Kamaljeet Singh

Claudin Expression in High Grade Invasive Ductal Carcinoma of the Breast: Correlation with the Molecular Subtype

Claudin proteins are a major component of the tight junctions. Dysregulation of claudin protein expression has been described in a number of malignancies. Gene expression profiling has stratified breast cancers into distinct molecular subtypes: luminal, HER2 positive (HER2+), and basal-like. Recently, a novel claudin-low molecular subtype has been described. In this study, we correlated the expression patterns of claudins with the molecular subtypes of breast cancer. On the basis of immunohistochemical expression, 226 grade 3 invasive ductal carcinomas were stratified into 65 luminal (estrogen receptor positive (ER+)), 65 HER2+, 86 basal-like, including 14 metaplastic carcinomas (ER−, HER2−, CK5/6, and/or epidermal growth factor receptor positive), and 10 unclassified. Tissue microarrays were analyzed for the expression of claudins 1, 3, 4, 7, and 8 by immunohistochemistry and scored semiquantitatively. High levels of expression were detected in 17% of all cases for claudin 1, 32% claudin 3, 41% claudin 4, 44% claudin 7, and 40% claudin 8. Luminal cancers exhibited increased claudins 7 and 8; basal-like tumors demonstrated increased expression of claudins 1 and 4. Low expression of all five claudins was detected in 30 of 226 cases (13%) and this group was designated ‘claudin-low’. The majority of the claudin-low subgroup were basal-like cancers (23 of 30, 77%). In contrast, only 1 of 30 (3%) claudin-low tumors was of the luminal phenotype and 6 of 30 cases (20%) were HER2+ (P<0.001). Within the basal-like subgroup, 64% of the metaplastic and 19% of the non-metaplastic tumors were claudin-low. The claudin-low group was strongly associated with disease recurrence (P=0.0093). In conclusion, this study is the first to examine comprehensively the differential expression of claudins 1, 3, 4, 7, and 8 in the molecular subtypes of high-grade breast cancer. Claudin-low subtype is a frequent phenomenon in metaplastic and basal-like breast cancer and appears to be a strong predictor of disease recurrence.

Orbital Necrobiotic Xanthogranuloma Associated With Systemic IgG4 Disease

Purpose: The authors describe 2 cases of orbital xanthogranulomatous disease associated with an increase in IgG4-positive plasma cells, and also examine IgG4 in other types of orbital inflammation. Methods: Immunohistochemistry for total IgG and IgG4 was performed in 18 cases of orbital inflammation, including chronic dacryoadenitis (n = 10), necrobiotic xanthogranuloma (n = 2), xanthogranuloma (n = 1), idiopathic orbital inflammation/pseudotumor (n = 4), and fungal infection (n = 1). Results: One patient presenting with necrobiotic xanthogranuloma had signs of systemic IgG4 disease. His orbital lesion showed an elevated number of IgG4 positive plasma cells (55%). An orbital xanthogranulomatous lesion in a second patient lacking systemic symptoms also contained a high percentage of IgG4-positive plasma cells (80%). Only 1 case of chronic dacryoadenitis contained prominent IgG4-positive plasma cells (mean 17/hpf). Conclusions: IgG4-positive plasma cells are relatively rare in nonsclerosing orbital inflammatory lesions. However, systemic disease IgG4 can be associated with necrobiotic xanthogranuloma of the orbit.

Promotion of cytoplasmic mislocalization of p27 by Helicobacter pylori in gastric cancer

The cyclin-dependent kinase (CDK) inhibitor p27 has an important role in cell cycle regulation. Reduced expression of p27 is commonly associated with poor prognosis in many malignancies, including gastric cancer. Cytoplasmic p27 mislocalization may be an additional indicator of high-grade tumors and poor prognosis in cancer. As chronic infection by Helicobacter pylori is the most important risk factor for gastric cancer development, we evaluated the effects of H. pylori on p27 expression and localization in gastric cancer cells. Co-culture of gastric cells with H. pylori induced cytoplasmic p27 expression and reduced nuclear p27 expression in vitro. Cytoplasmic p27 expression was associated with and dependent upon phosphorylation of p27 at T157 and T198: wild-type p27 accumulated in the cytoplasm, but non-phosphorylatable mutants affecting T157 or T198 were nuclear in H. pylori-infected cells. These post-translational p27 changes were secondary to activation of cellular phosphoinositide-3 kinase (PI3K) and AKT signaling pathways, and dependent upon a functional H. pylori cag pathogenicity island. We investigated the clinical significance of cytoplasmic p27 mislocalization in 164 cases of resected gastric cancer in tissue microarrays. In 97 cases (59%), cytoplasmic p27 mislocalization was observed, and this was associated with increased mortality in multivariate analysis. These results show that H. pylori infection induces AKT/PI3K-mediated phosphorylation of p27 at T157 and T198 to cause cytoplasmic p27 mislocalization in gastric cancer, and that p27 mislocalization is an adverse prognostic feature in gastric cancer. This is the first demonstration of the translocation of a specific bacterial virulence factor that post-translationally regulates a host cell CDK inhibitor. This is of particular significance, because p27 has both tumor-suppressive and oncogenic activities, depending upon its subcellular localization. Cytoplasmic mislocalization of p27 induced by H. pylori may be an important mechanistic link between H. pylori infection and gastric carcinogenesis.

The molecular basis of breast cancer pathological phenotypes.

The histopathological evaluation of morphological features in breast tumours provides prognostic information to guide therapy. Adjunct molecular analyses provide further diagnostic, prognostic and predictive information. However, there is limited knowledge of the molecular basis of morphological phenotypes in invasive breast cancer. This study integrated genomic, transcriptomic and protein data to provide a comprehensive molecular profiling of morphological features in breast cancer. Fifteen pathologists assessed 850 invasive breast cancer cases from The Cancer Genome Atlas (TCGA). Morphological features were significantly associated with genomic alteration, DNA methylation subtype, PAM50 and microRNA subtypes, proliferation scores, gene expression and/or reverse‐phase protein assay subtype. Marked nuclear pleomorphism, necrosis, inflammation and a high mitotic count were associated with the basal‐like subtype, and had a similar molecular basis. Omics‐based signatures were constructed to predict morphological features. The association of morphology transcriptome signatures with overall survival in oestrogen receptor (ER)‐positive and ER‐negative breast cancer was first assessed by use of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset; signatures that remained prognostic in the METABRIC multivariate analysis were further evaluated in five additional datasets. The transcriptomic signature of poorly differentiated epithelial tubules was prognostic in ER‐positive breast cancer. No signature was prognostic in ER‐negative breast cancer. This study provided new insights into the molecular basis of breast cancer morphological phenotypes. The integration of morphological with molecular data has the potential to refine breast cancer classification, predict response to therapy, enhance our understanding of breast cancer biology, and improve clinical management. This work is publicly accessible at www.dx.ai/tcga_breast. Copyright

Calretinin expression in high-grade invasive ductal carcinoma of the breast is associated with basal-like subtype and unfavorable prognosis.

Calretinin, a calcium-binding protein, is a widely used marker for mesothelial differentiation. There is accumulating evidence of calretinin expression in epithelial and mesenchymal malignancies, as well. The objectives of this study were to (1) further delineate the expression of calretinin in grade 3 breast carcinomas in the context of molecular subtypes and (2) identify the impact of calretinin expression on overall and disease-free survival. On the basis of immunohistochemical expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor-2 (HER2), cytokeratin 5/6, and epidermal growth factor receptor, 214 grade 3 invasive ductal carcinomas were stratified into 36 luminal A, 63 luminal B, 24 HER2 positive, 81 basal-like (including 13 metaplastic carcinomas), and 10 unclassified. Tissue microarrays were analyzed for immunohistochemical expression of calretinin. High-level calretinin expression was identified in a significant proportion of basal-like (54.3%), HER2 (33.3%), and unclassified (30%) tumors. In contrast, luminal A and B subtypes demonstrated high-level calretinin expression in only 11.1% and 12.7%, respectively (P < .0001). Within the basal-like group, 38.5% of the metaplastic carcinomas demonstrated high-level expression, associated predominantly with the epithelial component and squamous metaplasia. High-level calretinin expression was strongly associated with decreased overall survival in the entire cohort of grade 3 cancer (P = .0096) and in the basal-like group (P = .039). Multivariate analysis revealed that both tumor stage and high-level calretinin expression were independent predictors of overall survival (P = .0002 and P = .0023, respectively). In conclusion, high-level calretinin expression is most common in grade 3 tumors with a basal-like phenotype and is associated with poor overall survival.

‘Inside‐out’ p120 immunostaining pattern in invasive micropapillary carcinoma of the breast; additional unequivocal evidence of reversed polarity

Invasive micropapillary carcinoma (IMPC) of the breast is a distinct histologic variant of ductal carcinoma in which tumor cells display reverse polarity. Tumor cells form morula-like clusters and tubular structures suspended in a clear space, with a characteristic “inside-out” pattern.1 Although IMPC can be readily identified by its typical histological features, immunohistochemistry (IHC) for epithelial membrane antigen (EMA) and sialyl Lewis X can be employed to confirm this “inside-out” pattern, especially where the IMPC component is focal.2 By IHC, EMA highlights the apical pole of the tumor cell membrane, which faces the empty space and the stroma, confirming the reverse polarization. Immunohistochemistry for E-cadherin, a component of adherens-type junction, also demonstrates “inside-out” pattern in IMPC: Positivity in lateral cell borders with sparing of the apical portion of the cell, also referred to as a “cup-shaped” staining pattern.3 Since p120 catenin is bound to the juxtamembrane intracytoplasmic domain of e-cadherin, we proposed that in IMPC, as with E-cadherin, p120 catenin expression should be limited to lateral cell borders with no apical positivity. This article is protected by copyright. All rights reserved.

Expression of p16 and p53 in Intraepithelial Periocular Sebaceous Carcinoma

Purpose: Identifying intraepithelial sebaceous carcinoma cells in small periocular biopsies can be difficult, particularly in the conjunctiva. The goal of this study was to evaluate p53 and p16 immunohistochemistry as potential markers of intraepithelial sebaceous carcinoma. Procedures: A total of 25 tumors, including 4 recurrent lesions, were stained for p16 and p53, with intensity scored as negative, weak, moderate or strong. Results: Expression of p16 was detected in intraepithelial sebaceous carcinoma cells in 24 of the 25 cases (96%), with only 1 case showing weak immunoreactivity. Intraepithelial p53 immunoreactivity was present in 17 of 25 tumors (68%), but was weak in 3 cases. Expression levels remained relatively stable in primary and recurrent tumors, but varied in a few cases between intraepithelial and subepithelial sites. Conclusions: Intraepithelial sebaceous carcinomas stained for p53 and p16 demonstrated moderate to strong immunoreactivity in 100% of cases for at least one of these proteins, suggesting that together they are useful markers for determining the extent of tumor spread. Of the two, p16 was immunoreactive in more cases than p53.

ColXα1 is a Stromal Component that Colocalizes with Elastin in the Breast Tumor Extracellular Matrix: ColXα1 and elastin colocalize in the breast tumor stroma

The tumor microenvironment regulates tissue development and homeostasis, and its dysregulation contributes to neoplastic progression. Increased expression of type X collagen α‐1 (ColXα1) in tumor‐associated stroma correlates with poor pathologic response to neoadjuvant chemotherapy in estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2)‐positive breast cancers. Evaluation of ColXα1 expression patterns suggests a potential connection with elastin fibers. To investigate the possible interaction between ColXα1 and elastin, we evaluated the expression of ColXα1 in relation to elastin fibers in normal breast tissue, ductal carcinoma in situ, and invasive breast carcinomas at cellular and subcellular levels. Our findings demonstrate that ColXα1 colocalizes with elastin in invasive breast cancer‐associated stroma by immunohistochemistry, immunofluorescence, and electron microscopy. In 212 invasive breast carcinomas, this complex was aberrantly and selectively expressed in tumor extracellular matrix in 79% of ER+/HER2−, 80% of ER+/HER2+, 76% of ER−/HER2+, and 58% of triple negative breast cancers. In contrast, ColXα1 was generally absent, while elastin was present perivascularly in normal breast tissue. ColXα1 and elastin were coexpressed in 58% of ductal carcinoma in situ (DCIS) in periductal areas. In mass‐forming DCIS with desmoplastic stroma, the complex was intensely expressed in periductal areas as well as within the tumor‐associated stroma in all cases. Our data suggest that the breast carcinoma neoplastic process may involve aberrant expression of ColXα1 and elastin in the tumor microenvironment emerging early at the DCIS stage. Enrichment of these complexes in tumor‐associated stroma may represent a stromal signature indicative of intrinsic differences between breast cancers. These findings shed light on investigation into the role of aberrant collagen complex expression in tumorigenesis and tumor progression which may be leveraged in therapeutic and theranostic applications.

Invasive Lobular Carcinoma With Extracellular Mucin: Not All Mucinous Mammary Carcinomas Are Ductal!

Mucinous component in mammary carcinoma indicates ductal phenotype. Although intracytoplasmic mucin and signet ring cell change are frequently described with lobular carcinomas, extracellular mucin is not associated with lobular phenotype. We report 4 cases of invasive lobular carcinoma with extracellular mucin (ILCEM) and review findings of previously published cases of this rare ILC variant. Variable amount of extracellular mucin and pseudoglandular architectural pattern may lead to diagnosis of ILCEM as ductal mucinous carcinoma. Pathologists should be aware of this rare variant of ILC that will help identify more cases of this entity and clarify relevance of extracellular mucin production in ILC.

Large Epithelial and Stromal Lesion of Breast: It’s Not Always Phyllodes!

Fibroepithelial lesions (FELs) of breast often pose a diagnostic challenge to pathologists. In this article, we share gross and microscopic findings of 3 large breast lesions with epithelial and spindle cell components: (1) a giant fibroadenoma (FA; Figure 1 [1A-C]), (2) a borderline phyllodes tumor (World Health Organization classification; Figure 1 [2A-C]), and (3) a nodular pseudoangiomatous stromal hyperplasia (NPASH; Figure 1 [3A-C]). This brief report highlights histological overlap between NPASH and FELs, and describes morphological clues that can help pathologists in differentiating NPASH from FELs with PASH-like stroma. NPASH is an underrecognized entity, which is often misdiagnosed as FA. NPASH is a mass-forming lesion with circumscribed lesion-normal tissue interface. NPASH and conventional PASH have similar architectural and cytological features: myofibroblast-like spindle cells 805843 IJSXXX10.1177/1066896918805843International Journal of Surgical PathologyWawire et al research-article2018