OBJECTIVE: We report a rare case of new bone formation (osteogenesis) within an inverted papilloma, occurring in the ethmoid and frontal sinuses. METHOD: The histopathological and radiological findings, differential diagnosis, and treatment of tumour-induced osteogenesis are discussed. RESULTS: A 68-year-old man complained of headache and left-sided, purulent rhinorrhoea of five years' duration. On nasal endoscopy, lesions similar to inflammatory nasal polyps were seen. Pre-operative radiological images demonstrated opacification of the left nasal cavity and anterior ethmoid and frontal sinuses, plus a bone-density lesion. The mass with bony lesion was completely removed endoscopically. The mass was histopathologically diagnosed as an inverted papilloma surrounding bony tissue. Furthermore, the histopathological findings (including immature bony tissue rimmed by osteoblasts) indicated an extremely rare case of inverted papilloma induced osteogenesis. Six months after surgery, no recurrence was detected. CONCLUSION: This case highlights the importance of clinical awareness of tumour-induced osteogenesis.
OBJECTIVE: We report a rare case of new bone formation (osteogenesis) within an inverted papilloma, occurring in the ethmoid and frontal sinuses. METHOD: The histopathological and radiological findings, differential diagnosis, and treatment of tumour-induced osteogenesis are discussed. RESULTS: A 68-year-old man complained of headache and left-sided, purulent rhinorrhoea of five years' duration. On nasal endoscopy, lesions similar to inflammatory nasal polyps were seen. Pre-operative radiological images demonstrated opacification of the left nasal cavity and anterior ethmoid and frontal sinuses, plus a bone-density lesion. The mass with bony lesion was completely removed endoscopically. The mass was histopathologically diagnosed as an inverted papilloma surrounding bony tissue. Furthermore, the histopathological findings (including immature bony tissue rimmed by osteoblasts) indicated an extremely rare case of inverted papilloma induced osteogenesis. Six months after surgery, no recurrence was detected. CONCLUSION: This case highlights the importance of clinical awareness of tumour-induced osteogenesis.