumors like anaplastic carcinoma, lymphoma, extra medullary plasmacytoma and amelanotic melanoma of the paranasal sinuses. But till date none of these tumors have been reported to have marginal cysts. Tumoral cysts at the margins of intracranial extension have been reported only in ENB [6]. The tissue composing the walls of these marginal cysts are arachnoid and tumor [6]. The precise reason for the association of arachnoid cyst adjacent to an intracranial mass is not known. Marginal cysts may be identified with other lesions; however, the only known sinonasal tumor to be associated with such cysts is ENB. Thus the presumptive diagnosis of ENB can be made based on these imaging criteria, with a very high degree of reliability.