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Neuroradiology Case of the Week

Case 160

Jared Christensen, MD and PL Westesson MD, DDS, PhD

Clinical Presentation: Patient is a 34-year-old male presenting with chronic, progressive congestion and intermittent headache.

Radiological Findings: The patient initially presented at an outside facility where a head CT was obtained - the images of which are not available. The MRI obtained for operative planning at our facility demonstrates a sinus mass of soft tissue signal characteristics filling the bilateral frontal sinuses, left greater than right (A), ethmoids, and extending into the left maxillary sinus (B & C). There is mild mass effect upon the left frontal lobe (A, arrowhead); however the brain parenchyma signal is unaltered at this level. The lesion enhances heterogeneously post contrast administration (C). Osseous remodeling with questionable disruption of the left frontal sinus posterior cortical wall was also identified.
     The patient subsequently underwent surgical resection. Intraoperative findings confirmed a large pedunculated polypoid mass extending from the frontal sinus, through the ethmoid cells and into the left maxillary sinus. Erosion of the posterior table of the frontal sinus with dural extension was identified.
     The patient presented several months post resection with recurrent symptoms and a non-contrast head CT was obtained (D). Post surgical changes are identified within the left frontal sinus and left nasal bone. The left middle meatus and medial wall of the left maxillary sinus are absent. A large soft tissue density within the left maxillary sinus is identified which extends within the left ethmoid sinus superomedially and into the left frontal sinus. The lesion is at least as large as the preoperative tumor.

Differential Diagnosis: Antrochoanal polyp; Sinonasal polyposis; Juvenile angiofibroma; Squamous cell carcinoma.

Diagnosis: Inverted papilloma with postoperative recurrence

Discussion:Inverting nasal papillomas are rare, benign but aggressive neoplasms of the nasal cavity and paranasal sinuses. The tumor most commonly arises from the lateral nasal wall in the middle meatus, but can originate from any sinus mucosa and routinely involves adjacent sinuses. Inverted nasal papillomas comprise 0.5 -7% of all nasal cavity tumors. Approximately 5-15% are associated with malignancy - usually squamous cell carcinoma, and less commonly adenocarcinoma - which may be synchronous or metachronous.
     Although the underlying etiology is not well-understood, nasal epithelial neoplastic transformation secondary to viral infection and smoking has been postulated. There is a 4:1 male to female predominance and peak incidence occurs between the 4th and 7th decades of life, although children and adolescents can also be affected. Patients typically present with unilateral nasal obstruction; other symptoms include epistaxis, sinusitis, anosmia, or facial pain.
     CT is the initial imaging modality of choice and coronal projections or reformats are essential. Common findings include a soft tissue mass along the lateral nasal wall originating from the middle meatus; the lesion may extend into the maxillary or ethmoid sinuses. Post contrast images demonstrate a variable pattern of enhancement. Inflammatory sinus disease may be seen if unilateral obstruction is present. Large lesions may exert mass effect on adjacent bone with remodeling or erosion. Approximately 10% of lesions calcify.
     CT is typically followed by MR for surgical planning. MR is most helpful in evaluating extra-sinonasal extension and in differentiating tumor from sinus secretions. Inverted papillomas as well as other tumors of the nasal cavity have low to intermediate T1 signal and intermediate to high T2 signal. The mass has a typical cerebriform appearance on T1 contrast imaging. Areas of necrosis and post-obstructive secretions demonstrate characteristic high signal.
     Surgical resection is recommended given the risk of associated malignancy and expected progressive worsening of symptoms. Procedures are commonly performed endoscopically with a standard approach which includes medial maxillectomy through a lateral rhinotomy with en-bloc excision. Inverted papillomas have a high local recurrence rate (20%) if incompletely resected, as illustrated by this case presentation.

References:

1. Harnsberger HR, et al. Diagnostic Imaging: Head and Neck. W.B. Saunders, 2004; 68-71.
2. Dammann F, Pereira P, Laniado M, Plinkert P, Lowenheim H, Claussen CD: Inverted papilloma of the nasal cavity and the paranasal sinuses: using CT for the primary diagnosis and follow-up. AJR Am J Roentgenol. 1999 Feb;172(2):543-8. [Medline]