Inverted papilloma is found in the middle nasal tract region in the lateral wall of the nasal cavity, with the septal and maxillary sinuses being the most susceptible, and has a tendency to recur and become malignant. Previously, the external nasal approach (lateral nasal dissection, nasal reversal, etc.) was considered the routine procedure for the treatment of nasal invagination papilloma. It has been gradually replaced by nasal endoscopic surgery for more than two decades. From January 2002 to December 2010, we performed nasal endoscopic maxillary sinus (enlargement) lumpectomy on 23 cases of nasal invasive papilloma invading the septal and maxillary sinuses with complete resection and satisfactory results. The results are reported as follows. 1. Clinical data and methods 1. 1 General data There were 23 cases in this group, 18 males and 5 females. The age was 24-68 years old, with an average of 47.2 years old. The main symptoms in order were nasal congestion in 23 cases, accompanied by aspirated blood in 3 cases, loss of smell in 6 cases, headache in 2 cases, and toothache in 1 case. The tumors were papillary in appearance in 21 cases, polyp-like in 1 case and lobulated in 1 case. The tumors were located in the left side of the nasal cavity and sinuses in 17 cases and in the right side in 6 cases, but there were no cases of bilateral disease. Among them, there were 12 cases with bone destruction, 6 cases in the medial wall of maxillary sinus, 2 cases in the posterior external wall, and 4 cases in the septal sinus with bone septum destruction. According to the Krouse grading system [6], there were 16 cases in stage II, 9 cases invading the nasal cavity, the upper wall of the maxillary sinus and the anterior group of septal sinuses, 7 cases invading the nasal cavity, the inner wall of the maxillary sinus and the anterior and posterior group of septal sinuses; 7 cases in stage III, 2 cases invading the nasal cavity, the anterior group of septal sinuses, the inner anterior wall of the maxillary sinus, 2 cases invading the nasal cavity, the anterior group of septal sinuses, the inner and outer wall of the maxillary sinus, 1 case invading the nasal cavity, the anterior group of septal sinuses and the inner base wall of the maxillary sinus. One case invaded the frontal crypt and one case invaded the pterygoid sinus. The diagnosis was confirmed by pathological examination before surgery, and three cases were associated with moderate atypical hyperplasia. 1.2 Surgical methods: All surgeries were performed under general anesthesia with tracheal intubation or laryngeal mask and controlled intraoperative hypotension. Main surgical instruments: Medtronic electric cutting suction device with suction electrocoagulator, long-handled electric knife, long-handled electric drill, with suction stripper, 360o rotating, straight or angled biting forceps, medullary nucleus forceps, angled scraping spoon, round and flat chisel and dovetail chisel, 0o, 30o, 70o nasal endoscope, etc. 1,2,1 For Krouse stage II tumor, total septal sinus resection + maxillary sinus opening enlargement: carefully remove all tumor tissues with careful localization of the paper plate, orbital floor and anterior skull base. The maxillary sinus opening area was enlarged posteriorly and downward as much as possible using 360o rotating, straight or angled occlusal forceps. The trauma was charred by electrocoagulation and the bone roughness was polished by electric drill. 1,2,2 When the tumor invades the inferior turbinate, add nasal endoscopic resection of the inner wall of the maxillary sinus: from the anterior attachment of the middle turbinate, cut the mucoperiosteum obliquely downward along the maxillary crest to reach the anterior part of the inferior turbinate with a hooked knife, separate it downward, and cut the nasolacrimal duct after breaking the bone with a round or flat chisel. The outer wall of the nasal cavity was pried open and displaced inward, and then the outer wall of the nasal cavity was cut along the level of the nasal floor, and the posterior ends of the middle and inferior turbinates were broken, and the outer wall of the inferior nasal cavity was removed in a series of pincer cuts. At this time, the medial part of the maxillary sinus is better exposed, and the tumor tissue in the maxillary sinus can be removed using a 30o or 70o scope with an elbow cutter, curved forceps or scrapers. 1,2,3 For Krouse stage III tumor invading the lateral, anterior and basal walls of maxillary sinus, expanded medial maxillary sinus resection can be added: that is, on the basis of the medial maxillary sinus resection, the medial part of the anterior maxillary sinus wall, including the nasal bone on the side of the lesion, the frontal process of maxilla, and the outer edge of the pyriform foramen, can be removed in an arc after subcutaneous subperiosteal separation. The infraorbital neurovascular bundle was preserved to reduce postoperative facial swelling. At this time, a fixable anterior nasal mirror or a pulling hook was used to open the anterior nostril and 0o or 30o mirror was used to treat the diseased tissue of each wall of the maxillary sinus. 2. Results All 23 cases were completely resected under nasal endoscopy. Intraoperative bleeding ranged from 200 to 600 ml, and only one case had a transfusion of 400 ml. operative time ranged from 60 to 150 min, with a mean of 118 min. after the operation, the cavity was filled with Sorbalgon’s expansion sponge coated with erythromycin ointment after electrocoagulation of the trabecular margin, and removed after 1-2 days, with no There was no active bleeding. The postoperative facial swelling disappeared after 2 days. Postoperative saline irrigation and weekly endoscopic cleaning of the surgical cavity scab were completed with epithelialization within 3 months. The average follow-up was 48 months, 12-96 months; only 3 cases recurred after 1 year after surgery, with a recurrence rate of 13%. The site of recurrence was in the frontal saphenous area, which was resected again endoscopically, and there was no recurrence at 15 months of follow-up. The postoperative pathology of all cases was inversion papilloma, among which 3 cases had active cell growth and no carcinoma was seen. 23 cases had no tearing, no facial numbness, 2 cases had mild nasal subluxation, and 10 cases had nasal dryness. 3. Discussion With the wide application of endoscopic technology in rhinology, the indications for endoscopic surgery have also been expanding. Since the 1980s, endoscopic techniques for the surgical treatment of nasal invagination papilloma have achieved excellent results. The key to successful surgical treatment is to locate the base of the tumor and the extent of tumor invasion, and to completely remove the tumor. Preoperative assessment of the extent of the lesion is based on imaging, and CT is good at showing bony structures, but it is difficult to distinguish tumor tissue from surrounding inflammatory tissue and retained secretions, thus CT often leads to an overestimation of the extent of the tumor. In general, MRI shows moderate signal in the T2 phase, while inflammation around the tumor shows high signal. Therefore, CT combined with MR examination is valuable for the evaluation of tumor extent. Whether surgical resection can be complete is the key to effectively avoid recurrence. The scope of nasal endoscopic surgical resection and the choice of surgical procedure depend on the location of the tumor base, the extent and nature of the tumor (whether it is malignant or not). The surgical procedures can be divided into small-scale tumor resection, total pterygoidectomy, maxillary sinus (enlarged) endoscopic resection, Draf III frontal sinus surgery and combined nasal approach and endoscopic approach. In our group, we are Krouse II and III cases, all of which were completely resected by total septate sinus resection + maxillary sinus (enlarged) medial wall resection under nasal endoscopy, and no Krouse’s incision was performed to avoid facial scarring, etc. The tumor tissue was excised in pieces with a cutting suction device and trauma electrocoagulation to remove about 2 mm of soft tissue around its base. If conditions permit, the basal bone can be polished with a diamond drill. Intraoperatively, as much normal tissue at the tumor margin as possible is preserved and the sinuses are opened as widely as possible to facilitate postoperative follow-up. Intraoperative separation is performed with suction stripper or assistant-assisted suction, controlled hypotensive anesthesia, and electrocoagulation to reduce bleeding to obtain good visualization. When chiseling the bone, the assistant fixes the head position, and the harder maxillary frontal process and the bone at the edge of the pyriform foramen can be used with medullary forceps, gun type maxillary sinus biting forceps, and swallow tail chisel, and the direction of chiseling must be accurately controlled. Different angled endoscopes with angled scrapers can remove the diseased mucosa of the maxillary sinus in all directions. In conclusion, skillful endoscopic technique and the ability to accurately locate the lesion is also a guarantee of a smooth operation. We believe that for the frontal sinus, which may be large in extent due to the large variation in its degree of pneumatization, an extra-nasal approach or the Draf III procedure is required; for the extension of the pterygoid sinus toward the pterygoid process a partial excision of the upper part of the lateral wall of the posterior nostril is required. In this case, nasal endoscopic surgery is more difficult, so the patient should be prepared to change the procedure at the time of surgery. Postoperative patients should be followed up nasal endoscopically every 3-6 months and should be adhered to for life. We believe that early detection of recurrent lesions can be achieved by nasal endoscopy, and pathological diagnosis by biopsy is advisable to distinguish between granulation or edematous hyperplasia tissue, and then CT is performed to clarify whether there is skull base involvement. In our group, three cases recurred within one year, and the lesions were located in the hidden frontal fossa area, which was related to incomplete lesion excision. For the endoscopic view is more hidden or important parts (blood vessels, nerves, skull base) should be carefully resected. Foreign scholars reported that there is still a recurrence rate of 12%-17% after surgery, and it mostly occurs within one year after surgery [8, 9, 10], so it is necessary to insist on postoperative follow-up. Therefore, for Krouse stage II and III cases, nasal endoscopic maxillary sinus (enlarged) endosseous resection is basically close to the surgical scope of lateral nasal dissection, with no facial scarring, less trauma, clear surgical field, ability to accurately and completely remove the tumor, and low postoperative recurrence rate, which is worth promoting and applying. For the disadvantages such as hyperventilation, dryness, headache and crusting of the nasal cavity caused by excessive resection can be overcome by flushing or nebulization, and this point is not obvious in the young age. Nasal subluxation is associated with excessive resection of adjacent bone.