Expression of bone morphogenic protein in sinonasal inverted papilloma with new bone formation

Abstract

Inverted papilloma (IP) is a common benign tumor in the nose and sinus. Osteogenesis in sinonasal IP is extremely rare; to date, only five cases of IP with new bone formation appear in the literature. In addition, the mechanism of osteogenesis in IP remains unclear. Here, we describe three cases of IP with new bone formation and an investigation into a possible role for bone morphogenic protein (BMP) in osteogenesis. Of three patients with sinonasal IP with new bone formation, two were treated by endoscopic sinus surgery and one was followed up with watchful waiting. Tumor tissues were subjected to immunohistochemistry to detect BMP expression. The patients were successfully treated surgically and showed no evidence of recurrence postoperatively. Follow-up examination is ongoing. Immunohistochemically, the tumors expressed BMP-4 but not BMP-2 or BMP-7. ESS could be successfully used to achieve complete removal of the sinonasal IPs with new bone formation. BMP-4 might be associated with new bone formation in the tumor.

Keywords: Bone formation; bone morphogenic protein; endoscopic sinus surgery; inverted papilloma; sinonasal.

Figure 1.

Case 1 showing (a) axial and (b) horizontal enhanced computed tomography (CT) with an inhomogeneously enhancing mass, which filled the right nasal cavity, with marked osteogenesis.

Figure 2.

Case 1. Macroscopic ([a] the whole; [b] the cross-section) and (c) microscopic (100× magnification) features of the excised tumor. Histological examination showed a papillomatous proliferation of tumor cells with new bone formation consisting of randomly organized trabeculae lined by osteoblasts. Black arrows and asterisk denote bone tissue.

Figure 3.

Case 2. A series of axial computed tomography (CT) images over time showed a gradually enlarging tumor in the left nasal cavity. As the tumor enlarged, the bone enlarged. The patient was successfully treated by endoscopic sinus surgery. (a) March 2005, (b) November 2006, (c) July 2007, (d) May 2008, and (e) March 2010 (20 months postoperatively).

Figure 4.

Case 3. (a) Axial and (b) horizontal enhanced computed tomography (CT) showed an inhomogeneously enhancing mass, which filled the left nasal cavity, with marked osteogenesis.

Figure 5.

Immunohistochemistry for bone morphogenic protein (BMP; [a–c and g–l] 100× magnification; [d and f] 400× magnification). (a, d, g, and j) BMP-2, (b, e, h, and k) BMP-4, and (c, f, i, and l) BMP-7. IPB cells were strongly positively stained for BMP-4 and produced a negative result after staining for BMP-2 and BMP-7. IPB, inverted papilloma with new bone formation; IPC, inverted papilloma without bone formation (common type); NP, nasal polyp. *Bone tissue.