Introduction
Inverted papillomata (IP) are rare and benign sinonasal tumours that account for 0.4-7% of sinonasal tumours excised, with an estimated annual incidence of 0.2-1.5 cases per 100,000. In patients, the highest incidence is seen in the 5th and 6thdecades of life, with a 2-5:1 male-to-female ratio (1,2). Despite being benign tumours, IPs are locally aggressive and have high recurrence rates of up to 78% (1). There is also a known association with malignancy, with a synchronous and metachronous carcinomatous rate estimated at 7.1% and 3.6% respectively (2). The aetiology of IP remains unknown, but evidence demonstrates an association with Human Papilloma Virus (HPV), p53 and p21 oncogenes in malignant transformation of IP (1).
Patients with IP can present with a variety of symptoms, including unilateral nasal obstruction, rhinorrhoea, epistaxis, facial pain, or hyposmia/anosmia (1,2). Conversely, IP can also present asymptomatically in 4-23% of cases with the IPs being an incidental finding (1).
On endoscopy, IPs appear as a reddish-grey, friable lobulated mass that is firmer than an inflammatory polyp. IPs are predominantly unilateral, with bilateral lesions accounting for 1-9% of cases (2). Histopathological diagnosis is essential for diagnosis and to rule out associated malignancy. Characteristic features on microscopy include the invagination of the superficial IP epithelium into the underlying stroma, hence the ‘inverted’ descriptor. The epithelium may be of the stratified squamous, ciliated pseudostratified columnar epithelium or transitional types (1,3).
Radiological assessment is essential to determine the tumour location and extension for surgical planning. Computed Tomography (CT) of the sinuses is widely used to evaluate sinonasal masses and assess for underlying bony changes. Unlike malignant tumours that cause bony destruction, IP causes hyperostosis or sclerosis. (1,2) Magnetic resonance imaging (MRI) can be useful in addition to CT scans to determine the lesion’s exact location and decide upon the best surgical approach. (2)
The optimal management of IP involves the complete surgical excision of the diseased mucosa and mucoperiosteum. (2) Historically, gold-standard management techniques involved external approaches such as a lateral rhinotomy with medial maxillectomy. (1) With the progression of minimally invasive techniques and high-quality imaging, endoscopic management techniques have become the gold standard for IP resection. Compared to external approaches, they result in lower recurrence rates and reduce surgical morbidity. (1,4) Due to the high recurrence rates associated with IP, a minimum follow-up period of five years is recommended (4).
As many cases managed in our centre had already undergone a previous procedure, the objective of this retrospective case series was to evaluate the outcomes for primary and secondary cases of sinonasal IP including recurrence rates and complication rates.