Low-grade Papillary Schneiderian Carcinoma, a Unique and Deceptively Bland Malignant Neoplasm

Abstract

The sinonasal tract harbors several different types of papillomas, some of which can progress to carcinoma. The most frequent among these are inverted and oncocytic Schneiderian papillomas. The rates of progression are somewhat controversial but are approximately 5% to 10% and are almost invariably described in the literature as in situ or invasive squamous cell carcinoma. Other carcinoma types, such as mucoepidermoid and sinonasal undifferentiated carcinoma, have also been described. Almost all of the described patterns of malignancy involve frank carcinoma with overtly dysplastic nuclear features, lack of cell maturation, and increased mitotic activity. Some squamous cell carcinomas, particularly nonkeratinizing, can grow in a papillary pattern, appearing to only line the surface epithelium, but they are cytologically overtly malignant throughout. In this case report, however, we describe a novel, human papillomavirus-negative, papillary carcinoma, which presented as a left nasal and maxillary sinus exophytic and inverted-appearing, papillomatous mass with very bland cytomorphology. The initial features were not typical for any defined Schneiderian papilloma but were also not clearly diagnostic of papillary carcinoma. The tumor recurred >10 times over 18 years despite extensive surgical resection including orbital exenteration. The tumor retained a bland appearance throughout the patient's entire clinical course, but did develop a pushing pattern of stromal invasion, increased mitotic activity, vesicular nuclei with prominent nucleoli, lymph node metastases, and eventually overwhelming local recurrence and nodal metastases, resulting in death. This tumor seems best characterized as a low-grade papillary Schneiderian carcinoma and appears to represent a novel type of sinonasal carcinoma.

Low-Grade Papillary Schneiderian Carcinoma: A Case Report

“…The present case also showed invasive, but bland histomorphology, and could not be classified according to the 2017 WHO classification of tumors of the nasal cavity and paranasal sinuses including squamous cell carcinoma, lymphoepithelial carcinoma, sinonasal undifferentiated carcinoma, NUT carcinoma, neuroendocrine carcinoma, adenocarcinoma, and teratocarcinosarcoma as malignant epithelial tumors. This case was similar to the novel entity reported by Lewis et al [ 4 ], although the clinical outcome is yet to be determined. Diffuse immunopositivity for p63, significant expression of p53, and partial positivity for p16 were also shared by the two cases.…”

“…Lewis et al [ 4 ] recently described a previously undocumented pathologic case in which a 47-year-old patient who was initially diagnosed with “fungiform Schneiderian papilloma”, and died after 18 years of progressive recurrence. Over time, the mitosis level increased from <1/10 HPFs to 18/10 HPFs, and the Ki-67 labeling index increased from 5 to 50–60% in the lymph node metastasis from late in the disease course.…”

“…The 2017 World Health Organization (WHO) histological classification of tumors of the nasal cavity and paranasal sinuses includes squamous cell carcinomas, lymphoepithelial carcinomas, sinonasal undifferentiated carcinomas, NUT carcinoma, neuroendocrine carcinoma, adenocarcinomas, and teratocarcinosarcoma with overtly malignant characteristics [ 3 ]. The low-grade papillary Schneiderian carcinoma, as recently described by Lewis et al [ 4 ], is a novel type of carcinoma characterized by bland morphology similar to that of the Schneiderian papilloma, an invasive growth pattern, and a propensity for multiple recurrences and ultimate mortality. Here, we report an additional case of low-grade papillary Schneiderian carcinoma.…”

Low-Grade Epithelial Proliferations of the Sinonasal Tract

“…The case report images show a combined exophytic and endophytic mass, somewhat resembling a low-grade papillary urothelial carcinoma. They have labelled this entity ''Low-grade Papillary Schneiderian Carcinoma'' [14]. So far, this appears to be a unique case.…”

Oncocytic Schneiderian papilloma-associated adenocarcinoma and KRAS mutation

“…Also, there are few reports on the biological behavior of OSP-related tumors after malignant transformation, such as in recurrence, lymph node metastasis, and distant metastasis. [ 14 ] Only 1 case described cervical lymph node metastasis after carcinoma arising in IP. [ 14 ] To our knowledge, metastasis following malignant transformation arising in OSP and the progress of the disease have not yet been reported.…”