HER2 testing in metastatic breast cancer - Is reflex ISH testing necessary on HER2 IHC-equivocal (2+) cases?

Current guidelines recommend HER2 testing on all primary invasive breast cancers and re-biopsy at disease relapse. The discordance rate between HER2-negative primaries and HER2 IHC2+ metastases that are ISH-amplified is unknown. We hypothesize that the majority of such cases are non-amplified. ISH testing is time-consuming and resource-intensive, and there may be situations where it is unnecessary. A retrospective review of IHC2+ metastatic lesions assessed with ISH at our center from 2013 to 2021 was undertaken. 105 cases were identified after exclusion of cases missing HER2 results, with primaries of unconfirmed origin, and cases of synchronous primary and metastatic disease. IHC and ISH results were recorded with detailed slide review of discordant cases. 91/105 metastases had HER2-negative primaries (87%). A metastasis was significantly more likely to be HER2-negative when the primary was HER2-negative (93%) versus positive (43%) (p < 0.0001). 54/91 primaries were IHC2+/ISH-non-amplified, and 50/54 (93%) corresponding metastases had identical results. Of the 37 HER2-negative primaries that were IHC0/1+, 35 (95%) corresponding metastases were ISH-non-amplified. Six metastases in cases with HER2-negative primaries were discordant. Characteristics of metastases suggesting ISH testing was warranted to assess for discordance included IHC heterogeneity, morphological discordance, increased staining of moderate intensity, and ER/PR discordance. One or more of these factors were present in all discordant metastases. Our results suggest selective ISH testing on HER2 IHC2+ breast cancer metastases in the context of HER2-negative primary disease may be appropriate when there is careful review of the IHC. Validation of our findings awaits further studies with larger sample sizes.

Age-related histologic features of the sinoatrial node from normal human hearts during the first 10 decades of life: a study of 200 cases.

Knowledge of the histologic constituency of the sinoatrial (SA) node is based on small studies with unevenly distributed ages and subjective assessments of nodal composition, leading to difficulties in interpreting what constitutes true pathology of the SA node. SA nodes from two-hundred normal hearts (10 male and 10 female from each of the first 10 decades of life) were digitally analyzed to assess their histologic composition. Both nodal area and nodal fat content (≥5%) showed a quadratic relationship with age, peaking in the fifth to eighth decades of life. Increased fat content was also more prevalent with increased BMI (≥25 kg/m2). No differences between sexes were observed. Mean nodal collagen ranged from 7.1% to 50.3%, without a statistically significant differences by age or body mass index (BMI). The data suggests that the designation of pathologic fibrosis should be reserved for SA nodes with >50% collagen content. These findings expand and refine our understanding of the anatomy of the SA node.

Increased mast cell density is associated with decreased fibrosis in human atrial tissue.

Fibrotic remodelling of the atria is poorly understood and can be regulated by myocardial immune cell populations after injury. Mast cells are resident immune sentinel cells present in the heart that respond to tissue damage and have been linked to fibrosis in other settings. The role of cardiac mast cells in fibrotic remodelling in response to human myocardial injury is controversial. In this study, we sought to determine the association between mast cells, atrial fibrosis, and outcomes in a heterogeneous population of cardiac surgical patients, including a substantial proportion of coronary artery bypass grafting patients. Atrial appendage from patients was assessed for collagen and mast cell density by histology and by droplet digital polymerase chain reaction (ddPCR) for mast cell associated transcripts. Clinical variables and outcomes were also followed. Mast cells were detected in human atrial tissue at varying densities. Histological and ddPCR assessment of mast cells in atrial tissue were closely correlated. Patients with high mast cell density had less fibrosis and lower severity of heart failure classification or incidence mortality than patients with low mast cell content. Analysis of a homogeneous population of coronary artery bypass graft patients yielded similar observations. Therefore, evidence from this study suggests that increased atrial mast cell populations are associated with decreased clinical cardiac fibrotic remodelling and improved outcomes, in cardiac surgery patients.

Global PD-L1 Signals and Tumor-Infiltrating Lymphocytes: Markers of Immunogenicity in Different Subsets of Merkel Cell Carcinoma and Potential Therapeutic Implications.

We previously studied the genetic and immunohistochemical profiles of subsets of Merkel cell carcinoma (MCC) stratified by morphology and Merkel cell polyomavirus (MCPyV) status. Recent advances in the immunotherapy of this disease prompted us to examine markers of immunogenicity [PD-L1 expression and tumor-infiltrating lymphocytes (TILS) in these subsets]. The observed clinical responses to checkpoint inhibition of the PD-1/PD-L1 pathway have not correlated with PD-L1 expression by MCC cells, and recent evidence suggests that functions of this pathway within the immune tumor microenvironment may be relevant. We conducted a semiquantitative (high, moderate, and minimal) immunohistochemical evaluation of the global PD-L1 signal in 52 cases of MCC, segregated in 3 subsets [pure MCPyV-positive (n = 28), pure MCPyV-negative (n = 9), and combined MCPyV-negative (n = 15)]. TILS were categorized as brisk, nonbrisk, or absent. Intersubset comparisons revealed that high global PD-L1 signals were exclusively associated with pure MCPyV-positive MCCs contrasted with virus-negative cases (P = 0.0003). Moderate signals were seen across all 3 groups. Brisk TILS were significantly associated with MCPyV-positive MCCs compared with MCPyV-negative cases (P = 0.029). Neither parameter (PD-L1 or TILS) was significantly different between the MCPyV-negative groups. Of potential clinical relevance, MCPyV seems to convey greater immunogenicity to MCCs than the high mutational burden/greater neoantigen load of MCPyV-negative cases. Interesting too is the fact that subset-related profiles of these markers mirrored those noted at genetic and immunohistochemical levels, separating pure MCPyV-positive MCCs from the virus-negative subsets.

Positron Emission Tomography/Computerized Tomography in Newly Diagnosed Patients with Giant Cell Arteritis Who Are Taking Glucocorticoids.

OBJECTIVE: Large vessel uptake on positron emission tomography/computerized tomography (PET/CT) supports the diagnosis of giant cell arteritis (GCA). Its value, however, in patients without arteritis on temporal artery biopsy and in those receiving glucocorticoids remains unknown. We compared PET/CT results in GCA patients with positive (TAB+) and negative temporal artery biopsies (TAB-), and controls. METHODS: Patients with new clinically diagnosed GCA starting treatment with glucocorticoids underwent temporal artery biopsy and PET/CT. Using a visual semiquantitative approach, 18F-fluorodeoxyglucose (FDG) uptake was scored in 8 vascular territories and summed overall to give a total score in patients and matched controls. RESULTS: Twenty-eight patients with GCA and 28 controls were enrolled. Eighteen patients with GCA were TAB+. Mean PET/CT scores after an average of 11.9 days of prednisone were higher in patients with GCA compared to controls, for both total uptake (10.34 ± 2.72 vs 7.73 ± 2.56; p = 0.001), and in 6 of 8 specific vascular territories. PET/CT scores were similar between TAB+ and TAB- patients with GCA. The optimal cutoff for distinguishing GCA cases from controls was a total PET/CT score of ≥ 9, with an area under the receiver-operating characteristic curve of 0.75, sensitivity 71.4%, and specificity 64.3%. Among patients with GCA, these measures correlated with greater total PET/CT scores: systemic symptoms (p = 0.015), lower hemoglobin (p = 0.009), and higher platelet count (p = 0.008). CONCLUSION: Vascular FDG uptake scores were increased in most patients with GCA despite exposure to prednisone; however, the sensitivity and specificity of PET/CT in this setting were lower than those previously reported.

Granulomas and giant cells in hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP) is an immunologically mediated form of diffuse lung disease, with histopathologic features that include cellular bronchiolitis, interstitial pneumonia, poorly formed granulomas, isolated multinucleated giant cells (MNGCs), organizing pneumonia, and interstitial fibrosis. This study describes the clinical and histopathologic findings in a retrospective series of 40 consecutive patients diagnosed with HP at the Mayo Clinic in Rochester, MN, between 1997 and 2011. Because the literature indicates that granulomas and MNGCs are located in the interstitium, particular attention was given to their distribution. Of the 40 patients, 33 underwent surgical lung biopsy and 7 underwent lung transplantation. Thirty-eight (95%) patients had interstitial pneumonia; 37 (93%), cellular bronchiolitis; 32 (80%), nonnecrotizing granulomas; 31 (78%), isolated MNGCs; 34 (85%) organizing pneumonia, and 31 (78%); interstitial fibrosis. In 27 cases, the granulomas were within airspaces; and in 26, they were interstitial. In 25 cases, MNGCs were within airspaces; and in 24, they were interstitial. In 3 (8%) cases, both granulomas and MNGCs were seen only within airspaces. Interstitial fibrosis was centrilobular in 22 cases, resembled usual interstitial pneumonia in 18 cases, and resembled nonspecific interstitial pneumonia in 11 cases. The "classic triad" of bronchiolitis, interstitial pneumonia, and granulomas was seen in 29 (73%) cases and was most frequent in biopsy than explant specimens (P = .004). This study confirms that granulomas and MNGCs are not confined to the pulmonary interstitium in HP.

PRKAR1A in the development of cardiac myxoma: a study of 110 cases including isolated and syndromic tumors.

Cardiac myxoma usually occurs as a solitary mass, but occasionally develops as part of a familial syndrome, the Carney complex (CNC). Two thirds of CNC-associated cardiac myxomas exhibit mutations in PRKAR1A. PRKAR1A mutations occur in both familial and sporadic forms of CNC but have not been described in isolated (nonsyndromic) cardiac myxomas. A total of 127 consecutive cardiac myxomas surgically resected at Mayo Clinic (1993 to 2011) from 110 individuals were studied. Clinical, radiologic, and pathologic findings were reviewed. Of these, 103 patients had isolated cardiac myxomas, and 7 patients had the tumor as a component of CNC. Age and sex distributions were different for CNC (mean 26 y, range 14 to 44 y, 71% female) and non-CNC (mean 62 y, range 18 to 92 y, 63% female) patients. PRKAR1A immunohistochemical analysis (IHC) was performed, and myxoma cell reactivity was graded semiquantitatively. Bidirectional Sanger sequencing was performed in 3 CNC patients and 29 non-CNC patients, to test for the presence of mutations in all coding regions and intron/exon boundaries of the PRKAR1A gene. IHC staining showed that all 7 CNC cases lacked PRKAR1A antigenicity and that 33 (32%) isolated cardiac myxomas were similarly nonreactive. Of tumors subjected to sequencing analysis, 2 (67%) CNC myxomas and 9 (31%) non-CNC myxomas had pathogenic PRKAR1A mutations. No germline mutations were found in 4 non-CNC cases tested. PRKAR1A appears to play a role in the development of both syndromic and nonsyndromic cardiac myxomas. Routine IHC evaluation of cardiac myxomas for PRKAR1A expression may be useful in excluding a diagnosis of CNC.

Venous invasion in oesophageal adenocarcinoma: enhanced detection using elastic stain and association with adverse histological features and clinical outcomes.

AIMS: In oesophageal adenocarcinoma, detection rates of venous invasion using haematoxylin and eosin (H&E) and elastic stains have not been compared. The aims of this study were to investigate whether or not elastic stains facilitate the detection of venous invasion, and to determine the prognostic significance of venous invasion following review with elastic stains. METHODS AND RESULTS: One hundred and three resection specimens containing oesophageal adenocarcinoma, all reported originally as negative for venous invasion, were examined for the presence of venous invasion using H&E and subsequently Movat pentachrome stains. Venous invasion was detected in eight cases with H&E and an additional 66 cases using Movat pentachrome; overall, 72% of cases contained venous invasion. Venous invasion was associated with advanced stage, tumour size, lymphatic and perineural invasion and subsequent distant metastases. Venous invasion, stage, size, grade, lymphatic invasion and perineural invasion were prognostically significant on univariate analysis. Only tumour stage was independently prognostic. Two of eight patients with venous invasion but no other indication for adjuvant treatment died of recurrent disease. CONCLUSIONS: Elastic stains improve detection of venous invasion significantly in oesophageal adenocarcinoma. Venous invasion is associated with multiple adverse clinicopathological features. Its identification may facilitate the stratification of patients at risk for visceral metastases and disease-related death.

Surgical pathology of atrial appendages removed during the cox-maze procedure: a review of 86 cases (2004 to 2005) with implications for prognosis.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Some patients are managed surgically (Cox-maze procedure) with removal of 1 or both atrial appendages. A retrospective review was performed on surgically excised atrial appendages from 86 consecutive patients with AF (2004 to 2005), at Mayo Clinic in Rochester, MN. These were compared with atrial appendages removed from 2 autopsy control groups without a history of AF (26 without heart disease, and 20 with heart disease). Compared with the 2 control groups, appendages from patients with AF contained more myocyte vacuolization, fatty infiltration, and myocardial inflammation. Among the AF patients, left atrial appendages (LAA) were larger and more likely to show fatty infiltration, endocardial fibroelastosis, and mural thrombus than were right atrial appendages (RAA); in contrast, RAA were more likely to show myocyte hypertrophy and interstitial fibrosis than were LAA. In the LAA, myocyte hypertrophy and interstitial fibrosis were more often seen in patients with long-term AF recurrence than were those who remained in normal sinus rhythm postoperatively (P=0.045 and 0.036, respectively). Given the potential clinical relevance of these findings, it is recommended that the presence or absence of hypertrophy and fibrosis, and their extent, be incorporated into the surgical pathology report of all patients undergoing resection of an atrial appendage.

Surgical pathology of native valve endocarditis in 310 specimens from 287 patients (1985-2004).

BACKGROUND: Few large studies have documented the clinical and pathologic features of native valve endocarditis (NVE) independently from prosthetic valve endocarditis (PVE). METHODS: A retrospective study of medical records of all patients undergoing operation for NVE at Mayo Clinic in Rochester, MN (1985-2004), was performed. Medical records were reviewed from 287 patients for demographics, infecting organism, and comorbidities. Microscopic slides from 310 valves were reviewed for features of infection. RESULTS: The study cohort included 287 patients, with age ranging from 9 to 87 years (mean, 54), yielding 310 valves. Most (73%) were from men, and 84% were regurgitant. Risk factors included bicuspid aortic valve (23%), dental manipulation (20%), mitral valve prolapse (18%), diabetes mellitus (16%), and others (<5% each); in 15%, no risk factor was identified. The four most commonly identified organisms were viridans group streptococci (28%), Staphylococcus aureus (18%), enterococci (9%), and coagulase-negative staphylococci (8%). NVE was histologically active in 58% and healed in 42%, and affected left-sided valves in 94%. It was associated with embolization in 29%, acute heart failure in 29%, and annular abscess in 18%. Men accounted for a higher percentage of aortic NVE than mitral NVE (82% versus 63%, respectively; P=.001). Among 126 valves with active endocarditis, 25% had no microorganisms identified histologically. CONCLUSION: NVE affected men nearly three times as frequently as women. Diabetes mellitus emerged as a prevalent (and previously underrecognized) risk factor for NVE. The most common infecting organisms were streptococci and staphylococci. Microorganisms were identified histologically in the majority of active endocarditis cases.