Pleura revisited: From histology and pathophysiology to pathology and molecular biology

Inflammation of the Pleural Cavity: A Review on Pathogenesis, Diagnosis and Implications in Tumor Pathophysiology

Simple Summary

The pleura is a cavity whose pathology ranges from simple fluid accumulation to tumor development, all inducing important consequences in patents health, and usually having an important association with local inflammation. Understanding the pathophysiology of pleural inflammation helps the development of the correct treatment strategies and opens new windows in pleural research. Thus, the aim of this review is to present the etiologies and the pathophysiological mechanisms of pleural inflammation with a special interest in their role on tumor development and diagnosis.

Abstract

Pleural effusions are a common respiratory condition with many etiologies. Nonmalignant etiologies explain most pleural effusions and despite being nonmalignant, they can be associated with poor survival; thus, it is important to understand their pathophysiology. Furthermore, diagnosing a benign pleural pathology always harbors the uncertainty of a false-negative diagnosis for physicians and pathologists, especially for the group of non-specific pleuritis. This review aims to present the role of the inflammation in the development of benign pleural effusions, with a special interest in their pathophysiology and their association with malignancy.

Adenomatoid tumours of the gastrointestinal tract - a case-series and review of the literature

AIMS

Adenomatoid tumours are mesothelial-derived benign neoplasms with a predilection for the genital tract. Extragenital sites are rare and can cause significant diagnostic challenges. Herein, we describe the clinicopathological features of a cohort of adenomatoid tumours involving the gastrointestinal tract and liver in order to more clearly characterise their histological findings and aid in diagnosis.

METHODS AND RESULTS

The pathology databases at four institutions were searched for adenomatoid tumours involving the gastrointestinal tract or liver, yielding eight cases. Available clinicoradiological and follow-up data were collected from the medical records. Six tumours were incidentally discovered during imaging studies or at the time of surgical exploration for unrelated conditions; presenting symptoms were unknown in two patients. Histologically, the tumours were well-circumscribed, although focal ill-defined borders were present in four cases. No infiltration of adjacent structures was identified. Architectural heterogeneity was noted in five (63%) tumours; an adenoid pattern often predominated. The neoplastic cells were flattened to cuboidal with eosinophilic cytoplasm. Cytoplasmic vacuoles mimicking signet ring-like cells were present in five (63%) cases. Three (38%) cases showed involvement of the mesothelium with reactive mesothelial hyperplasia. Cytological atypia or increased mitotic activity was not identified. The surrounding stroma ranged from oedematous/myxoid to densely hyalinised. Immunohistochemistry confirmed mesothelial origin in all cases evaluated. No patients developed recurrence of disease.

CONCLUSIONS

The current study evaluates the clinicopathological findings in a collective series of gastrointestinal and hepatic adenomatoid tumours, correlating with those described in individually reported cases. We highlight common histological features and emphasise variable findings that could mimic a malignant neoplasm.

STAT6 and phosphorylated STAT6 are differentially expressed in lymphomas

BACKGROUND

The STAT6 pathway is implicated in the pathogenesis of various lymphomas; however, its immunohistochemical expression has not been fully investigated. Thus, the aim of this study was to investigate the immunohistochemical expression of the two forms of STAT6, phosphorylated or not, in a series of systemic lymphomas.

MATERIALS AND METHODS

Immunohistochemical expression of two antibodies, STAT6 (clone YE361) and pSTAT6 (clone Y641), which recognise the phosphorylated form of the molecule was studied in 60 lymphomas.

RESULTS

STAT6^YE361 expression was cytoplasmic, with 23.3% of the cases showing high expression. pSTAT6^Y641 expression was mostly nuclear and found in 45% of the cases. pSTAT6^Y641 nuclear expression was associated with the lymphoma type (p < 0.0001), as it was seen mostly in follicular, Hodgkin and angioimmunoblastic T cell lymphomas. STAT6^YE361 cytoplasmic expression was also associated with lymphoma type (p = 0.001), as it was mostly found in diffuse large B cell and marginal B cell lymphomas. No association with PD-L1 expression, other clinicopathological data or prognosis was found.

CONCLUSION

The two STAT6 clones are differentially expressed between lymphoma types.

Pleural hemangioma: A case report and review of the literature

A middle-aged female with history of multinodular goiter, Hashimoto disease, and chronic vitamin B12 deficiency presented with palpitations and subsequent exertional dyspnea. Initial radiographic analysis suggested mediastinal cavernous hemangioma, but biopsy showed features consistent with pleural hemangioma. Pleural hemangioma should be considered among the differential diagnoses for recurrent unilateral pleural effusion. Pleural hemangioma should be distinguished from other more common entities including the similarly benign pulmonary hemangioma and the more aggressive pleural hemangioendothelioma.

Expression of STAT6 and Phosphorylated STAT6 in Primary Central Nervous System Lymphomas

The signal transducer and activator of transcription 6 (STAT6) is implicated in the pathogenesis of some lymphomas including primary central nervous system lymphomas (PCNSLs). The aim of this study was to investigate STAT6 expression and clinicopathologic features in 25 PCNSLs using immunohistochemistry with 2 different anti-STAT6 antibodies. One (YE361) recognizes the C-terminus domain of the STAT6 protein and the other (Y641) recognizes the phosphorylated form of the protein. The phosphorylated STAT6 form was not expressed in any of the cases studied whereas the YE361 STAT6 showed only cytoplasmic expression in 14 (56%) cases. This expression did not correlate with age, prognostic score, multiplicity, invasion of deep structures, response to treatment, disease recurrence, overall survival, or BCL6, BCL2, PD-L1, and CD8 expression. A STAT6 expression score showed a trend for correlating with clinical performance status. It also showed a positive correlation with MYC expression. Thus, the phosphorylated form of STAT6 was not found in the current series, while the YE361 STAT6 showed only cytoplasmic expression and was associated with expression of MYC.

Mesothelial Cysts

OBJECTIVES

Peritoneal mesothelial cysts have been reported under various terms, including benign cystic mesothelioma, usually in the form of case reports/series, whereas extraperitoneal cases are rarely reported. Our objective was to report the detailed characteristics of cystic lesions of the serosal cavities.

METHODS

We retrospectively examined the clinicopathologic findings of a series of mesothelial cystic lesions (n = 79).

RESULTS

Most cases (n = 68, 86%) concerned the peritoneum, whereas 11 (14%) concerned the pericardium. No pleural cases were found. A total of 51 (64.5%) lesions were solitary, whereas 28 (35.5%) were multiple. Peritoneal lesions harbored a plump eosinophilic mesothelium and a loose connective stroma, whereas pericardial lesions showed a cuboidal/flattened mesothelium, collagenous stroma, intense inflammation, and other tissue types, like adipose and muscle tissue. Solitary peritoneal lesions are usually extrapelvic and found in older patients incidentally during other surgeries, whereas multiple lesions are found in younger patients and usually in the pelvis. The lesions show a benign clinical course with rare recurrences but no malignant transformation.

CONCLUSIONS

Most mesothelial cysts are peritoneal and rarely pericardial. Peritoneal cysts differ from pericardial cysts. Peritoneal solitary lesions differ from multiple lesions, also suggesting their pathogenetic differences.

STAT6: A review of a signaling pathway implicated in various diseases with a special emphasis in its usefulness in pathology

Signal Transducer and Activator of Transcription 6 (STAT6), belonging to a family of seven similar members is primarily stimulated by interleukin(IL)-4 and IL-13, and acts as a T helper type 2 (Th2)-inducing factor. Thus, it is implicated in the pathophysiology of various allergic conditions, such as asthma, atopic dermatitis, eosinophilic esophagitis and food allergies, but also in tumor microenvironment regulation. Furthermore, certain forms of lymphomas, notably the Hodgkin lymphoma group, the primary mediastinal and primary central nervous system lymphoma, as well as some follicular and T cell lymphomas are associated with dysregulation of the STAT6 pathway. STAT6 immunohistochemical expression also serves as a surrogate marker in the diagnosis of solitary fibrous tumor, despite not directly responsible for the tumorigenic effect. These pathophysiological implications of the STAT6 pathway, its diagnostic or prognostic role in pathology, as well its immunohistochemical detection with different antibodies will be discussed in this review.

Medical artificial intelligence readiness scale for medical students (MAIRS-MS) - development, validity and reliability study

BACKGROUND

It is unlikely that applications of artificial intelligence (AI) will completely replace physicians. However, it is very likely that AI applications will acquire many of their roles and generate new tasks in medical care. To be ready for new roles and tasks, medical students and physicians will need to understand the fundamentals of AI and data science, mathematical concepts, and related ethical and medico-legal issues in addition with the standard medical principles. Nevertheless, there is no valid and reliable instrument available in the literature to measure medical AI readiness. In this study, we have described the development of a valid and reliable psychometric measurement tool for the assessment of the perceived readiness of medical students on AI technologies and its applications in medicine.

METHODS

To define medical students' required competencies on AI, a diverse set of experts' opinions were obtained by a qualitative method and were used as a theoretical framework, while creating the item pool of the scale. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were applied.

RESULTS

A total of 568 medical students during the EFA phase and 329 medical students during the CFA phase, enrolled in two different public universities in Turkey participated in this study. The initial 27-items finalized with a 22-items scale in a four-factor structure (cognition, ability, vision, and ethics), which explains 50.9% cumulative variance that resulted from the EFA. Cronbach's alpha reliability coefficient was 0.87. CFA indicated appropriate fit of the four-factor model (χ2/df = 3.81, RMSEA = 0.094, SRMR = 0.057, CFI = 0.938, and NNFI (TLI) = 0.928). These values showed that the four-factor model has construct validity.

CONCLUSIONS

The newly developed Medical Artificial Intelligence Readiness Scale for Medical Students (MAIRS-MS) was found to be valid and reliable tool for evaluation and monitoring of perceived readiness levels of medical students on AI technologies and applications. Medical schools may follow 'a physician training perspective that is compatible with AI in medicine' to their curricula by using MAIRS-MS. This scale could be benefitted by medical and health science education institutions as a valuable curriculum development tool with its learner needs assessment and participants' end-course perceived readiness opportunities.

Etiological Distribution and Morphological Patterns of Granulomatous Pleurisy in a Tuberculosis-prevalent Country

The cause of epithelioid granulomatous inflammation varies widely depending on the affected organ, geographic region, and whether the granulomas morphologically contain necrosis. Compared with other organs, the etiological distribution and morphological patterns of pleural epithelioid granulomas have rarely been investigated. We evaluated the final etiologies and morphological patterns of pleural epithelioid granulomatous inflammation in a tuberculosis (TB)-prevalent country. Of 83 patients with pleural granulomas, 50 (60.2%) had confirmed TB pleurisy (TB-P) and 29 (34.9%) had probable TB-P. Four patients (4.8%) with non-TB-P were diagnosed. With the exception of microbiological results, there was no significant difference in clinical characteristics and granuloma patterns between the confirmed TB-P and non-TB-P groups, or between patients with confirmed and probable TB-Ps. These findings suggest that most pleural granulomatous inflammation (95.2%) was attributable to TB-P in TB-endemic areas and that the granuloma patterns contributed little to the prediction of final diagnosis compared with other organs.

Adenomatoid Tumor: A Review of Pathology With Focus on Unusual Presentations and Sites, Histogenesis, Differential Diagnosis, and Molecular and Clinical Aspects With a Historic Overview of Its Description

Adenomatoid tumors have been described almost a century ago, and their nature has been the subject of debate for decades. They are tumors of mesothelial origin usually involving the uterus, the Fallopian tubes, and the paratesticular region. Adenomatoid tumors of the adrenal gland, the liver, the extragenital peritoneum, the pleura, and the mediastinum have been rarely reported. They are usually small incidental findings, but large, multicystic and papillary tumors, as well as multiple tumors have been described. Their pathogenesis is related to immunosuppression and to TRAF7 mutations. Despite being benign tumors, there are several macroscopic or clinical aspects that could raise diagnostic difficulties. The aim of this review was to describe the microscopic and macroscopic aspects of adenomatoid tumor with a special focus on its differential diagnosis and pathogenesis and the possible link of adenomatoid tumor with other mesothelial lesions, such as the well-differentiated papillary mesothelioma and the benign multicystic mesothelioma, also known as multilocular peritoneal cysts.

Facial nerve palsy in giant-cell arteritis: case-based review

Acute peripheral facial nerve palsy is most frequently idiopathic (Bell's palsy) or virally induced, but can also be due to several other conditions. A rare cause is underlying systemic or autoimmune disease. A 79-year-old man presented with peripheral facial nerve palsy, malaise, and fever. Physical examination revealed tenderness of the left temporal artery and reduced pulsatility. ¹⁸F-FDG-PET/CT and biopsy of the temporal artery confirmed the diagnosis of giant cell arteritis (GCA). Prompt institution of corticosteroid therapy produced rapid decrease in inflammatory markers and gradual improvement of the facial nerve palsy. We searched the MEDLINE, Embase, and Scopus databases to identify previous reports of peripheral nerve palsy in GCA, other vasculitides, and autoimmune diseases. Facial nerve palsy as the presenting symptom of GCA has very rarely been reported. Although temporal artery biopsy is the gold standard for diagnosis, it may be negative in up to one-third of cases. In doubtful cases, imaging can help establish the diagnosis. Ultrasound, 3 T MRI, and ¹⁸F-FDG-PET/CT have all been previously reported to be useful. Peripheral facial nerve palsy may very rarely be the presenting symptom of GCA. Early correct diagnosis is essential for starting appropriate therapy. In patients with atypical features, ¹⁸F-FDG-PET/CT may be useful for establishing the diagnosis.

Optimization of a Luciferase-Expressing Non-Invasive Intrapleural Model of Malignant Mesothelioma in Immunocompetent Mice

Malignant Pleural Mesothelioma (MPM) is an aggressive tumor of the pleural lining that is usually identified at advanced stages and resistant to current therapies. Appropriate pre-clinical mouse tumor models are of pivotal importance to study its biology. Usually, tumor cells have been injected intraperitoneally or subcutaneously. Using three available murine mesothelioma cell lines with different histotypes (sarcomatoid, biphasic, epithelioid), we have set up a simplified model of in vivo growth orthotopically by inoculating tumor cells directly in the thorax with a minimally invasive procedure. Mesothelioma tumors grew along the pleura and spread on the superficial areas of the lungs, but no masses were found outside the thoracic cavity. As observed in human MPM, tumors were highly infiltrated by macrophages and T cells. The luciferase-expressing cells can be visualized in vivo by bioluminescent optical imaging to precisely quantify tumor growth over time. Notably, the bioluminescence signal detected in vivo correctly matched the tumor burden quantified with classical histology. In contrast, the subcutaneous or intraperitoneal growth of these mesothelioma cells was considered either non-representative of the human disease or unreliable to precisely quantify tumor load. Our non-invasive in vivo model of mesothelioma is simple and reproducible, and it reliably recapitulates the human disease.

Clinical long-term outcome of non-specific pleuritis (NSP) after surgical or medical thoracoscopy

Background

Thoracoscopy, either “medical” or “surgical”, is the gold standard to reveal the cause of pleural effusion by taking large biopsies. However, in some cases, the histology of pleural biopsies is inconclusive for a specific cause, describing a variable process of inflammation, encompassing for non-specific pleuritis (NSP). Questions are raised whether the surgical (or video-assisted thoracoscopic surgery, VATS) is doing better than the medical thoracoscopy (MT or pleuroscopy), but no direct comparison between the two techniques exist in the current bibliography. The aim of our retrospective study was to compare these two techniques to find whether there is any difference in the false negative cases of NSP.

Methods

We included in our study 295 patients with NSP, 179 patients who underwent VATS comparing to 116 patients who underwent MT for pleural effusion of initially undetermined cause, having a follow-up of at least one year. Analysis of patients’ files, history, clinical examinations, further tests, and follow-up were recorded.

Results

The mean age of our patients was 58.5±19.1 and M/F gender was 216/79; no difference was observed between the two groups. The mean follow-up period was 47.3±20.7 months. After VATS, only one patient (0.55%) was finally diagnosed with pleural malignancy (false negative) while after MT 2 patients (1.7%). Negative predictive value for pleura-related malignancy for VATS was 0.994 and for MT 0.982.

Conclusions

In patients with histological diagnosis of NSP both VATS and MT showed similar and excellent results of false negative cases and negative predictive value in excluding malignant pleural disease.

Overview, Challenges and Future Prospects of Drug Information Services in Nepal: A Reflective Commentary

Drug information center (DIC) or Medicine information services provides impartial, well-referenced, critically evaluated, updated information on various aspects of medications to healthcare professionals and consumers. Medicine information services also contribute to the minimization of medication errors by promoting medication education and supporting pharmaceutical services. The main objective of this reflective commentary is to highlight the recent scenario of medicine information services in Nepal, challenges for DIC, how DICs can be strengthened and future perspectives of DIC. The availability of medicine information in various online drug information sites and numerous applications (apps) have made it easier to assess the information in the country such as Nepal. However, the reliability and validity of such information should be considered before dissemination. DIC plays a crucial role in improving drug safety by aiding clinicians in safer use of medications and promoting adverse drug reaction (ADR) reporting in Nepal. Financial support for operating the DIC efficiently is scarce in Nepal resulting in operational problems. The performance of the medicine information services in the country should be evaluated periodically to ensure the good quality of the service. Steps should be taken by the government, private hospitals and regulatory bodies to sustain the already established DIC and to establish additional DICs in the future to provide quality health care service to the community.

Cytoplasmic p16 Is Expressed in Normal Brown Fat and Hibernomas

White adipose tissue browning has emerged as a putative therapy of obesity, and studies in mice have shown that Cdkn2a is implicated in white-to-brown transition. However, the role of Cdkn2a product p16 has been never studied in human brown fat tissue. The aim of the study is to investigate the expression of p16 in normal brown fat and in hibernoma, a lipoma containing brown fat-like adipocytes. Ten normal brown fat tissues and 5 hibernomas were immunohistochemically studied for p16 expression. Nearby white adipose tissue was used for comparison. All brown fat and hibernomas specimens express p16 in a cytoplasmic manner. Neighboring white adipose tissue is negative for p16 expression. Thus, cytoplasmic p16 may be associated with fat tissue browning.