J. Jordi Rowe

Delay to formalin fixation ‘cold ischemia time’: effect on ERBB2 detection by in-situ hybridization and immunohistochemistry

The American Society of Clinical Oncology/College of American Pathologists ERBB2 testing guidelines address several pre-analytical variables known to affect ERBB2 testing accuracy. According to 2010 updated guidelines, the pre-analytical variable of time to tissue fixation (cold ischemia time) should be kept to <1 h, however, little has been published about cold ischemia time and its significance in ERBB2 testing. To that end, this study evaluated ERBB2 status using two different FDA-approved in-situ hybridization methods and an FDA-approved immunohistochemistry (IHC) assay in the largest cohort to date (n=84) of invasive breast carcinomas with tracked cold ischemia time. Cold ischemia time was stratified into four groups (<1 h (n=45), 1–2 h (n=27), 2–3 h (n=6), and >3 h (n=6)) and ERBB2 status was evaluated in each group by IHC (4B5) and by in-situ hybridization methodologies (PathVysion® fluorescence in situ hybridization and the INFORM HER2® dual in situ DNA probe assay). Both in-situ hybridization methods were evaluated using three ERBB2 scoring criteria (dual-probe guidelines, single-probe guidelines, and the FDA package insert scoring instructions). Fluorescence in-situ hybridization (FISH) and INFORM HER2® demonstrated 100% concordance in the detection of ERBB2 amplification by all three scoring guidelines at all cold ischemia time points. Agreement between in-situ hybridization methodologies and IHC was superior using single-probe guidelines compared with dual probe or FDA scoring instructions. In addition, Inform HER2® in-situ hybridization signals were significantly more intense than FISH at all cold ischemia time points, however, no significant loss of either chromosome 17 or ERBB2 signal was detected by FISH or Inform HER2® in-situ hybridization in cold ischemia times up to 3 h. On the basis of our findings, cold ischemia time up to 3 h has no deleterious effect on the detection of ERBB2 via in-situ hybridization or IHC.

Interobserver Variability by Pathologists in the Distinction Between Cellular Fibroadenomas and Phyllodes Tumors

Fibroepithelial lesions with cellular stroma are frequently termed cellular fibroadenomas although criteria for distinguishing them from a phyllodes tumor are vague and subjective. However, the clinical implications and surgical management for these 2 lesions may be different. We randomly selected 21 cases of fibroepithelial lesions sent in consultation to the senior author that were challenging to classify as cellular fibroadenoma or phyllodes tumor. One to 2 representative slides of each case along with patient age were sent to 10 pathologists who specialize in breast pathology. The World Health Organization criteria for phyllodes tumors and a diagnosis form were included with the study set. For the purposes of data reporting, fibroadenoma and cellular fibroadenoma are considered together. In only 2 cases was there uniform agreement as to whether the tumor represented a fibroadenoma or phyllodes tumor. Of the remaining 19 cases, if the diagnoses of fibroadenoma and benign phyllodes tumor were combined and separated from borderline and malignant phyllodes tumors, there was 100% agreement in 53% of cases and 90% agreement in 79% of cases. This study highlights the difficulty that exists in distinguishing some cellular fibroadenomas from phyllodes tumors even for pathologists who specialize in breast pathology. However, there appears to be considerable agreement when cellular fibroadenomas and benign phyllodes tumors are distinguished from borderline and malignant phyllodes tumors. Further studies are needed to determine if there is a clinically significant difference between cellular fibroadenomas and benign phyllodes tumors and how to better distinguish them from borderline and malignant phyllodes tumors.

Mitochondria-targeted nitroxides exacerbate fluvastatin-mediated cytostatic and cytotoxic effects in breast cancer cells.

Mito-CP11, a mitochondria-targeted nitroxide formed by conjugating a triphenylphosphonium cation to a five-membered nitroxide, carboxy-proxyl (CP), has been used as a superoxide dismutase (SOD) mimetic. In this study, we investigated the antiproliferative and cytotoxic properties of submicromolar levels of Mito-CP11 alone and in combination with fluvastatin, a well known cholesterol lowering drug, in breast cancer cells. Mito-CP11, but not CP or CP plus the cationic ligand, methyl triphenylphosphonium (Me-TPP+), inhibited MCF-7 breast cancer cell proliferation. Mito-CP11 had only minimal effect on MCF-10A, non-tumorigenic mammary epithelial cells. Mito-CP11, however, significantly enhanced fluvastatin-mediated cytotoxicity in MCF-7 cells. Mito-CP11 alone and in combination with fluvastatin inhibited nuclear factor kappa-B activity mainly in MCF-7 cells. We conclude that mitochondria-targeted nitroxide antioxidant molecules (such as Mito-CP11) that are non-toxic to non-tumorigenic cells could enhance the cytostatic and cytotoxic effects of statins in breast cancer cells. This strategy of combining mitochondria-targeted non-toxic molecules with cytotoxic chemotherapeutic drugs may be successfully used to enhance the efficacy of antitumor therapies in breast cancer treatment.

Genetic mapping of mammary tumor traits to rat chromosome 10 using a novel panel of consomic rats

Identification of novel breast cancer susceptibility and resistance genes in genetically diverse human populations is challenging, and so inbred rats have been used to identify novel mammary cancer susceptibility quantitative trait loci (QTLs) with conventional mapping approaches. An alternative approach for QTL mapping is to use chromosome substitution (consomic) rat strains, which has the advantage of rapid generation of congenic from consomic animals. Using a novel rat strain pair, SS and BN, we identified rat mammary cancer QTLs in one of two consomic rat strains tested. Female rats of inbred parental (SS and BN) and two consomic (SS-10 BN and SS-12 BN) strains were treated with 7,12-dimethylbenz[a]anthracene orally. The phenotypes of tumor incidence, latency, and multiplicity were evaluated. SS rats were highly susceptible to mammary adenocarcinoma development, whereas BN rats were completely resistant. Statistical comparison of the phenotypes between the susceptible parental and the two consomic strains identified QTLs residing within chromosome 10 controlling mammary tumor latency and multiplicity. The study shows that SS-BN consomic rat strains can be used to map mammary tumor QTLs. This novel approach should accelerate positional cloning of mammary cancer susceptibility and resistant genes in the rat and the identification of homologous genes in humans.

Mesenchymal tumours of the breast and their mimics: a review with approach to diagnosis

Mesenchymal tumours of the breast comprise a broad spectrum of entities that frequently pose diagnostic challenges to surgical pathologists. Metaplastic carcinoma and phyllodes tumour are site-specific mimics that account for the majority of tumours in the breast with a sarcomatoid appearance. Although uncommon, mammary tumours with fibroblastic, adipocytic or vascular differentiation may be encountered, spanning the spectrum from benign to malignant. Tumours with histiocytoid morphology are potential traps due to bland cytomorphology and resemblance to reactive processes. This comprehensive review provides a diagnostic approach to specific challenging mesenchymal tumours of the breast and their mimics, with a discussion on the salient morphological, immunohistochemical and molecular features that allow accurate diagnosis and will help the pathologist avoid potential pitfalls.

Metastatic malignant phyllodes tumor involving the cerebellum.

Brain metastases from malignant phyllodes tumors of the breast are a rare occurrence. We report a patient with a malignant phyllodes tumor of the right breast which subsequently metastasized to the right lower lobe of the lung 1 year after initial presentation, and to the right cerebellar hemisphere 2 years after diagnosis of her breast mass. After both chemotherapy and whole brain radiotherapy the patient is tumor free at most recent follow-up, 116 months after the breast tumor diagnosis was made. The literature is briefly reviewed and the differential diagnosis of malignant spindle cell brain tumors is discussed.

Dural-based Rosai–Dorfman disease: Differential diagnostic considerations

Extranodal sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) is a non-neoplastic condition that has rarely been reported to involve the central nervous system. This report documents a 28-year-old man with Rosai-Dorfman disease who presented with a seizure and a dural-based mass that was thought to represent a meningioma. Resection showed a lesion marked by large, S-100 protein immunoreactive histiocytic cells with intermixed benign lymphocytes and plasma cells. Emperipolesis with intracytoplasmic lymphocytes and plasma cells was present. Differential diagnostic considerations will be discussed.

Identification of novel carcinogen-mediated mammary tumor susceptibility loci in the rat using the chromosome substitution technique

We here report the genetic basis for susceptibility and resistance to carcinogen‐mediated [7,12‐dimethylbenz[a]anthracene (DMBA)] mammary tumorigenesis using the full panel of SS/BN consomic rat strains, in which substitutions of individual chromosomes from the resistant BN strain onto the genomic background of the susceptible SS strain were made. Analysis of 252 consomic females identified rat mammary Quantitative Trait Loci (QTLs) affecting tumor incidence on chromosomes 3 and 5, latency on chromosomes 3, 9, 14, and 19, and multiplicity on chromosomes 13, 16, and 19. In addition, we unexpectedly identified a novel QTL on chromosome 6 controlling a lethal toxic phenotype in response to DMBA. Upon further investigation with chromosomes 6 and 13 congenic lines, in which an additional 114 rats were investigated, we mapped (1) a novel mammary tumor QTL to a region of 27.1 Mbp in the distal part of RNO6, a region that is entirely separated from the toxicity phenotype, and (2) a novel and powerful mammary tumor susceptibility locus of 4.5 Mbp that mapped to the proximal q‐arm of RNO13. Comparison of genetic strain differences using existing rat genome databases enabled us to further construct priority lists containing single breast cancer candidate genes within the defined QTLs, serving as potential functional variants for future testing.

Radiation-associated angiosarcoma in the setting of breast cancer mimicking radiation dermatitis: A diagnostic pitfall†

We have encountered cases of post‐radiation angiosarcoma (PRAS) histologically mimicking radiation dermatitis.

Does Identifying Whether Pseudoangiomatous Stromal Hyperplasia (PASH) Is Focal or Diffuse on Core Biopsy Correlate With a PASH Nodule on Excision

Aims. Pseudoangiomatous stromal hyperplasia (PASH) diagnosed on core needle biopsy is generally excised. As a consequence, PASH as an incidental finding, may lead to unnecessary excisions. This study categorized PASH in biopsies as diffuse versus focal to determine if this correlates with the presence of a mass. Methods. In a 10-year period, 253 biopsies were identified and 159 met inclusion criteria. Of these, 47 biopsies had excisions. Biopsies and excisions were classified as diffuse, involving 2 adjacent lobules, or focal PASH in a single lobule or noncontiguous lobules. The diffuse or focal category on biopsy was correlated to the category on excision. Fibroadenomas with PASH were defined as concordant with diffuse PASH on biopsy. The category was correlated to the presence/absence of a mass determined from radiographic/clinical data for the 159 biopsies. Results. The biopsies were classified as diffuse (105, 66%) and focal (54, 34%). A total of 67% of biopsies with focal PASH showed either focal or no PASH on excision. Diffuse PASH on biopsy, had diffuse PASH in 93% of excisions. Concordance of this classification between biopsy and excision, using a Fisher’s exact test (2-tailed P value is <.0001), is statistically significant. A mass was present in 102/105 (97%) of biopsies with diffuse PASH. In biopsies with focal PASH, 78% had a mass lesion. Conclusions. Classification of diffuse versus focal PASH on biopsy was concordant with findings on excision. We found that diffuse PASH on biopsy showed strong correlation with a mass lesion. Quantifying PASH may assist with clinical-pathologic correlation and reduce unnecessary excisions.