PTEN inactivating mutations are associated with hormone receptor loss during breast cancer recurrence.

Purpose: Hormone receptor (HR) status may be unstable during breast cancer (BC) progression, and changes occur in approximately 20-30% of BC patients at the time of recurrence. The biologic tumor switch from HR+ to HR- status is associated with worse clinical outcomes and warrants alternative management. We aimed to characterize clinical and pathologic features of a subset of ER+/HER2- breast cancer patients who converted to triple negative phenotype upon recurrence, and investigate the molecular alterations associated with HR loss during BC progression.

SMARCB1 (INI1)-deficient sinonasal carcinoma: a series of 13 cases with assessment of histologic patterns.

A significant proportion of sinonasal malignancies comprise poorly differentiated/undifferentiated carcinomas that defy accurate histologic classification and behave aggressively. Recent years have seen a refinement of this spectrum by inclusion of novel entities harboring specific genetic alterations, including SMARCB1 (INI1)-deficient sinonasal carcinoma (SDSC), characterized by inactivating alterations in SMARCB1 gene, as demonstrated by loss of INI1 immunoexpression. Cyclin D1 is a cell-cycle regulatory protein downstream of INI1.

NUT Midline Carcinoma: A Series of Five Cases, Including One with Unusual Clinical Course.

NUT midline carcinomas (NMCs) are rare, poorly differentiated tumors with aggressive biological behavior and a characteristic molecular signature. Availability of NUT antibody has facilitated diagnosis of NMC without molecular testing. We report a series of head and neck NMCs diagnosed using NUT IHC at our institute, including one case with an unusual course.