Loss of BAP1 expression is very rare in peritoneal and gynecologic serous adenocarcinomas and can be useful in the differential diagnosis with abdominal mesothelioma.

Gynecologic and primary peritoneal serous carcinoma may be difficult to distinguish from abdominal mesotheliomas clinically, morphologically, and immunohistochemically. BAP1 double-hit inactivation and subsequent loss of protein expression have been reported in more than half of all abdominal mesotheliomas. We therefore sought to investigate the expression of BAP1 in serous carcinoma and explore its potential utility as a marker in the differential diagnosis with mesothelioma. We searched the computerized database of the Department of Anatomical Pathology, Royal North Shore Hospital, Australia, for all cases of gynecologic and peritoneal serous carcinomas and mesotheliomas diagnosed between 1998 and 2014. Immunohistochemistry for BAP1 was then performed on tissue microarray sections. Cases with completely absent nuclear staining in the presence of a positive internal control in nonneoplastic cells were considered negative. If staining was equivocal (eg, absent nuclear staining but no internal control), staining was repeated on whole sections. Loss of BAP1 expression was found in only 1 of 395 (0.3%) serous carcinomas but in 6 of 9 (67%) abdominal mesotheliomas (P < .001) and 131 of 277 (47%) thoracic mesotheliomas (P < .001). We conclude that BAP1 loss occurs extremely infrequently in gynecologic and peritoneal serous adenocarcinomas, whereas it is very common in mesotheliomas including abdominal mesothelioma. Therefore, although positive staining for BAP1 cannot be used to exclude a diagnosis of mesothelioma, loss of BAP1 expression can be used to very strongly support a pathological diagnosis of abdominal mesothelioma over serous carcinoma.

Immunoregulatory Forkhead Box Protein p3-Positive Lymphocytes Are Associated with Overall Survival in Patients with Pancreatic Neuroendocrine Tumors.

BACKGROUND: Forkhead box protein p3-positive (FoxP3(+)) regulatory T cells (Tregs) suppress host T-cell-mediated immune responses, limit surveillance against cancers, and have been associated with a poor prognosis. STUDY DESIGN: This study aims to identify the prognostic significance of FoxP3(+) Tregs in pancreatic neuroendocrine tumors (PNETs). Patients diagnosed with PNETs between 1992 and 2014 (n = 101) were included in this retrospective analysis. Clinical data, histopathology, and expression of FoxP3(+) Tregs and Ki-67 by immunohistochemistry were assessed. The association of these factors with survival was tested by log-rank test and in additional multivariable analysis. RESULTS: A total of 101 patients were included in this study. Mean age was 58.0 years (range 18 to 87 years) and median tumor size was 25 mm (range 8 to 160 mm). The degree of infiltration of tumor by FoxP3(+) Tregs was graded as 0 (n = 75), 1 (n = 15), or 2 (n = 11). Median follow-up was 50 months (interquartile range 123 months; Q1 = 20 months and Q3 = 123 months). In univariate analyses, patient age older than 57 years, TNM stage III or IV, tumor size >25 mm, Ki-67 labeling index >20, and a high number of FoxP3(+) tumor-infiltrating lymphocytes were significantly associated with poorer overall survival. In multivariable analyses, FoxP3(+) expression score of 2 (hazard ratio = 6.9; 95% CI 1.4-34.4) was the only statistically significant predictor for overall mortality. CONCLUSIONS: FoxP3(+) Treg expression is an independent prognostic factor in patients with PNETs, associated with statistically significant shorter overall survival. There is a role for additional research into the immune-mediated role of FoxP3(+) Tregs in PNETs.

Somatostatin Receptor SSTR-2a Expression Is a Stronger Predictor for Survival Than Ki-67 in Pancreatic Neuroendocrine Tumors.

Somatostatin receptors (SSTR) are commonly expressed by neuroendocrine tumors. Expression of SSTR-2a and SSTR-5 may impact symptomatic management; however, the impact on survival is unclear. The aim of this study is to correlate SSTR-2a and SSTR-5 expression in pancreatic neuroendocrine tumors (PNETs) with survival. This study is designed to determine the prognostic significance of somatostatin receptors SSTR-2a and SSTR-5 in PNETs. This retrospective cohort study included cases of resected PNETs between 1992 and 2014. Clinical data, histopathology, expression of SSTR and Ki-67 by immunohistochemistry, and long-term survival were analyzed. A total of 99 cases were included in this study. The mean age was 57.8 years (18-87 years) and median tumor size was 25 mm (range 8-160 mm). SSTR-2a and SSTR-5 expression was scored as negative (n = 19, 19.2%; n = 75, 75.8%, respectively) and positive (n = 80, 80.1%; n = 24, 24.2%). The median follow-up was 49 months. SSTR-2a expression was associated with improved overall survival, with cumulative survival rates at 1, 3, and 5 years being 97.5%, 91.5%, and 82.9%, respectively. Univariate analysis demonstrated better survival in SSTR-2a positive patients (log rank P = 0.04). SSTR-5 expression was not associated with survival outcomes (log rank P = 0.94). Multivariate analysis showed that positive SSTR-2a expression is a stronger prognostic indicator for overall survival [Hazard Ratio (HR): 0.2, 95% Confidence interval (CI): 0.1-0.8] compared to high Ki-67 (HR: 0.8, 95% CI: 0.1-5.7). Expression of SSTR-2a is an independent positive prognostic factor for survival in PNETs.