Benign tumor

Retention cyst: A retention cyst is a fluid-filled, slowly expansile mass arising from the paranasal mucous membranes that can be found in up to 10% of all adults (Fig. 13.9a). Most retention cysts remain clinically silent. They can occasionally erode bone. The cysts may grow out of the maxillary sinus through the ostiomeatal complex and become clinically apparent as choanal polyps. Osteoma: This benign bone tumor tends to occur in the frontal sinus (Fig. 13.9b). The high density of the round or lobulated tumor on the radiograph makes this an easy and definite diagnosis.

Juvenile angiofibroma: Male adolescents may develop a juvenile angiofibroma (Fig. 13.9c). This arises in the pterygopalatine fossa and extends into the nasopharynx and can obliterate the sinus. Surgeons prefer embolization of this very vascular tumor prior to resection.

Malignant tumor: If conservative therapy fails or if there is radiographic evidence for osseous destruction (Fig. 13.10a), malignant processes need to be considered. To properly evaluate the extent of the tumor, the potential infiltration of vessels, nerves, muscles, and parotid glands as well as the lymph node status for subsequent therapy, MRI is the modality of choice (Fig. 13.10b). CT (with 3D reconstructions) is excellent for assessment of osseous structures and operative planning but lacks the superior contrast resolution for soft tissue structures that MRI has to offer.

• Diagnosis: Hannah thinks that chronic sinusitis is the most likely diagnosis. Paul is bothered by the fact that Mr. Cavern has never had problems with his sinuses in the past. They are still discussing as Gregory happens to drop by on his way to the neurointervention suite. He observes that the nasal septum is destroyed and is also alerted by clinical history and the age of the patient:

"This is an aggressive process until proven otherwise, kiddos. Think cancer!" Hannah reluctantly agrees—she simply did not analyze the image with sufficient care. At a second glance it seems so obvious. This won't happen to her again. The histological diagnosis a week later comes back from the laboratory as squamous cell carcinoma.

f Four eyes see more than two. To ask someone with more i experience for help is not a sign of weakness... on the contrary it is quite smart. For experienced radiologists it is an honor to help the neophyte—they tend to feel tickled—and you as the neophyte profit from it. But be warned: Radiology is a complex field. "Old hands" may also miss a thing or two—and they know it.

I Chronic Sinusitis

I Chronic Sinusitis

Sinusitis Frontal Waters View
Fig. 13.8 This Waters view illustrates the sclerosis of the bone and volume loss in both maxillary sinuses in a patient with chronic sinusitis. The left frontal sinus is opacified; the right one is not seen at all.

I Benign

Tumor a Retention cyst a Retention cyst

Frontal Sinus CystJuvenile Retention Polyp

c Juvenile angiofibroma b Osteoma c Juvenile angiofibroma b Osteoma

Benign Tumors

Fig. 13.9a The anterior-posterior radiograph of the skull (left) documents an expansion of the right frontal sinus with sclerotic margins. The orbital roof is depressed; the left frontal sinus is obliterated. The axial CT image (right) confirms expansion of the right frontal sinus and shows an impressive deviation of the septum to the left. The cause of this is a retention cyst. b A coronal CT section displays a round body of osseous density and structure in the frontal sinus, probably extending from the roof of the sinus. It is a typical osteoma. c The axial T1-weighted MR image obtained after contrast administration documents a large, nodular mass in the dorsal roof of the nasopharynx. This appearance, together with the clinical findings, is compatible with the diagnosis of a juvenile angio-fibroma.

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