Citations

Introduction: A 65-year-old male with type one diabetes mellitus underwent a pancreas and kidney transplant approximately seven years ago and has received chronic tacrolimus. He presented with subacute dyspnea on exertion, orthopnea, and edema. His background also includes ongoing chronic kidney disease stage 3A, orthostatic hypotension, and spinal stenosis. On exam, he had abdominal and lower extremity swelling. An echocardiogram showed preserved LVEF, concentric hypertrophy, hyperrefractile myocardium, reduced longitudinal strain with apical sparing, and a tiny pericardial effusion. Hypothesis: His echocardiogram indicated an infiltrative process such as amyloidosis or tacrolimus cardiotoxicity or possibly hypertrophic cardiomyopathy. Methods: Free light chains and protein studies with mass-fixation demonstrated no monoclonal gammopathy. PYP scan was negative for transthyretin amyloidosis. A cardiac MRI showed patchy subendocardial and midmyocardial delayed gadolinium enhancement, supporting the clinical suspicion for cardiac amyloidosis. With the need to exclude tacrolimus toxicity as well, subsequent endomyocardial biopsy revealed apolipoprotein A-IV-associated cardiac amyloidosis (Figure 1). Results: Apolipoprotein A-IV-associated cardiac amyloidosis occurs in about 0.6% of patients with cardiac amyloid and has classic manifestations of LV outflow obstruction, microvascular disease, and especially renal insufficiency. When these features occur in patients with clinical and imaging findings suggesting cardiac amyloidosis despite negative testing for more common types of amyloidosis, clinicians should proceed with endomyocardial biopsy to evaluate for less common forms. Conclusions: We report a rare case of apolipoprotein A-IV-associated cardiac amyloidosis. This case highlights the need for endomyocardial biopsy when clinical suspicion for cardiac amyloidosis persists despite negative testing.

Context.— Respiratory infections complicate lung transplantation and increase the risk of allograft dysfunction. Allograft lungs may have different susceptibilities to infection than native lungs, potentially leading to different disease severity in lungs of single lung transplant recipients (SLTRs). Objective.— To study whether infections affect allograft and native lungs differently in SLTRs but similarly in double LTRs (DLTRs). Design.— Using an institutional database of LTRs, medical records were searched, chest computed tomography studies were systematically reviewed, and histopathologic features were recorded per lung lobe and graded semiquantitatively. A multilobar-histopathology score (MLHS) including histopathologic data from each lung and a bilateral ratio (MLHSratio) comparing histopathologies between both lungs were calculated in SLTRs and compared to DLTRs. Results.— Six SLTRs died of infection involving the lungs. All allografts showed multifocal histopathologic evidence of infection, but at least 1 lobe of the native lung was uninvolved. In 4 of 5 DLTRs, histopathologic evidence of infection was seen in all lung lobes. On computed tomography, multifocal ground-glass and/or nodular opacities were found in a bilateral distribution in all DLTRs but in only 2 of 6 SLTRs. In SLTRs, the MLHSAllograft was higher than MLHSNative (P = .02). The MLHSratio values of SLTR and DLTR were significantly different (P < .001). Conclusions.— Allograft and native lungs appear to harbor different susceptibilities to infections. The results are important for the management of LTRs.

AimsGiant cell arteritis (GCA) is a systemic vasculitis affecting medium and large arteries in patients aged over 50 years. Involvement of temporal arteries (TA) can lead to complications such as blindness and stroke. While the diagnostic gold standard is temporal artery biopsy (TAB), comorbidities and age‐related changes can make interpretation of such specimens difficult. This study aims to establish a baseline of TA changes in subjects without GCA to facilitate the interpretation of TAB.Methods and resultsBilateral TA specimens were collected from 100 consecutive eligible postmortem examinations. Subjects were divided into four age groups and specimens semiquantitatively evaluated for eccentric intimal fibroplasia, disruption and calcification of the internal elastic lamina (IEL), medial attenuation and degree of lymphocytic inflammation of the peri‐adventitia, adventitia, media and intima. The individual scores of intimal fibroplasia, IEL disruption and medial attenuation were added to yield a ‘combined score (CS)’. Seventy‐eight 78 decedents were included in the final analysis following exclusion of 22 individuals for either lack of clinical information or inability to collect TA tissue. A total of 128 temporal artery specimens (50 bilateral from individual decedents, 28 unilateral) were available for examination. Intimal proliferation, IEL loss, IEL calcification and CS increased with age in a statistically significant fashion. Comparison of the oldest age group with the others showed statistically significant differences, although this was not uniformly preserved in comparison between the three youngest groups.ConclusionSenescent arterial changes and healed GCA exhibit histological similarity and such changes increase proportionally with age. The CS demonstrates significant association with age overall and represents a potential avenue for development to ‘normalise’ TA biopsies from older individuals.

Abstract Objectives Bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT) and sclerosing pneumocytoma (SP) are both rare and morphologically unique peripheral lung tumors with indolent behavior. These tumors have not been previously described as showing overlapping morphologic features and are generally genetically distinct. Methods Two cases were recently encountered that show hybrid morphologic features between BA/CMPT and SP, and the morphology and immunophenotype are described in detail. Results Both cases showed interstitial round cells typical of SP (TTF1+, EMA+), as well as areas more typical of BA/CMPT. One case showed BRAFV600E expression in the BA/CMPT areas but not in the SP-like cells. Conclusions Although it is possible that these cases represent collision tumors or are examples of unusual metaplastic epithelial changes in SP, they also raise the possibility that these 2 entities could occasionally coexist in true hybrid tumors.

Abstract Background Acute respiratory exacerbations in idiopathic pulmonary fibrosis (IPF), often triggered by infection, are life threatening events characterized by rapid deterioration of lung function and associated with poor prognosis. Since microbial antigens modulate immunity by activating different pattern recognition receptors (PRR) expressed by innate immune cells (including B-cells), we sought to investigate how the activation of human B-cells through PRR stimulation by different microbial (CpG and β-glucan) and non-microbial (Mitochondrial DAMPs; MTDs) antigens resulted in the release of an inflammatory/fibrotic milieu that contributed to the pathogenesis of fibrosis in patients with IPF. Results Our results show that an inflammatory milieu is induced by stimulating circulating B-cells with both noninfectious (MTDs) and infectious antigens (CpG and β-glucan) commonly found in bacteria and fungi. Moreover, we show that the inflammatory milieu produced was specific to the inducing antigen, and that the microbial antigens (CpG and β-glucan) triggered distinct signaling pathways in B-cells. Specifically, CpG induced mTOR-activation while β-glucan was mTOR-independent and activated Src and p38. Furthermore, our results also show that B-cell aggregates are present within fibrotic areas of the lung in IPF patients and activated B-cells induce fibroblast migration, which was modified by antifibrotics (nintedanib and pirfenidone). Conclusion Our results highlight the potential contribution of activated B-cells through PRRs to the proinflammatory and profibrotic milieu seen in patients with idiopathic pulmonary fibrosis.

Context.— Studies of lungs in patients with COVID-19 have focused on early findings. Objective.— To systematically study histopathologic and imaging features and presence of SARS-CoV-2 RNA in lung tissue from patients in later stages of COVID-19. Design.— Autopsies, explants, surgical lung biopsies, transbronchial biopsies, cryobiopsies, and needle biopsies from patients with COVID-19 whose onset of symptoms/confirmed diagnosis was more than 28 days before the procedure were studied. Available images were reviewed. Reverse transcription droplet digital polymerase chain reaction for SARS-CoV-2 RNA was performed on lung tissue. Results.— Of 44 specimens (43 patients; median age, 59.3 years; 26 [60.5%] male) features of acute lung injury (ALI) were seen in 39 (88.6%), predominantly organizing pneumonia and diffuse alveolar damage, up to 298 days after onset of COVID-19. Fibrotic changes were found in 33 specimens (75%), most commonly fibrotic diffuse alveolar damage (n = 22) and cicatricial organizing pneumonia (n = 12). Time between acquiring COVID-19 and specimen was shorter in patients with diffuse ALI (median, 61.5 days) compared with patients with focal (140 days) or no ALI (130 days) (P = .009). Sixteen (of 20; 80%) SARS-CoV-2 reverse transcription droplet digital polymerase chain reaction tests were positive, up to 174 days after COVID-19 onset. Time between COVID-19 onset and most recent computed tomography in patients with consolidation on imaging was shorter (median, 43.0 days) versus in patients without consolidation (87.5 days; P = .02). Reticulations were associated with longer time to computed tomography after COVID-19 onset (median, 82 versus 23.5 days; P = .006). Conclusions.— ALI and SARS-CoV-2 RNA can be detected in patients with COVID-19 for many months. ALI may evolve into fibrotic interstitial lung disease.

Abstract Objectives Differentiating malignant pleural mesothelioma from benign reactive mesothelial processes can be quite challenging. Ancillary tests such as BRCA1-associated protein 1 (BAP1) immunohistochemistry and p16 fluorescence in situ hybridization (FISH) are helpful tools to aid in this distinction. Immunohistochemistry for methylthioadenosine phosphorylase (MTAP) has recently been proposed as an effective surrogate marker for p16 FISH and is an attractive alternative test due to shorter turnaround time. There are little data regarding the specificity of MTAP loss for mesothelioma or whether it may be useful to distinguish mesothelioma from the most common entity in the differential diagnosis, sarcomatoid carcinoma. Methods We studied well-characterized cases of sarcomatoid carcinoma (n = 34) and sarcomatoid mesothelioma (n = 62), which were stained for MTAP (clone 2G4) and BAP1 (clone C-4). Results Loss of MTAP expression was observed in 17 (50%) of 34 pulmonary sarcomatoid carcinomas; BAP1 expression was retained in all of the cases in which it was performed (n = 31). MTAP expression was lost in 38 (61%) of 62 sarcomatoid mesotheliomas; BAP1 was lost in 6 (10%) of 62. In the six cases with BAP1 loss, five also had loss of MTAP, while MTAP expression was retained in one. Conclusions Loss of MTAP expression by immunohistochemistry is common in pulmonary sarcomatoid carcinoma, as it is present in half of cases. This rate is similar to what is observed in sarcomatoid mesothelioma (61%). Therefore, this stain is not useful to distinguish between these two malignancies. MTAP loss is more common than BAP1 loss in the setting of sarcomatoid mesothelioma (61% vs 10%, respectively).

Abstract B-cell activation is increasingly linked to numerous fibrotic lung diseases, and it is well known that aggregates of lymphocytes form in the lung of many of these patients. Activation of B-cells by pattern recognition receptors (PRRs) drives the release of inflammatory cytokines, chemokines, and metalloproteases important in the pathophysiology of pulmonary fibrosis. However, the specific mechanisms of B-cell activation in patients with idiopathic pulmonary fibrosis (IPF) are poorly understood. Herein, we have demonstrated that B-cell activation by microbial antigens contributes to the inflammatory and profibrotic milieu seen in patients with IPF. B-cell stimulation by CpG and β-glucan via PRRs resulted in activation of mTOR-dependent and independent pathways. Moreover, we showed that the B-cell–secreted inflammatory milieu is specific to the inducing antigen and causes differential fibroblast migration and activation. B-cell responses to infectious agents and subsequent B-cell–mediated fibroblast activation are modifiable by antifibrotics, but each seems to exert a specific and different effect. These results suggest that, upon PRR activation by microbial antigens, B-cells can contribute to the inflammatory and fibrotic changes seen in patients with IPF, and antifibrotics are able to at least partially reverse these responses.

Abstract Context. —Not uncommonly, a surgical pathologist will be requested to review excised material, with a clinical diagnosis of cancer, in which no malignancy can be identified. Often, sampling may be the issue. However, different nonneoplastic processes may mimic cancer clinically and not be recognized histologically. These are commonly referred to as pseudoneoplasms and can involve the lung, pleura, and mediastinum. Objective. —To review the most commonly encountered pseudoneoplasms of the thoracic cavity in surgical pathology and discuss the main differential diagnosis. Data Sources. —Literature and personal review of cases with focus on inflammatory pseudotumors of the lung, organizing pneumonia, nodular lymphoid hyperplasia, apical cap, round atelectasis, and sclerosing mediastinitis with its pulmonary counterpart, hyalinizing granuloma. Conclusions. —When reviewing specimens that appear nondiagnostic for malignancy, it is important to consider one of these pseudoneoplasms in the differential diagnosis as they may explain the clinical and radiologic information.

Abstract Context. —Diffuse pulmonary hemorrhage is an uncommon presenting manifestation of angiosarcoma. Objective. —To review the clinical, radiologic, and pathologic findings of patients with metastatic angiosarcoma who presented with diffuse pulmonary hemorrhage. Design. —Patients fulfilling inclusion criteria were identified from the consultation files. Clinical and radiologic data were obtained from referring pathologists. Histologic slides were reviewed in all patients. Results. —Our patients included 6 men and 1 woman, aged 31 to 73 years; 4 patients were younger than 40 years. Six patients presented with hemoptysis, and all had diffuse abnormalities on radiographic studies. Clinical considerations prior to biopsy included pulmonary hemorrhage syndrome (n = 2), acute respiratory failure (n = 1), and infection (n = 1). Metastatic disease was included in the differential diagnosis in only 1 patient. None had a diagnosis of malignancy prior to lung biopsy. All biopsies showed hemorrhage associated with atypical epithelioid and spindle cells, forming anastomosing vascular channels, distributed along and within lymphatics and arteries. Neoplastic cells were immunoreactive for factor VIII–related protein or CD31 in all cases for which special stains were available. Three patients with complete follow-up died of their disease. Primary sites were discovered in all 3 patients who underwent autopsy examination. Two tumors arose in the heart and 1 in the pelvic soft tissues. One additional patient had a likely primary site identified in the right atrium by cardiac ultrasound and was subsequently lost to follow-up. Conclusion. —Angiosarcoma should be included in the differential diagnosis of diffuse pulmonary hemorrhage, especially in young adults.