Ultrastructural Cardiac Pathology: The Wide (yet so very small) World of Cardiac Electron Microscopy.

Electron microscopy (EM) was a popular diagnostic tool in the 1970s and early 80s. With the adoption of newer, less expensive techniques, such as immunohistochemistry, the role of EM in diagnostic surgical pathology has dwindled substantially. Nowadays, even in academic centers, EM interpretation is relegated to renal pathologists and the handful of (aging) pathologists with experience using the technique. As such, EM interpretation is truly arcane-understood by few and mysterious to many. Nevertheless, there remain situations in which EM is the best or only ancillary test to ascertain a specific diagnosis. Thus, there remains a critical need for the younger generation of surgical pathologists to learn EM interpretation. Recognizing this need, cardiac EM was made the theme of the Cardiovascular Evening Specialty Conference at the 2023 United States and Canadian Academy of Pathology (USCAP) annual meeting in New Orleans, Louisiana. Each of the speakers contributed their part to this article, the purpose of which is to review EM as it pertains to myocardial tissue and provide illustrative examples of the spectrum of ultrastructural cardiac pathology seen in storage/metabolic diseases, cardiomyopathies, infiltrative disorders, and cardiotoxicities.

Arrhythmogenic Left Ventricular Mass as the Initial Presentation of Cardiac Sarcoidosis.

Cardiac tumors of the left ventricle are rare, and cardiac magnetic resonance is the preferred imaging tool for evaluation given superior tissue characterization. We present a case of a patient with arrhythmia and left ventricular mass that was ultimately diagnosed with cardiac sarcoidosis, reminding us that tissue is the issue.

Consensus statement on the processing, interpretation and reporting of temporal artery biopsy for arteritis.

Giant cell arteritis (GCA) is the most common systemic vasculitis in adults in Europe and North America, typically involving the extra-cranial branches of the carotid arteries and the thoracic aorta. Despite advances in noninvasive imaging, temporal artery biopsy (TAB) remains the gold standard for establishing a GCA diagnosis. The processing of TAB depends largely on individual institutional protocol, and the interpretation and reporting practices vary among pathologists. To address this lack of uniformity, the Society for Cardiovascular Pathology formed a committee tasked with establishing consensus guidelines for the processing, interpretation, and reporting of TAB specimens, based on the existing literature. This consensus statement includes a discussion of the differential diagnoses including other forms of arteritis and noninflammatory changes of the temporal artery.

Thoracic Aortic Aneurysm and Dissection: Review and Recommendations for Evaluation.

ABSTRACT: Aortic dissection and rupture (collectively termed "sudden aortic death") are commonly encountered by forensic pathologists, with an estimated incidence at autopsy between 0.6% and 7.7%. Despite this, there is no standard of practice for the evaluation of sudden aortic death at autopsy.Recent studies have shown 20% of patients with thoracic aortic aneurysm or dissection (TAAD) have an identifiable genetic syndrome, and 19% will have an affected first-degree relative. The past 2 decades have seen identification of new culprit genes and syndromes, which can have subtle or nonexistent external phenotypes. A high index of suspicion is warranted to identify possible hereditary TAAD (H-TAAD), allowing family members to obtain screening to avoid catastrophic vascular events. Forensic pathologists need broad knowledge of the spectrum of H-TAAD and awareness of the relative significance of hypertension, pregnancy, substance use, and microscopic changes of aortic architecture.This article reviews the common subtypes of H-TAAD, including Marfan syndrome, vascular Ehlers-Danlos, Loeys-Dietz, and familial thoracic aortic aneurysm and dissection. Recommendations for the evaluation of sudden aortic death at autopsy are presented, including (1) performance of a complete autopsy, (2) documentation of aortic circumference and valve morphology, (3) notifying family of the need for screening, and (4) preservation of a sample for potential genetic testing.

Histologic and Immunohistochemical Features of Antemortem Thrombus Compared to Postmortem Clot: Updating the Definition of Lines of Zahn.

CONTEXT.­: Distinguishing true antemortem thrombus (AMT) from artifactual postmortem clot (PMC) can occasionally be challenging at autopsy. Lines of Zahn are cited as pathognomonic of AMT, but review of literature reveals heterogeneous definitions of the term. Neutrophil karyorrhexis and CD61 immunohistochemistry can also be used to define AMT, but there has been no systematic study determining the specificity of these features. OBJECTIVE.­: To identify features that distinguish AMT from PMC, and to clarify the definition of lines of Zahn. DESIGN.­: PMC from the heart was collected in 50 hospital autopsies. Fifty arterial and 50 venous surgical thrombectomy specimens were reviewed for comparison. The microscopic features with hematoxylin-eosin staining, phosphotungstic acid-hematoxylin (PTAH) staining, and CD61 immunohistochemistry were documented. RESULTS.­: Thin curvilinear strands of fibrin and clumps of fibrin were frequently observed in both AMT and PMC. Thick bands of nested platelets wrapped in fibrin were nearly exclusive to AMT. Neutrophil karyorrhexis was readily apparent on low power in AMT but was seen in 40 of 50 PMCs (80%) only sparsely on high-power examination. Bone marrow elements were identified in 38 of 50 PMCs (76%). CD61 staining showed a geographic pattern in AMT and a speckled pattern in PMC. PTAH staining confirmed features seen with hematoxylin-eosin. CONCLUSIONS.­: Thin curvilinear strands of fibrin are found in both AMT and PMC and can be misinterpreted as lines of Zahn. We define lines of Zahn as thick bands formed by nested platelets wrapped in fibrin. Diffuse neutrophil karyorrhexis is common in AMT; in contrast, bone marrow elements are often seen in PMC.

Fetal Left Ventricular Apical Aneurysm Progressing to Dilated Cardiomyopathy Due to Glycogen Storage Disease.

Fetal dilated cardiomyopathy is a rare anomaly characterized by ventricular dilation and dysfunction. Its causes are diverse, and its outcomes are generally dismal. We describe a rare case of prenatally diagnosed left ventricular apical aneurysm that progressed rapidly to dilated cardiomyopathy. At age 2 months, the infant underwent heart transplantation. Pathologic examination of the explanted heart revealed that the cause of the dilated cardiomyopathy was glycogen storage disease. This case highlights the crucial roles of timely diagnosis, frequent close monitoring, and multidisciplinary care in achieving a successful postnatal outcome.

Differences in Aortic Histopathology in Patients Undergoing Valve Reimplantation Surgery for Various Clinical Syndromes.

OBJECTIVES: The study aims to investigate aortic histopathologic differences among patients undergoing aortic valve reimplantation, suggest different mechanisms of aortic root aneurysm pathogenesis, and identify factors associated with long-term success of reimplantation. METHODS: From 2006 to 2017, 568 adults who underwent reimplantation for repair of aortic root aneurysm, including patients with tricuspid aortic valves with no connective tissue disease (TAV/NoCTD, n = 314/568; 55.3%), bicuspid aortic valves (BAVs, n = 86/568; 15.1%), or connective tissue disease (CTD, n = 177/568; 31.2%), were compiled into three comparison groups. Patients with both BAV and CTD (n = 9/568; 1.6%) were omitted to increase study power. Patient records were analyzed retrospectively, focusing on pathology reports, which were available for 98.42% of patients, and were classified based on their descriptions of aortic tissue samples, primarily from the noncoronary sinus. Mean follow-up time available for patients was 2.97 years. RESULTS: Aortitis, medial fibrosis, and smooth muscle loss were more common histopathologic findings in patients with TAV/NoCTD than in patients with BAV and CTD (p < 0.05). Cystic medial degeneration was most often found in patients with CTD, then TAV/NoCTD, and least in BAV (p < 0.01). Increases in mucopolysaccharides were found more often in the BAV group than in the TAV/NoCTD and CTD groups (p < 0.01). There were no differences in the frequency of elastic laminae fragmentation/loss across these three groups. Among all patients, 1.97% (n = 11/559) had an unplanned reintervention on the aortic valve after reimplantation, but no significant demographic or histopathologic differences were identified. CONCLUSION: Despite some common histopathologic features among patients undergoing aortic valve reimplantation, there were enough distinguishing features among aortic tissue samples of TAV/NoCTD, BAV, and CTD patients to suggest that these groups develop root aneurysms by different mechanisms. No histopathologic features were able to predict the need for late reintervention on the aortic valve.

Association Between Atrial Uptake on Cardiac Scintigraphy With Technetium-99m-Pyrophosphate Labeled Bone-Seeking Tracers and Atrial Fibrillation.

BACKGROUND: Transthyretin cardiac amyloidosis (ATTR-CA) is an increasingly recognized disease, in which atrial fibrillation (AF) has been shown to be prevalent. Cardiac scintigraphy with technetium-99m-pyrophosphate (99mTc-PyP) labeled bone-seeking tracers is used to noninvasively make the diagnosis of ATTR-CA, based on ventricular myocardial uptake. Assessment of atrial wall uptake (AU) on 99mTc-PyP is currently not used in the clinical setting Methods: We analyzed a cohort of patients referred for 99mTc-PyP scan at a tertiary center to explore AU and associations between any and incident AF, ATTR-CA, and all-cause mortality. RESULTS: Among 580 patients included, 296 patients (51%) had a diagnosis of AF; 164 patients (28%) had scans consistent with ATTR-CA while 117 patients (20%) had AU. Of 117 patients with AU, 107 (91%) had any AF. In contrast, of 463 patients without AU 191(41%) had any AF. Of those with AU, 59/117(50%) patients had a 99mTc-PyP diagnosis of ATTR-CA while 58/117(50%) patients did not have such a diagnosis (P=1.00). Patients with AU had significantly more any AF (hazard ratio [HR], 1.03 [95% CI, 1.02-1.04]; P<0.001), independent of ATTR-CA diagnosis and sex. On multivariable Cox proportional hazards analyses adjusting for age, AU, ATTR-CA diagnosis, sex, smoking, hypertension, diabetes, left ventricular ejection fraction, and coronary artery disease, both age (HR, 1.03 [95% CI, 1.02-1.04]; P<0.0001) and AU (HR, 2.68 [95% CI, 2.11-3.41]; P<0.0001) were independently associated with the development of any AF. Freedom from incident AF at 1-year was significantly lower in patients with AU, both in patients with and without ATTR-CA respectively (HR, 2.27 [95% CI, 1.37-3.78]; P<0.0001 versus HR, 2.21 [95% CI, 1.46-3.34]; P<0.0001). CONCLUSIONS: In a consecutive cohort of patients undergoing 99mTc-PyP scans, 20% had AU, which was statistically associated with any AF, independently of ATTR-CA diagnosis and sex. AU was associated with significantly lower freedom from incident AF at 1-year. Overlooking AU on 99mTc-PyP scans could potentially miss an earlier disease manifestation, or an additional risk factor for any/incident AF.

Invasive Aortic Valve Endocarditis: Clinical and Tissue Findings From a Prospective Investigation.

BACKGROUND: Advanced aortic valve infective endocarditis (IE) with progression and destruction beyond the valve cusps-invasive IE-is incompletely characterized. This study aimed to characterize further the invasive disease extent, location, and stage and correlate macroscopic operative findings with microscopic disease patterns and progression. METHODS: A total of 43 patients with invasive aortic valve IE were prospectively enrolled from August 2017 to July 2018. Of these patients, 23 (53%) had prosthetic valve IE, 2 (5%) had allograft IE, and 18 (42%) had native aortic valve IE. Surgical findings and intraoperative photography were analyzed for invasion location, extent, and stage. Surgical samples were formalin fixed and analyzed histologically. The time course of disease and management were evaluated. RESULTS: Pathogens included Staphylococcus aureus in 17 patients (40%). Invasion predominantly affected the non-left coronary commissure (76%) and was circumferential in 15 patients (35%) (14 had prosthetic valves). Extraaortic cellulitis was present in 29 patients (67%), abscess in 13 (30%), abscess cavity in 29 (67%), and pseudoaneurysm in 8 (19%); 7 (16%) had fistulas. Histopathologic examination revealed acute inflammation, abscess formation, and lysis of connective tissue but not of myocardium or elastic tissue. Median time from onset of symptoms to antibiotics was 5 days, invasion confirmation 15 days, and surgery 37 days. Patients with S aureus had a 21-day shorter time course than patients non-S aureus. New or worsening heart block developed in 8 patients. CONCLUSIONS: Advanced invasive aortic valve IE demonstrates consistent gross patterns and stages correlating with histopathologic findings. Invasion results from a confluence of factors, including pathogen, time, and host immune response, and primarily affects the fibrous skeleton of the heart and expands to low-pressure regions.

Mitral annular calcification and valvular dysfunction: multimodality imaging evaluation, grading, and management.

Mitral annular calcification (MAC) refers to calcium deposition in the fibrous skeleton of the mitral valve. It has many cardiovascular associations, including mitral valve dysfunction, elevated cardiovascular risk, arrhythmias, and endocarditis. Echocardiography conventionally is the first-line imaging modality for anatomic assessment, and evaluation of mitral valve function. Cardiac computed tomography (CT) has demonstrated importance as an imaging modality for the evaluation and planning of related procedures. It also holds promise in quantitative grading of MAC. Currently, there is no universally accepted definition or classification system of MAC severity. We review the multimodality imaging evaluation of MAC and associated valvular dysfunction and propose a novel classification system based on qualitative and quantitative measurements derived from echocardiography and cardiac CT.

A Clinico-Pathologic Approach to the Differential Diagnosis of Pericardial Tumors.

PURPOSE OF REVIEW: Tumors of the pericardium are rare, but a wide variety of congenital, infectious, inflammatory, and neoplastic processes have been reported. Pericardial tumors can be categorized as non-neoplastic or neoplastic. Neoplastic lesions can be further divided into benign or malignant, with malignancies being either primary or secondary (metastatic). Clinical, radiographic, and pathologic features of the most common entities are discussed. RECENT FINDINGS: Metastatic neoplasms involving the heart and pericardium are far more common than primary pericardial neoplasms. Of primary pericardial malignancies, mesothelioma is the most common; notably, cytology of effusion fluid is relatively insensitive to the diagnosis. The prognosis for most malignancies of the pericardium, primary or secondary, is poor. Increasingly, clinically recognized diseases that involve the pericardium include Erdheim-Chester and IgG4-related disease. This article provides a comprehensive review of the most recent literature to develop a structured framework to the differential diagnosis of pericardial tumors.

Case report of isolated cardiac sarcoidosis presenting as hypertrophic obstructive cardiomyopathy-a clinical picture printed on lenticular paper.

BACKGROUND: Cardiac sarcoidosis (CS) is an inflammatory granulomatous process of the myocardium that can be asymptomatic or have several different clinical phenotypes. One of its rarely described presentations consists of hypertrophy of the septal myocardium, similar to hypertrophic cardiomyopathy (HCM). Isolated cardiac sarcoidosis that haemodynamically mimics hypertrophic obstructive cardiomyopathy (HOCM) has been rarely described in the literature. CASE SUMMARY: A 64-year-old Caucasian female previously diagnosed with non-critical aortic stenosis presented with pre-syncope, and echocardiography showed significant obstruction based on left ventricular outflow tract gradients, confirmed by cardiac magnetic resonance (CMR), concerning for a phenocopy of HCM. Septal myectomy was performed and pathology specimen revealed non-caseating granulomata consistent with cardiac sarcoidosis. She was started on oral corticosteroids and initial cardiac fluorodeoxyglucose positron emission tomography (FDG-PET) done after 1 month of treatment was negative. Repeat FDG-PET 15 months later, in the setting of haemodynamic decompensation, demonstrated diffuse FDG uptake in the myocardium without extra-cardiac involvement. DISCUSSION: Our case brings together two entities: isolated cardiac sarcoidosis and its presentation mimicking HOCM, which has been very rarely described in the literature. And it also shows the scenario of surgical pathology diagnosis of sarcoidosis that was not suspected by initial CMR or FDG-PET, despite adequate preparation, only appearing on repeat FDG-PET done 15 months later. Isolated cardiac sarcoidosis should remain a differential diagnosis for any non-ischaemic cardiomyopathy without a clear cause, despite imaging evidence of HCM.

Development of sacral/buttock retiform purpura as an ominous presenting sign of COVID-19 and clinical and histopathologic evolution during severe disease course.

Retiform purpura has been described as a relatively frequent cutaneous finding in patients with coronavirus disease 2019 (COVID-19). The etiology is hypothesized to be related to thrombotic vasculopathy based on lesional biopsy specimen findings, but the pathogenesis of the vasculopathy is not completely understood. Here, we present a case of a retiform purpuric patch on the sacrum/buttocks in a hospitalized patient prior to subsequent diagnosis of COVID-19 and an eventual fatal disease course. Two lesional biopsy specimens at different time points in the disease course revealed thrombotic vasculopathy, despite therapeutic anticoagulation. Detailed histopathologic evaluation using immunohistochemical markers suggest the etiology of the vasculopathy involves both persistent complement activation and platelet aggregation, which possibly promote ongoing thrombus formation. This case highlights that sacral/buttock retiform purpuric patches may be a presenting sign of infection with SARS-CoV-2 virus and may represent an ominous sign supporting a future severe disease course. In addition, biopsy specimen findings at separate time points demonstrate that cutaneous vasculopathy may persist despite adequate systemic anticoagulation, possibly due to the combination of persistent complement and platelet activation. Finally, occlusive thrombi in sacral/buttock retiform purpuric patches may contribute to future ulceration and significant cutaneous morbidity in patients who survive COVID-19.

Proteomics identifies a convergent innate response to infective endocarditis and extensive proteolysis in vegetation components.

Infective endocarditis is a life-threatening infection of heart valves and adjacent structures characterized by vegetations on valves and other endocardial surfaces, with tissue destruction and risk of embolization. We used high-resolution mass spectrometry to define the proteome of staphylococcal and non-staphylococcal vegetations and Terminal Amine Isotopic Labeling of Substrates (TAILS) to define their proteolytic landscapes. These approaches identified over 2000 human proteins in staphylococcal and non-staphylococcal vegetations. Individual vegetation proteomes demonstrated comparable profiles of quantitatively major constituents that overlapped with serum, platelet, and neutrophil proteomes. Staphylococcal vegetation proteomes resembled one another more than the proteomes of non-staphylococcal vegetations. TAILS demonstrated extensive proteolysis within vegetations, with numerous previously undescribed cleavages. Several proteases and pathogen-specific proteins, including virulence factors, were identified in most vegetations. Proteolytic peptides in fibronectin and complement C3 were identified as potential infective endocarditis biomarkers. Overlap of staphylococcal and non-staphylococcal vegetation proteomes suggests a convergent thrombotic and immune response to endocardial infection by diverse pathogens. However, the differences between staphylococcal and non-staphylococcal vegetations and internal variance within the non-staphylococcal group indicate that additional pathogen- or patient-specific effects exist. Pervasive proteolysis of vegetation components may arise from vegetation-intrinsic proteases and destabilize vegetations, contributing to embolism.

Sinus of Valsalva Aneurysms: A State-of-the-Art Imaging Review.

Cardiovascular imaging has an important role in the assessment and management of aortic root and thoracic aorta ectasia and aneurysms. Sinus of Valsalva aneurysms are rare entities. Unique complications associated with sinus of Valsalva aneurysms make them different from traditional aortic root aneurysms. Established guidelines on the diagnosis and management of sinus of Valsalva aneurysms are lacking. This article reviews the applications of multimodality cardiovascular imaging (echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging) for the dedicated assessment and imaging-guided management of sinus of Valsalva aneurysms.