Unusual paranasal sinus solitary neurofibroma and literature review

Neurofibroma (NF) is a common benign peripheral neurogenic tumor that is rarely encountered in the paranasal sinus tract. In this report, we present a 55-year-old female who serendipitously discovered a maxillary sinus NF during a medical examination for a pulmonary nodule. The purpose of this article is to enhance medical practitioners' comprehension of paranasal sinus solitary NF by exploring cases, summarizing occurrences located in the paranasal sinus tract and conducting an organized review of paranasal sinus tract NF.

diagnostics, the nasal sinus mass was thought to be benign.A dialogue with the patient regarding further management ensued, eventually resulting in her consent for priority surgery of maxillary sinus masses.Postoperative complications were not observed.The patient was discharged ten days after surgery.An MRI scan conducted five months post-surgery revealed no recurrence.For the treatment of lung cancer, the patient underwent gene detection and targeted chemotherapy successively; however, the latest follow-up displayed lacklustre efficacy and CT displayed metastases of liver, lung and spine.

pathoLogiCaL FinDings
Since the nasal sinus mass may have been benign, endoscopic resection of the left maxillary sinus mass was performed immediately; pathological results indicated paranasal sinus tract neurofibroma (NF) (Figure 3).

DisCUssion
NF is a common benign neurogenic tumor, which rarely occurs in the paranasal sinus. 1 So far, fewer than 100 cases have been reported in the literature around the world, mostly as individual case reports.It is mainly seen in individuals between 10 and 70 years old, with a peak age of onset at 30 years old; it is slightly more common in females than males. 2,3Most paranasal sinus NFs are primary solitary lesions (90%), with only a few related to type I neurofibrosis (10%). 4,5case of paranasal sinus NF in the maxillary sinus is reported here.Although she has lung adenocarcinoma with cervical lymph node metastasis, there is no evidence of association among them.
Clinical manifestations of sinus NF lack specificity and vary depending on location.Common clinical manifestations include local swelling, pain, nasal congestion or runny nose as well as epistaxis or facial discomfort; occasionally invading the orbit can lead to exophthalmos and visual impairment, 4 invading alveolar bone can lead to tooth loosening or abnormal occlusion, 2 and invading brain tissue can cause headaches. 17Solitary NFs differ from NF1 related ones due to lack of common skin coffee spots or family history associated with them. 5e imaging findings for paranasal sinus NFs show nonspecific changes but understanding certain characteristics may help prompt diagnosis: (1) Paranasal sinus NFs is most commonly found in maxillary sinuses followed by frontal ones while ethmoid and sphenoid are rarer; out of 20 cases summarised here 13 were located in maxillary while four were located at frontal ones and one at ethmoid; other cases involved both ethmoid and sphenoid but all part of nasal NF. (2) Paranasal sinus NFs are more commonly seen as solitary lesions than NF1-related ones; only 3 of 16 cases (18.75%) being NF1related.Whereas 90% being solitary lesions according to Azani et al, 3 which was consistent with our findings.NF1-associated tumors often present multiple lesions involving multiple sites simultaneously.(3) On X-ray paranasal sinus, NFs usually manifest by decreased transparency within affected area sometimes accompanied by dilated Sinuses.Whereas CT usually shows heterogeneous solid mass inside nasal cavity, sometimes cystic too, when small tumor size does not change size within affected area; however, large tumors may expand said cavity or even cause local bone absorption/breakage through its walls into orbital/intracranial/pterygomaxillary fossa areas, respectively; contrast enhancement showed mild up to obvious enhancement which may be linked toward tissue components within said tumor. 12,18While MRI showed medium low signal on T1WI, heterogeneous medium signal/high signal on T2WI, without limited diffusion on DWI. 18(4) Despite invasive nature potentially leading up toward malignant NF recurrence after surgical resection almost non-existent. 12,19

DiFFeRentiaL Diagnosis
The differential diagnosis of paranasal sinus NFs includes cysts, schwannomas, solitary fibroid tumors, inflammatory pseudotumors, fungal granulomas, inverted papillomas, ectopic meningiomas, ossifying fibroids, leiomyosarcomas, lymphomas, metastasis and so on.If low density or cystic components are found inside the tumor, maxillary sinus cysts/ schwannomas should be differentiated.When solid tumors with delayed enhancement are manifested, solitary fibromas, inflammatory pseudotumors, fungal granulomas, inverted papillomas, and ectopic meningiomas need be distinguished, while calcification is detected, ossifying fibromas would be differentiated first.Once bone walls and surrounding tissues are invaded, leiomyosarcoma, lymphoma, and metastatic tumor should be identified.tReatMent Surgery is currently the main treatment option for paranasal sinus NFs.Although slow progression and good prognosis are common, radiotherapy and chemotherapy may be performed while malignant lesions are detected. 18 conclusion, paranasal sinus NFs is a rare benign neurogenic neoplasms, which expressed either isolation or NF1 correlation.Despite there is non-specific in-clinical presentation and imaging features of it, consideration should be given to the possibility of paranasal sinus NFs when diagnosed benign masses and solid tumors of the paranasal sinus by imaging, especially in those with NF1.

LeaRning points
1. Paranasal sinus solitary NFs are a rare type of tumor mainly occurring within the maxillary sinuses.

patient Consent
Written informed consent for the case to be published (incl.images, case history and data) were obtained from the patients for publication of this case report, including the accompanying images.

ethiCs appRovaL
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.All involved patients signed an informed consent form.

Figure 1 .
Figure 1.Transverse MR imaging of the nasal sinus demonstrated a solid mass occupying her left maxillary sinus(white arrows), measuring approximately 45 mm × 36 mm × 26 mm, and exhibiting hypointensity on T1WI(a), inhomogeneous hyperintensity on T2WI(b) and fat-suppression sequence(c), and moderate hyperintensity on DWI(d).

Figure 2 .
Figure 2. Axial non contrast-enhanced CT imaging(a) showed a round solid soft tissue mass(white arrows) in the left maxillary sinus with punctate calcification at its center(black arrow head).Contrast enhanced CT imaging(c and d) indicated mild uneven enhancement of the mass (an increase of about 5-10 HU); her maxillary sinus cavity was distended with bone resorption on its inner wall(d).