Pathobiological Aspects Research Articles

Volumetric Integrated Classification Index: An Integrated Voxel-Based Morphometry and Machine Learning Interpretable Biomarker for Post-Traumatic Stress Disorder.

PTSD is a complex mental health condition triggered by individuals' traumatic experiences, with long-term and broad impacts on sufferers' psychological health and quality of life. Despite decades of research providing partial understanding of the pathobiological aspects of PTSD, precise neurobiological markers and imaging indicators remain challenging to pinpoint. This study employed VBM analysis and machine learning algorithms to investigate structural brain changes in PTSD patients. Data were sourced ADNI-DoD database for PTSD cases and from the ADNI database for healthy controls. Various machine learning models, including SVM, RF, and LR, were utilized for classification. Additionally, the VICI was proposed to enhance model interpretability, incorporating SHAP analysis. The association between PTSD risk genes and VICI values was also explored through gene expression data analysis. Among the tested machine learning algorithms, RF emerged as the top performer, achieving high accuracy in classifying PTSD patients. Structural brain abnormalities in PTSD patients were predominantly observed in prefrontal areas compared to healthy controls. The proposed VICI demonstrated classification efficacy comparable to the optimized RF model, indicating its potential as a simplified diagnostic tool. Analysis of gene expression data revealed significant associations between PTSD risk genes and VICI values, implicating synaptic integrity and neural development regulation. This study reveals neuroimaging and genetic characteristics of PTSD, highlighting the potential of VBM analysis and machine learning models in diagnosis and prognosis. The VICI offers a promising approach to enhance model interpretability and guide clinical decision-making. These findings contribute to a better understanding of the pathophysiological mechanisms of PTSD and provide new avenues for future diagnosis and treatment.

Updates in pathobiological aspects of anaplastic large cell lymphoma.

Anaplastic large cell lymphomas (ALCL) encompass several distinct subtypes of mature T-cell neoplasms that are unified by the expression of CD30 and anaplastic cytomorphology. Identification of the cytogenetic abnormality t(2;5)(p23;q35) led to the subclassification of ALCLs into ALK+ ALCL and ALK- ALCL. According to the most recent World Health Organization (WHO) Classification of Haematolymphoid Tumours as well as the International Consensus Classification (ICC) of Mature Lymphoid Neoplasms, ALCLs encompass ALK+ ALCL, ALK- ALCL, and breast implant-associated ALCL (BI-ALCL). Approximately 80% of systemic ALCLs harbor rearrangement of ALK, with NPM1 being the most common partner gene, although many other fusion partner genes have been identified to date. ALK- ALCLs represent a heterogeneous group of lymphomas with distinct clinical, immunophenotypic, and genetic features. A subset harbor recurrent rearrangement of genes, including TYK2, DUSP22, and TP63, with a proportion for which genetic aberrations have yet to be characterized. Although primary cutaneous ALCL (pc-ALCL) is currently classified as a subtype of primary cutaneous T-cell lymphoma, due to the large anaplastic and pleomorphic morphology together with CD30 expression in the malignant cells, this review also discusses the pathobiological features of this disease entity. Genomic and proteomic studies have contributed significant knowledge elucidating novel signaling pathways that are implicated in ALCL pathogenesis and represent candidate targets of therapeutic interventions. This review aims to offer perspectives on recent insights regarding the pathobiological and genetic features of ALCL.

Influenza C and D Viruses Demonstrated a Differential Respiratory Tissue Tropism in a Comparative Pathogenesis Study in Guinea Pigs.

Influenza C virus (ICV) is increasingly associated with community-acquired pneumonia (CAP) in children and its disease severity is worse than the influenza B virus, but similar to influenza A virus associated CAP. Despite the ubiquitous infection landscape of ICV in humans, little is known about its replication and pathobiology in animals. The goal of this study was to understand the replication kinetics, tissue tropism, and pathogenesis of human ICV (huICV) in comparison to the swine influenza D virus (swIDV) in guinea pigs. Intranasal inoculation of both viruses did not cause clinical signs, however, the infected animals shed virus in nasal washes. The huICV replicated in the nasal turbinates, soft palate, and trachea but not in the lungs while swIDV replicated in all four tissues. A comparative analysis of tropism and pathogenesis of these two related seven-segmented influenza viruses revealed that swIDV-infected animals exhibited broad tissue tropism with an increased rate of shedding on 3, 5, and 7 dpi and high viral loads in the lungs compared to huICV. Seroconversion occurred late in the huICV group at 14 dpi, while swIDV-infected animals seroconverted at 7 dpi. Guinea pigs infected with huICV exhibited mild to moderate inflammatory changes in the epithelium of the soft palate and trachea, along with mucosal damage and multifocal alveolitis in the lungs. In summary, the replication kinetics and pathobiological characteristics of ICV in guinea pigs agree with the clinical manifestation of ICV infection in humans, and hence guinea pigs could be used to study these distantly related influenza viruses. IMPORTANCE Similar to influenza A and B, ICV infections are seen associated with bacterial and viral co-infections which complicates the assessment of its real clinical significance. Further, the antivirals against influenza A and B viruses are ineffective against ICV which mandates the need to study the pathobiological aspects of this virus. Here we demonstrated that the respiratory tract of guinea pigs possesses specific viral receptors for ICV. We also compared the replication kinetics and pathogenesis of huICV and swIDV, as these viruses share 50% sequence identity. The tissue tropism and pathology associated with huICV in guinea pigs are analogous to the mild respiratory disease caused by ICV in humans, thereby demonstrating the suitability of guinea pigs to study ICV. Our comparative analysis revealed that huICV and swIDV replicated differentially in the guinea pigs suggesting that the type-specific genetic differences can result in the disparity of the viral shedding and tissue tropism.

Mice with humanized immune system as novel models to study HIV-associated pulmonary hypertension.

People living with HIV and who receive antiretroviral therapy have a significantly improved lifespan, compared to the early days without therapy. Unfortunately, persisting viral replication in the lungs sustains chronic inflammation, which may cause pulmonary vascular dysfunction and ultimate life-threatening Pulmonary Hypertension (PH). The mechanisms involved in the progression of HIV and PH remain unclear. The study of HIV-PH is limited due to the lack of tractable animal models that recapitulate infection and pathobiological aspects of PH. On one hand, mice with humanized immune systems (hu-mice) are highly relevant to HIV research but their suitability for HIV-PH research deserves investigation. On another hand, the Hypoxia-Sugen is a well-established model for experimental PH that combines hypoxia with the VEGF antagonist SU5416. To test the suitability of hu-mice, we combined HIV with either SU5416 or hypoxia. Using right heart catheterization, we found that combining HIV+SU5416 exacerbated PH. HIV infection increases human pro-inflammatory cytokines in the lungs, compared to uninfected mice. Histopathological examinations showed pulmonary vascular inflammation with arterial muscularization in HIV-PH. We also found an increase in endothelial-monocyte activating polypeptide II (EMAP II) when combining HIV+SU5416. Therefore, combinations of HIV with SU5416 or hypoxia recapitulate PH in hu-mice, creating well-suited models for infectious mechanistic pulmonary vascular research in small animals.

Comparative Pathobiology of Canine and Human Prostate Cancer: State of the Art and Future Directions.

Simple SummaryProstate cancer (PC) is one of the main types of cancer that affects the male population worldwide. In recent decades, there has been a significant evolution in the methods of diagnosis and treatment, mainly due to the development of new research in the field of molecular biology, allowing for a better understanding of how this cancer develops and progresses from a genetic point of view. In addition to humans, the canine is the only mammal that develops PC spontaneously. However, in dogs, PC has a distinct form, with high lethality rates. This work of scientific characterization of cancer in humans and dogs approaches how differences and similarities already all explain how PC develops and progresses in dogs, with a central tenet of molecular biology, that is, the transport between DNA, RNA and proteins. The understanding of these mechanisms makes it possible to identify new methods of the diagnosis and treatment of the disease, not only in men, but also in dogs.First described in 1817, prostate cancer is considered a complex neoplastic entity, and one of the main causes of death in men in the western world. In dogs, prostatic carcinoma (PC) exhibits undifferentiated morphology with different phenotypes, is hormonally independent of aggressive character, and has high rates of metastasis to different organs. Although in humans, the risk factors for tumor development are known, in dogs, this scenario is still unclear, especially regarding castration. Therefore, with the advent of molecular biology, studies were and are carried out with the aim of identifying the main molecular mechanisms and signaling pathways involved in the carcinogenesis and progression of canine PC, aiming to identify potential biomarkers for diagnosis, prognosis, and targeted treatment. However, there are extensive gaps to be filled, especially when considering the dog as experimental model for the study of this neoplasm in humans. Thus, due to the complexity of the subject, the objective of this review is to present the main pathobiological aspects of canine PC from a comparative point of view to the same neoplasm in the human species, addressing the historical context and current understanding in the scientific field.

Na+ homeostasis in Acinetobacter baumannii is facilitated via the activity of the Mrp antiporter.

The human opportunistic pathogen Acinetobacter baumannii is a global threat to healthcare institutions worldwide, since it developed very efficient strategies to evade host defence and to adapt to the different environmental conditions of the host. This work focused on the importance of Na+ homeostasis in A. baumannii with regards to pathobiological aspects. In silico studies revealed a homologue of a multicomponent Na+ /H+ antiporter system. Inactivation of the Mrp antiporter through deletion of the first gene (mrpA') resulted in a mutant that was sensitive to increasing pH values. Furthermore, the strain was highly sensitive to increasing Na+ and Li+ concentrations. Increasing Na+ sensitivity is thought to be responsible for growth impairment in human fluids. Furthermore, deletion of mrpA' is associated with energetic defects, inhibition of motility and survival under anoxic and dry conditions.

Current view on the issue of insufficient effectiveness of anti-VEGF therapy for age-related macular degeneration

Due to the significant medical and social importance of neovascular (wet) age-related macular degeneration (wAMD), increasing the effectiveness of anti-VEGF therapy used to treat this disease is one of the high-priority problems in modern retinology. This article focuses on pathobiological aspects and clinical manifestations of incomplete responses to anti-VEGF therapy of wAMD, considers the proposed ways to improve the terminology and classification of responses to therapy, as well as the assessment of its correctness and effectiveness of the treatment. It also discusses the available ways to optimize anti-VEGF therapy and define the criteria of its termination in cases when the treatment proves to be futile.

Review of TFEB-amplified renal cell carcinoma with focus on clinical and pathobiological aspects.

The disease entity of TFEB-amplified renal cell carcinoma (RCC) has been recently established. In this article, we review such cases. Clinically, the age of patients ranged from 28 to 83 years with a mean age of 62.8 years. The size of the tumor ranged from 1.9 to 19.5 cm with a mean size of 8.7 cm. The tumor demonstrated a variety of architectural patterns such as solid, alveolar, papillary, pseudopapillary, nested or tubular. The International Society of Urological Pathology (ISUP) grade usually corresponds to grade 3 or 4. Cytomorphology shows eosinophilic, clear, amphophilic or even oncocytic cytoplasm. Necrosis can be frequently observed. Neoplastic cells with TFEB-amplified RCC show diffuse or patchy positivity for TFEB. Fluorescence in situ hybridization frequently show the amplification of more than 10 or 20 copies of the TFEB gene. Most TFEB-amplified RCCs behave in an aggressive fashion. Metastasis frequently occurs. In conclusion, this tumor seems to be characterized by occurrence in older patients, frequent necrosis, papillary/pseudopapillary growth pattern, high-grade nuclear grade, TFEB gene amplification, and aggressive clinical behavior. In order to clarify whether this tumor is a distinct entity from previously described renal tumors or not, a further examination in a large scale study will be required in the future.

Histopathologic and Autopsy Findings in Patients Diagnosed With Coronavirus Disease 2019 (COVID-19): What We Know So Far Based on Correlation With Clinical, Morphologic and Pathobiological Aspects.

In response to the current outbreak of Coronavirus Disease-2019 (COVID-19), a fast body of literature emerged providing insights into the clinical and radiologic aspects of the novel disease, while the pathologic manifestations on tissue are yet to be sufficiently characterized mainly due to paucity of autopsy and biopsy of these cases. It is essential for both the clinicians and pathologists to maintain up-to-date knowledge of this continuously evolving topic in the midst of the current pandemic. Besides, understanding the impact of any disease in tissue pathology is crucial for better analysis of the pathogenesis and speculation of potential therapeutic targets. This review aimed to highlight the potential implication of COVID-19 in the pathology of various organ systems. We discuss the pathologic findings of the lungs, gastrointestinal tract, liver, brain, kidneys, heart, and the reproductive and immune systems that are associated with COVID-19. It seems that the respiratory, immune, and the digestive systems are the major targets of the disease. Mild mononuclear inflammatory cell infiltration is the most frequent histologic finding in general. Besides organ-specific changes, microthrombi, especially noticed in lungs, kidneys, and prostates, are the most significant observation microscopically. In addition, the possible mechanisms of organ injury were also reviewed.

The COVID-19 Pandemic during the Time of the Diabetes Pandemic: Likely Fraternal Twins?

An altered immune response to pathogens has been suggested to explain increased susceptibility to infectious diseases in patients with diabetes. Recent evidence has documented several immunometabolic pathways in patients with diabetes directly related to the COVID-19 infection. This also seems to be the case for prediabetic subjects with proinflammatory insulin resistance syndrome accompanied with prothrombotic hyperinsulinemic and dysglycemic states. Patients with frank hyperglycemia, dysglycemia and/or hyperinsulinemia develop systemic immunometabolic inflammation with higher levels of circulating cytokines. This deleterious scenario has been proposed as the underlying mechanism enhancing a cytokine storm-like hyperinflammatory state in diabetics infected with severe COVID-19 triggering multi-organ failure. Compared with moderately affected COVID-19 patients, diabetes was found to be highly prevalent among severely affected patients suggesting that this non-communicable disease should be considered as a risk factor for adverse outcomes. The COVID-19 pandemic mirrors with the diabetes pandemic in many pathobiological aspects. Our interest is to emphasize the ties between the immunoinflammatory mechanisms that underlie the morbidity and lethality when COVID-19 meets diabetes. This review brings attention to two pathologies of highly complex, multifactorial, developmental and environmentally dependent manifestations of critical importance to human survival. Extreme caution should be taken with diabetics with suspected symptoms of COVID-19 infection.

Top ten discoveries of the year: Neurooncology.

This article briefly discusses 10 topics that were selected by the author as top 10 discoveries published in 2019 in the broader field of neuro-oncological pathology (so including neurosciences as well as clinical neuro-oncology but with implications for neuro-oncological pathology). Some topics concern new information on immunohistochemical and molecular markers that enable improved diagnosis of particular tumors of the central nervous system (CNS) and information on a refined classification of medulloblastomas. Subsequently, several papers are discussed that further elucidate some pathobiological aspects of especially medulloblastomas (histogenesis, molecular evolution) and diffuse gliomas (mechanisms involved in CNS infiltration, role of cancer stem(-like) cells, longitudinal molecular evolution). The remaining topics concern progress made in vaccination therapy for glioblastomas and in using cerebrospinal fluid for liquid biopsy diagnosis of gliomas. Clearly, substantial, and sometimes even amazing progress has been made in increasing our understanding in several areas of neuro-oncological pathology. At the same time, almost every finding raises new questions, and translation of new insights in improving the outcome for patients suffering from CNS tumors remains a huge challenge.

Pretreatment Serum Levels of Soluble Cytokeratin Fragments (Cyfra 21-1, TPS, MonoTotal) in Relation to Clinical and Pathobiological Aspects of Head and Neck Squamous Cell Carcinomas.

The aim of this study was to analyze the pretreatment cytokeratin serum levels in head and neck squamous cell carcinoma (HNSCC) by three assays in relation to selected clinicopathological characteristics in an effort to find diagnostic/prognostic biomarkers for HNSCC and determine the best assay. In total, 46 patients with HNSCC with different subsite (oropharyngeal-21 cases, hypopharyngeal-4 and laryngeal-21) were included in this prospective study. MonoTotal, Cyfra 21-1, and TPS radioimmunoassay kits were used to analyze cytokeratin fragments serum levels. Statistically significant differences in serum levels of TPS and Cyfra 21-1 were found between low (stage I-II)- and high-stage (stage III-IV) tumors (p=0.0057; p=0.0138 respectively). Cyfra21-1 assay showed significant differences between tumors of different sites with prominent elevation being found in oropharyngeal carcinomas and between patients with p16 positive and p16 negative HNSCC (p=0.0242), being elevated in p16 positive tumors. The present study is the first to compare cytokeratin serum levels between various subgroups of HNSCC using three different assays. Cyfra 21-1 seems to be the most useful for clinical practice. The relation between elevated Cyfra 21-1 serum levels and p16 expression requires further investigation.

Persistent EcoHIV infection induces nigral degeneration in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-intoxicated mice

The widespread use of antiretroviral therapy for treatment of human immunodeficiency virus (HIV) infections has dramatically improved the quality and duration of life for HIV-positive individuals. Despite this success, HIV persists for the life of an infected person in tissue reservoirs including the nervous system. Thus, whether HIV exacerbates age-related brain disorders such as Parkinson's disease (PD) is of concern. In support of this idea, HIV infection can be associated with motor and gait abnormalities that parallel late-stage manifestations of PD including dopaminergic neuronal loss. With these findings in hand, we investigated whether viral infection could affect nigrostriatal degeneration or exacerbate chemically induced nigral degeneration. We now demonstrate an additive effect of EcoHIV on dopaminergic neuronal loss and neuroinflammation induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxication. HIV-1-infected humanized mice failed to recapitulate these EcoHIV results suggesting species-specific neural signaling. The results demonstrate a previously undefined EcoHIV-associated neurodegenerative response that may be used to model pathobiological aspects of PD.

A review ofALK-rearranged renal cell carcinomas with afocus on clinical and pathobiological aspects.

ALK-rearranged renal cell carcinoma (ALK-RCC) has been recently proposed and incorporated into therecent World Health Organisation Classification ofrenal tumours as aprovisional entity. Inthis article, we review ALK-RCC with afocus on clinical and pathobiological aspects. Seventeen cases have been described to date. ALK-RCC accounts for less than 1% ofall renal tumours. Theage ofpatients ranges from 6 to 61 years with amean age of29.6 years. Grossly, thetumour forms were ill-demarcated or well demarcated solid mass in therenal medulla. Histologically, RCC with VCL-ALK translocation resembles renal medullary carcinoma and mucinous cribriform pattern, signet-ring cell pattern and solid rhabdoid pattern are often observed in RCC with non-VCL-ALK fusion. Immunohistochemically, ALK protein diffusely expresses and TFE3 is often expressed. ALK gene can fuse to VCL, TPM3, EML4, HOOK1 or STRN gene. Abreak-apart fluorescence in situ hybridisation study is clinically available for thepractice ofdefinite diagnosis. ALK inhibitor therapy will provide great benefit for patients with advanced stage ofALK-RCC in thenear future.

Review of hereditary leiomyomatosis renal cell carcinoma with focus on clinical and pathobiological aspects of renal tumors.

The entity of hereditary leiomyomatosis renal cell carcinoma (HLRCC)-associated RCC has been proposed and integrated into the recent International Society of Urologic Pathology (ISUP) of renal tumors. This tumor is characterized by presence of cutaneous and/or uterine leiomyomas and RCC and autosomal dominant hereditary form. Grossly, HLRCC arising in the kidney show the solid tumor with frequent partial cystic area. Microscopically, the tumor typically shows papillary RCC, type 2, with eosinophilic large nucleoli reminiscent of cytomegaloviral inclusion and perinuclear clearing/haloes. Immunohistochemically, tumor cells show the overexpression for 2SC and reduced expression of FH. Germline mutation of fumarate hydratase (FH) gene, the HLRCC responsible gene mapped to chromosome 1q43, has been identified in patients with HLRCC. As the renal cancer in patients with HLRCC generally behave aggressively even in a small size, complete surgical resection and retroperitoneal lymph node resection should be performed promptly when the tumor is discovered. The surveillance of renal tumor in FH gene germline mutation-positive patients should be started from the early age using ultrasound sonography or magnetic resonance imaging.

Targeted Near-Infrared Fluorescence Imaging of Atherosclerosis: Clinical and Intracoronary Evaluation of Indocyanine Green

ObjectivesThis study sought to determine whether indocyanine green (ICG)–enhanced near-infrared fluorescence (NIRF) imaging can illuminate high-risk histologic plaque features of human carotid atherosclerosis, and in coronary atheroma of living swine, using intravascular NIRF-optical coherence tomography (OCT) imaging. BackgroundNew translatable imaging approaches are needed to identify high-risk biological signatures of atheroma. ICG is a U.S. Food and Drug Administration–approved NIRF imaging agent that experimentally targets plaque macrophages and lipid in areas of enhanced endothelial permeability. However, it is unknown whether ICG can target atheroma in patients. MethodsEight patients were enrolled in the BRIGHT-CEA (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque) trial. Five patients were injected intravenously with ICG 99 ± 25 min before clinically indicated carotid endarterectomy. Three saline-injected endarterectomy patients served as control subjects. Excised plaques underwent analysis by intravascular NIRF-OCT, reflectance imaging, microscopy, and histopathology. Next, following ICG intravenous injection, in vivo intracoronary NIRF-OCT and intravascular ultrasound imaged 3 atheroma-bearing coronary arteries of a diabetic, cholesterol-fed swine. ResultsICG was well tolerated; no adverse clinical events occurred up to 30 days post-injection. Multimodal NIRF imaging including intravascular NIRF-OCT revealed that ICG accumulated in all endarterectomy specimens. Plaques from saline-injected control patients exhibited minimal NIRF signal. In the swine experiment, intracoronary NIRF-OCT identified ICG uptake in all intravascular ultrasound–identified plaques in vivo. On detailed microscopic evaluation, ICG localized to plaque areas exhibiting impaired endothelial integrity, including disrupted fibrous caps, and within areas of neovascularization. Within human plaque areas of endothelial abnormality, ICG was spatially related to localized zones of plaque macrophages and lipid, and, notably, intraplaque hemorrhage. ConclusionsThis study demonstrates that ICG targets human plaques exhibiting endothelial abnormalities and provides new insights into its targeting mechanisms in clinical and experimental atheroma. Intracoronary NIRF-OCT of ICG may offer a novel, clinically translatable approach to image pathobiological aspects of coronary atherosclerosis. (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque [BRIGHT-CEA]; NCT01873716)

Review of succinate dehydrogenase-deficient renal cell carcinoma with focus on clinical and pathobiological aspects.

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) was first identified in 2004 and has been integrated into the 2016 WHO classification of RCC. Succinate dehydrogenase (SDH) is an enzyme complex composed of four protein subunits (SDHA, SDHB, SDHC and SDHD). The tumor which presents this enzyme mutation accounts for 0.05 to 0.2% of all renal carcinomas. Multiple tumors may occur in approximately 30% of affected patients. SDHB-deficient RCC is the most frequent, and the tumor histologically consists of cuboidal cells with eosinophilic cytoplasm, vacuolization, flocculent intracytoplasmic inclusion and indistinct cell borders. Ultrastructurally, the tumor contains abundant mitochondria. Immunohistochemically, tumor cells are positive for SDHA, but negative for SDHB in SDHB-, SDHC- and SDHD-deficient RCCs. However, SDHA-deficient RCC shows negativity for both SDHA and SDHB. In molecular genetic analyses, a germline mutation in the SDHB, SDHC or SDHD gene (in keeping with most patients having germline mutations in an SDH gene) has been identified in patients with or without a family history of renal tumors, paraganglioma/pheochromocytoma or gastrointestinal stromal tumor. While most tumors are low grade, some tumors may behave in an aggressive fashion, particularly if they are high nuclear grade, and have coagulative necrosis or sarcomatoid differentiation.

Review of renal cell carcinoma with rhabdoid features with focus on clinical and pathobiological aspects.

Rhabdoid morphology in renal cell carcinoma (RCC) may, like sarcomatoid change, be perceived as a type of dedifferentiation, and is a poor prognostic factor. Histologically, rhabdoid neoplastic cells are round to polygonal cells with globular eosinophilic cytoplasmic inclusions and eccentric vesicular nuclei and enlarged nucleoli. All types of RCC, including clear cell, papillary, chromophobe, collecting duct carcinoma, renal medullary carcinoma, acquired cystic disease-associated RCC, ALK-positive renal cancer and unclassified RCC, may display a variably prominent rhabdoid phenotype. Immunohistochemically, the cytoplasm of rhabdoid cells shows positivity for vimentin and/or cytokeratin. Ultrastructurally, cytoplasmic whorls/aggregates of intermediate filaments correspond to light microscopically observed inclusions. Genetically, a previous report suggests that combined loss of BAP1 and PBRM1 may be associated with rhabdoid morphology. As with sarcomatoid change, pathologists should describe, estimate and state the proportion of tumor cells with a rhabdoid phenotype in the routine pathology report of RCC.

Review of renal tumors associated with Birt-Hogg-Dubé syndrome with focus on clinical and pathobiological aspects.

Birt-Hogg-Dubé syndrome (BHDS) is an autosomal dominant inherited disorder characterized by clinical features of skin lesions, pulmonary lesions and renal tumor. The gene responsible for this syndrome is located on chromosome 17p11.2 and designated as FLCN. In this article, we review renal tumors associated with BHDS with a focus on clinical and pathobiological aspects. Renal tumors often occur multifocally or bilaterally in the imaging analyses or gross examination. Histological examination of renal tumors includes a variety of subtypes such as hybrid oncocytic tumor, chromophobe renal cell carcinoma (RCC), oncocytoma, clear cell RCC and papillary RCC. The histologic discordance in multiple tumors seems to be characteristic of this syndrome. Oncocytosis is observed histologically in about half of the cases. Several investigations have elucidated that folliculin may be involved in the mammalian target of rapamycin (mTOR) pathway recently. Renal tumors composed of clear cells may behave in an aggressive fashion. However, renal tumors including hybrid oncocytic tumor, chromophobe RCC and oncocytoma behave mostly in an indolent fashion.

Review of small cell carcinoma of the kidney with focus on clinical and pathobiological aspects.

Small cell carcinoma (SmCC) of the kidney is extremely rare. In this article, we present a review of SmCC of the kidney with the focus on clinical and pathobiological aspects. Macroscopically, this tumor often shows a bulky mass extensively replacing the renal parenchyma with vascular invasion and metastasis to lymph nodes. Histologically, the tumor is composed of small cells with scant cytoplasm, round to oval nuclei, finely granular chromatin and inconspicuous nucleoli. Rosette or tubular formation may be present. Immunohistochemically, neoplastic cells show variable positivity for neuron-specific enolase, chromogranin A, synaptophysin, CD57 (Leu7) and CD56. A dot-like staining pattern for cytokeratin may also be observed. An electron microscopic examination may identify electron-dense neurosecretory granules in the cytoplasm. As a therapeutic option, nephrectomy and systemic chemotherapy should be considered. However, despite multimodal therapy, most patients have a dismal outcome and die of widely metastatic disease within one to two years. As there are limited genetic data on SmCC of the kidney, a large series studying this will be needed in the future.