Inverted papilloma of the palate with malignant transformation.

The inverted papilloma is a unilateral sinonasal benign tumor which is characterized by aggressive local invasion, high recurrence rate, and transformation into malignancy. The etiology of inverted papilloma is still unknown. Possible causes include allergy, chronic sinusitis, occupational exposure to dusts and aerosols, tobacco, and viral infections. Treatment is complete surgical excision and close postoperative follow-up is necessary. Here we report a case of inverted papilloma arising from the hard palate with malignant transformation in a 41-year-old female. Clinical and histological features and treatment are discussed with the review of literature.

INTRODUCTION

Inverted papilloma is a true epithelial neoplasm characterized by hyperplastic epithelium inverting into the underlying connective tissue.[1] The first description of this entity was made by Ward in1854.[2] This lesion originates from the lateral nasal cavity wall or a paranasal sinus, usually the antrum and appears as a soft, pink or brown, polypoid or nodular growth.[3] The etiology of inverted papilloma is still unknown. Possible causes include allergy, chronic sinusitis, occupational exposure to dusts and aerosols, tobacco, and viral infections.[24] A strong male predilection is noted with greater prevalence in Caucasians.[35] The characteristic features of inverted papilloma are the presence of associated nasal polyps, its tendency to recur, destructive potential, and malignant transformation.[6] Recurrences after conservative surgical excision have occurred in 75% of cases and transformation to malignancy, usually SCC, in 3–24% of cases.[3] As a result, close postoperative follow-up is necessary for early detection of recurrences and malignant transformations.

CASE REPORT

A 41-year-old woman presented to the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran, with a chief complaint of a nodule on the hard palate. The patient had a history of diabetes mellitus and clinical intraoral examination revealed a nodule measuring 0.5 × 0.7 cm with soft consistency. On radiographic studies no changes were seen. Excisional biopsy was performed and histological findings showed multiple islands of epithelium extending into the underlying connective tissue, suggestive of inverted papilloma with mild dysplasia. Recurrence occurred 3 months later. The patient returned 5 months later with a rapidly growing lobulated mass on the hard palate and maxillary alveolar ridge [Figure 1].

Figure 1

A lobulated mass on the hard palate and maxillary alveolar ridge

Surface ulceration was evident in some parts. Computed tomography (CT) scan of this massive lesion did not show sinus involvement and bone lysis [Figure 2]. Incisional biopsy was performed and severe hemorrhage was encountered during surgical manipulation. Palatal biopsy showed epithelial proliferation with multiple inverting islands of epithelium extending into the underlying connective tissue. Invading lesion cells showed abundant eosinophilic cytoplasm with large hyperchromatic nuclei. Varying degrees of cellular and nuclear pleomorphism and individual cell keratinization were seen [Figure 3]. A diagnosis of inverted papilloma with malignant transformation to squamous cell carcinoma was established. The patient was sent for chemotherapy before surgery and the treatment has not come to an end yet.

Figure 2

CT scan did not show sinus involvement and bone lysis

Figure 3

Varying degrees of cellular and nuclear pleomorphism and individual cell keratinization were demonstrated

DISCUSSION

Inverted papilloma (Schneiderian papilloma) is considered the most common benign sinonasal tumor and it is characterized by aggressive local invasion, high recurrence rate, and transformation into malignancy.[7] The name “inverted” is justified by the endophilic growth pattern of the superficial epithelium. Inverted papilloma originates from the nasal cavity lateral wall, and it secondarily affects the maxillary, ethmoidal, frontal, and sphenoidal sinuses.[8] The incidence ranges from 0.5 to 4% of all primary nasal tumors and it is prevalent in the fifth and sixth decades of life.[7] It is three times more common in males than in females.[3] The symptoms include nasal obstruction, hyposmia, frontal headache, epistaxis, and rhinorrhea (Buchwald et al., 1989; 1995b).[89] Diagnosis is accomplished by history taking, otorhinolaryngological examination, and radiography.[10] CT scan is considered the investigation of choice (Lund and Lloyd, 1984) but the size of an Inverted Papilloma may be exaggerated by CT (Lund, 2000). With MRI the tendency to overestimate the size of IP is less than that with CT (Oikawa et al., 2003).[11]

Treatment is complete surgical excision, but in cases associated with SCC the lesion is treated as a malignancy by performing more radical surgery with or without radiotherapy and chemotherapy.[23] Recurrences are usually noted within 2 years of surgery and smoking is associated with increased risk of recurrence.[3] Its potential for malignant transformation is quite high.[1] Patients with carcinoma in IP are older than those IP patients without carcinoma and they are predominantly males.[12] Kumar et al. (2003) reported two cases of nasal inverted papillomas in 60- and 73-year-old males with malignant transformation.[1] Laton et al. (1986) reported one case of nasal inverted papilloma with focal malignant transformation.[13] In the case we presented inverted papilloma had originated from the hard palate without sinonasal involvment, which is quite different from what we know about the origin of inverted papilloma in the literature. In this case, the tumor was limited to the palate; therefore, complete resection was achieved by an intraoral surgery.