Expression of calretinin in high-grade hormone receptor-negative invasive breast carcinomas: correlation with histological and molecular subtypes

The Diagnostic Utility of IDH2 R172 Immunohistochemistry in Tall Cell Carcinoma With Reversed Polarity of the Breast

Tall cell carcinoma with reversed polarity (TCCRP) is a rare histologic type of low-grade breast cancer, consisting of tall columnar cells with reversed nuclear polarity and characterized by frequent IDH2 mutations. We herein report 3 cases of TCCRP with sequencing analyses of the IDH2 gene and immunohistochemical examination using monoclonal antibodies (11C8B1) against IDH2 R172. IDH2 R172 mutations were detected in all 3 resected tumors (R172S in 2 tumors and R172T in 1 tumor), and the presence of these mutations was confirmed by IDH2 R172 immunohistochemistry. Tumor cells of TCCRP showed strong and diffuse staining for the antibody against IDH2 R172. In 1 case, tumor tissue from 2 core needle biopsy samples collected on different days were also immunohistochemically positive for IDH2 R172. These results indicate that IDH2 R172 immunohistochemistry is suitable for the detection of TCCRP in both resection and biopsy samples. In addition, a literature review revealed that R172S and R172T account for 76% of IDH2 mutations in TCCRP, suggesting that 11C8B1, which reacts with R172S and R172T, was likely most sensitive for IDH2-mutated TCCRP among many available antibodies for IDH2 R172. Furthermore, the combination of 2 or more antibodies against IDH2 R172 could be more effective for detecting TCCRP mutation. However, it is important to note that IDH2 R172 immunohistochemistry is not absolute, because IDH2 wild type is found in a small proportion (10%) of cases, and a few cases of IDH2-mutated TCCRP may harbor rare subtypes of R172 that are not covered by available antibodies.

State-of-the-art cytology of pleural fluid, focusing on the diagnosis of mesothelioma

Mesothelioma has always been a challenging diagnosis to render in body cavity cytology samples. This review is a timely update on pleural fluid cytology and ancillary studies that should be considered in the diagnosis of mesothelial proliferations, specifically mesotheliomas. Information about new diagnostic approaches and ancillary studies in mesothelioma was obtained from the peer-reviewed literature and the authors' experiences. Although the morphological diagnosis of mesothelioma is fraught with numerous challenges given the overlap with other diagnostic entities, there are a variety of immunohistochemical and fluorescence in situ hybridization studies available to help in determining mesothelial origin and in distinguishing malignant proliferations from the more common benign or reactive mesothelial proliferations. Although ancillary studies can be helpful, there are important pitfalls to be aware of when interpreting these cases, and this review highlights some of the challenges that require caution.

Serum calretinin as an independent predictor for platinum resistance and prognosis in ovarian cancer

Calretinin (CRT) is a calcium-binding protein that controls intracellular calcium signaling. Besides its prominent expression in neurons, serum CRT (sCRT) has recently been suggested as blood-based biomarker for prediagnostic mesothelioma detection. CRT is expressed in ovarian cancer tissues in up to 40% of cases; however, its clinical relevance as blood-based biomarker for ovarian cancer is unknown. sCRT was determined by calretinin enzyme-linked immunoabsorbent assay (Calretinin-ELISA, DLD Diagnostika GmbH, Hamburg, Germany) in a total of 515 serum samples from 116 healthy controls and 134 ovarian cancer patients (thereof 86% with Fédération Internationale de Gynécologie et d'Obstétrique [FIGO] III/IV), including samples at primary diagnosis and at four longitudinal follow-up time points in the course of treatment and at recurrence. sCRT level was significantly increased in ovarian cancer patients compared to healthy controls (estimated difference = 0.3 ng/ml, p < 0.001), was mostly independent from CA125 (r ≤ 0.388) and enabled accurate discrimination between cases and controls (area under the curve = 0.85). Higher sCRT level at primary diagnosis predicted suboptimal debulking (p < 0.001) and was associated with advanced FIGO-stage (p < 0.001) and increased amount of ascites (p < 0.001). sCRT levels at primary diagnosis and its dynamics in the course of chemotherapy were independent predictors for poor progression-free survival (hazard ratio [HR] = 1.99, confidence interval [CI] = [1.13-3.52], p = 0.0181) and overall survival (HR = 15.4, CI = [1.92-124], p = 0.0099). Furthermore, sCRT at primary diagnosis or a relative sCRT increase in the time interval between surgery and the onset of chemotherapy were both independent predictors of platinum resistance (OR = 4.99, CI = [3.50-16,001], p = 0.0016; OR = 2.41, CI = [1.37-6,026], p = 0.0271, respectively). This is the first study that suggests sCRT as liquid biopsy marker for independent prediction of platinum resistance and prognosis.

Solid papillary carcinoma with reverse polarity of the breast harbors specific morphologic, immunohistochemical and molecular profile in comparison with other benign or malignant papillary lesions of the breast: a comparative study of 9 additional cases

Solid papillary carcinoma with reverse polarity is a rare breast cancer of favorable prognosis that can be difficult to diagnose. We report here nine additional cases of this tumor, and we describe its morphologic, immunohistochemical and molecular profile in comparison to other types of papillary and micropapillary lesions of the breast that are intraductal papilloma with usual ductal hyperplasia, encapsulated papillary carcinoma, solid papillary carcinoma and invasive micropapillary carcinoma. We studied nine cases of this special papillary tumor and six of each other types mentioned above. We found that solid papillary carcinoma with reverse polarity harbor specific morphologic features as cuboid or tall cells with abundant eosinophilic cytoplasms located at the basal pole giving the impression of reverse nuclear polarity. Nuclei were sometimes grooved. Immunohistochemistry demonstrated the lack of myoepithelial cells, as in encapsulated papillary carcinoma and solid papillary carcinoma, questioning their invasive nature. Seven of nine solid papillary carcinoma with reverse polarity showed a low Ki67 proliferative index (Ki67 <5%). They showed expression of CK5/6 as in intraductal papilloma with usual ductal hyperplasia. They showed expression of calretinin and a low or lack of hormonal receptor (HR) expression that were not observed in other breast tumors studied. By whole-exome analysis, seven of nine solid papillary carcinomas with reverse polarity (78%) harbored a hotspot mutation in IDH2 (R172) that was totally absent in other groups. Six of nine tumors (67%) also harbored PRUNE2 mutation, including the two IDH2 wild-type cases. We also demonstrated for the first time in this breast tumor, immunostaining with a specific antibody IDH1/2 mutant R132/R172 (7/9) that can highlight IDH2 mutation. Moreover, transcriptomic analysis showed that proteoglycan pathway was significantly enriched. Our findings support the fact that solid papillary carcinoma with reverse polarity is a singular breast neoplasm that can be distinguished from other papillary breast tumors.