Newly Described Tumor Entities in Sinonasal Tract Pathology

Abstract

Surgical pathology of the sinonasal tract (nasal cavity and paranasal sinuses) is extremely challenging due in part to the tremendous diversity of tumor types that may arise in this region. Compounding the difficulty, a number of new sinonasal tumor entities have been recently described, and pathologists may not yet be familiar with these neoplasms. This manuscript will review the clinicopathologic features of some of the newly described sinonasal tumor types: NUT midline carcinoma, HPV-related carcinoma with adenoid cystic-like features, SMARCB1 (INI-1) deficient sinonasal carcinoma, biphenotypic sinonasal sarcoma, and renal cell-like adenocarcinoma.

Keywords: Biphenotypic sinonasal sarcoma; HPV-related carcinoma with adenoid cystic-like features; NUT midline carcinoma; Renal cell-like adenocarcinoma; SMARCB1 (INI-1) deficient sinonasal carcinoma.

Fig. 1

NUT midline carcinoma grows as nests of tumor cells in the sinonasal submucosa (a). NUT midline carcinoma often exhibits a peculiar form of “abrupt” keratinization (b). NUT midline carcinomas have high mitotic rates, but they are very monotonous at the cellular level, with minimal nuclear pleomorphism (c). The diagnosis is confirmed by NUT-1 immunochemistry, which is diffusely positive in a nuclear distribution in NUT midline carcinoma. The immunostaining usually has a speckled quality (d)

Fig. 2

HPV-related carcinoma with adenoid cystic-like features grows as basaloid nests, trabeculae, and cribriform structures. The surface exhibits squamous dysplasia. a Like adenoid cystic carcinoma, HPV-related carcinoma with adenoid cystic-like features is biphasic with myoepithelial cells that are positive for p63 (b) and ducts that are positive for c-kit (c). Both the invasive tumor and the dysplastic surface are positive for p16 by immunohistochemistry (d) and HPV by in situ hybridization (inset)

Fig. 3

SMARCB1 (INI-1) deficient sinonasal carcinoma invades as basaloid nests beneath a normal surface epithelium. Tumor necrosis is evident (a). SMARCB1 (INI-1) deficient sinonasal carcinoma is typically highly infiltrative, with frequent invasion of bone (b). Variable numbers of rhabdoid tumor cells are frequently found in SMARCB1 (INI-1) deficient sinonasal carcinoma (c). By definition, this entity is completely negative for SMARCB1 (INI-1) by immunohistochemistry (d)

Fig. 4

Biphenotypic sinonasal sarcoma is a highly cellular spindle cell proliferation. Frequently, non-neoplastic surface glands become entrapped within the tumor (a). The tumor cells of biphenotypic sinonasal sarcoma are arranged in fascicles, sometimes in an alternating “herringbone” pattern (b). Biphenotypic sinonasal sarcoma is almost always focally positive for both actin (c) and S100 protein (d)

Fig. 5

Sinonasal renal cell-like adenocarcinoma grows as nests and follicles (a) of cells with abundant, optically clear cytoplasm (b). Unlike true renal cell carcinoma, however, sinonasal renal cell-like adenocarcinoma is often positive for S100 (c) and is always negative for the renal-specific marker PAX-8 (d)