Schneiderian
papilloma (SP) are uncommon
tumors with malignant transformation even less common. The histologic criteria to define malignant transformation are not well developed nor is the immunohistochemical profile reported in a large series of
carcinomas. 20 cases of malignant transformation of SP included 7 females and 13 males, aged 38-86 years (mean 60.7 years). Patients presented most frequently with a mass (n = 11) and obstructive symptoms (n = 7), present for 38.7 months (mean). Most patients had no previous history of SP (n = 13); metachronous
carcinoma was identified in 7 patients an average of 34.4 months after the first diagnosis of SP, with 1-4 recurrences of SP. With a mean size of 4.1 cm, the majority of
tumors involved a combination of more than one anatomic site (n = 10), followed by the maxillary sinus only (n = 5) or nasal cavity only (n = 3). Histologically, 17 were inverted and 3 exophytic type SP. There were 17
squamous cell carcinomas, 2
mucoepidermoid carcinomas and 1
sinonasal undifferentiated carcinoma, comprising from 10 to 95 % of the
tumor volume. Malignant histologic features included atypical mitoses,
necrosis, bone invasion, lymphovascular invasion, decreased transmigrating neutrophils, paradoxical maturation, dyskeratosis and/or perineural invasion (n = 3). Patients tended to present with advanced stage (n = 14, Stage III and IV). Immunohistochemical studies showed positive reactions in the
malignancies for CK5/6 (86 %), p63 (86 %), CK7 (
luminal, 50 %), p53 (83 %), and p16 (25 %). In situ hybridization detected human papillomavirus in 26 %. Surgery was often accompanied by
radiation therapy (n = 13), with a mean of 2.4 years of follow-up. Five patients developed a recurrence between 0.8 and 3.3 years.
Carcinomas ex-SP are less common and are associated with better outcome than previously reported. Patients tend to present with a synchronous
carcinoma, developing in an inverted type SP, with
squamous cell carcinoma the most common
malignancy. Development of metachronous
carcinomas ex-SP was always preceded by SP recurrence in this series.