**9. Neoplasms**

Osteoma is one of the most common benign neoplasms in the paranasal sinuses (**Figure 15a** and **b**), followed by fibrous dysplasia (**Figure 16a**–**c**) and inverted papillomas (IP) (**Figure 17a**–**c**).

**Figure 15.** *(a) Sagittal and (b) axial CT of an osteoma in the frontal sinus. Unless obstruction of the mucociliary drainage, osteomas have no clinical impact.*

#### **Figure 16.**

*(a) Coronal CT and (b) axial CT demonstrate fibrous dysplasia, in the right sphenoid bone. The bone has characteristic "ground glass" appearance and encircles the foramen rotundum and the Vidian canal. In addition, the sphenoethmoid recess is obstructed and mucus entrapped in the right sphenoid sinus, with bowing of the sinus walls typical for mucocele and pyocele. (c) Axial MRI with T1 with gadolinium shows contrast medium enhancement limited to the mucosal lining. The low signal in the sinus is consistent with a mucocele.*

**21**

**Figure 17.**

**Figure 18.**

postulated as a cause [22].

*must always be ruled out.*

IP is reported to be up to 5% of sinonasal tumors. Age group affected is 40–70 years, with a male preponderance. IP derives from the respiratory mucosa. The characteristic growth pattern with mucosal infoldings into the stroma is the origin to the name inverted. In most cases IP originates from the ethmoid sinuses and middle meatus [21]. Etiology is not confirmed, but a viral infection has been

*neuroblastoma. (b) Coronal CT shows a polyp in the left nasal cavity, where histology revealed acinic cell carcinoma, which is a malignant salivary gland tumor. Malignancy in solitary polyps in the nasal cavity* 

*(a) Coronal CT shows a tiny polyp in the right nasal cavity. Histopathology revealed olfactory* 

*(a) Coronal, (b) axial, and (c) sagittal CT of an inverted papilloma originating from the ethmoid sinus and filling the middle part of the nasal cavity and choana. The site of origin often shows hyperkeratosis. In this case* 

*the origin could be from beneath the ethmoid cells that shows slight keratosis at the sagittal CT.*

*Imaging in Sinonasal Disorders*

*DOI: http://dx.doi.org/10.5772/intechopen.90773*

**Figure 17.**

*Sino-Nasal and Olfactory System Disorders*

papillomas (IP) (**Figure 17a**–**c**).

*drainage, osteomas have no clinical impact.*

**9. Neoplasms**

**Figure 15.**

MRI findings that may indicate poor prognosis [19]. Sinonasal surgery in GPA is

Osteoma is one of the most common benign neoplasms in the paranasal sinuses (**Figure 15a** and **b**), followed by fibrous dysplasia (**Figure 16a**–**c**) and inverted

*(a) Sagittal and (b) axial CT of an osteoma in the frontal sinus. Unless obstruction of the mucociliary* 

*(a) Coronal CT and (b) axial CT demonstrate fibrous dysplasia, in the right sphenoid bone. The bone has characteristic "ground glass" appearance and encircles the foramen rotundum and the Vidian canal. In addition, the sphenoethmoid recess is obstructed and mucus entrapped in the right sphenoid sinus, with bowing of the sinus walls typical for mucocele and pyocele. (c) Axial MRI with T1 with gadolinium shows contrast medium enhancement limited to the mucosal lining. The low signal in the sinus is consistent with a mucocele.*

debated [20] and may cause increased osteoneogenesis (**Figure 14a**–**c**).

**20**

**Figure 16.**

*(a) Coronal, (b) axial, and (c) sagittal CT of an inverted papilloma originating from the ethmoid sinus and filling the middle part of the nasal cavity and choana. The site of origin often shows hyperkeratosis. In this case the origin could be from beneath the ethmoid cells that shows slight keratosis at the sagittal CT.*

#### **Figure 18.**

*(a) Coronal CT shows a tiny polyp in the right nasal cavity. Histopathology revealed olfactory neuroblastoma. (b) Coronal CT shows a polyp in the left nasal cavity, where histology revealed acinic cell carcinoma, which is a malignant salivary gland tumor. Malignancy in solitary polyps in the nasal cavity must always be ruled out.*

IP is reported to be up to 5% of sinonasal tumors. Age group affected is 40–70 years, with a male preponderance. IP derives from the respiratory mucosa. The characteristic growth pattern with mucosal infoldings into the stroma is the origin to the name inverted. In most cases IP originates from the ethmoid sinuses and middle meatus [21]. Etiology is not confirmed, but a viral infection has been postulated as a cause [22].

Though initially benign, the recurrence rate is up to 25%, and malignant transformation is common, especially in smokers.

IP may display characteristic hyperkeratosis at CT from where the IP origin in the sinus wall. Radiological reporting of the attachment site is important for complete surgical resection [23] (**Figure 17a**–**c**).

Malignant sinonasal tumors are rare, and squamous cell carcinomas are the most common (80%). Rarer malignant sinonasal neoplasms are adenocarcinoma, olfactory neuroblastoma (**Figure 18a**), salivary gland tumors (**Figure 18b**), chondrosarcoma, B- and T-cell lymphoma, and mucosal malignant melanoma.

Juvenile nasopharyngeal angiofibroma is a benign tumor in adolescent males that arises from testosterone-sensitive cells in the pterygoid plates [24].
