Mesenchymal tumours of the pleura: review and update.

Primary mesenchymal tumours of the pleura are uncommon and can be diagnostically challenging due to their overlapping histopathologic and immunophenotypic features. Herein we discuss selected mesenchymal tumours of the pleura, including solitary fibrous tumour, calcifying fibrous tumour, desmoid fibromatosis, synovial sarcoma, schwannoma, malignant peripheral nerve sheath tumour, inflammatory myofibroblastic tumour, follicular dendritic cell sarcoma, epithelioid hemangioendothelioma, and desmoplastic small round cell tumour. We review their clinicopathologic characteristics, along with an update on the relevant immunohistochemical and molecular features.

Inspiratory-expiratory variation of pleural line thickness in neonates with and without acute respiratory failure.

BACKGROUND: There are relatively few data about the ultrasound evaluation of pleural line in patients with respiratory failure. We measured the pleural line thickness during different phases of the respiratory cycle in neonates with and without acute respiratory failure as we hypothesized that this can significantly change. METHODS: Prospective, observational, cohort study performed in an academic tertiary neonatal intensive care unit recruiting neonates with transient tachypnoea of the neonate (TTN), respiratory distress syndrome (RDS) or neonatal acute respiratory distress syndrome (NARDS). Neonates with no lung disease (NLD) were also recruited as controls. Pleural line thickness was measured with high-frequency ultrasound at end-inspiration and end-expiration by two different raters. RESULTS: Pleural line thickness was slightly but significantly higher at end-expiration (0.53 [0.43-0.63] mm) than at end-inspiration (0.5 [0.4-0.6] mm; p = 0.001) for the whole population. End-inspiratory (NLD: 0.45 [0.38-0.53], TTN: 0.49 [0.43-0.59], RDS: 0.53 [0.41-0.62], NARDS: 0.6 [0.5-0.7] mm) and -expiratory (NLD: 0.47 [0.42-0.56], TTN: 0.48 [0.43-0.61], RDS: 0.53 [0.46-0.65], NARDS: 0.61 [0.54-0.72] mm) thickness were significantly different (overall p = 0.021 for both), between the groups although the absolute differences were small. The inter-rater agreement was optimal (ICC: 0.95 (0.94-0.96)). Coefficient of variation was 2.8% and 2.5% for end-inspiratory and end-expiratory measurements, respectively. These findings provide normative data of pleural line thickness for the most common forms of neonatal acute respiratory failure and are useful to design future studies to investigate possible clinical applications.

Peripheral blood eosinophils: an important reference for radiologists to distinguish between pulmonary paragonimiasis and tuberculous pleurisy in children.

OBJECTIVE: In this study, we examined the value of chest CT signs combined with peripheral blood eosinophil percentage in differentiating between pulmonary paragonimiasis and tuberculous pleurisy in children. METHODS: Patients with pulmonary paragonimiasis and tuberculous pleurisy were retrospectively enrolled from January 2019 to April 2023 at the Kunming Third People's Hospital and Lincang People's Hospital. There were 69 patients with pulmonary paragonimiasis (paragonimiasis group) and 89 patients with tuberculous pleurisy (tuberculosis group). Clinical symptoms, chest CT imaging findings, and laboratory test results were analyzed. Using binary logistic regression, an imaging model of CT signs and a combined model of CT signs and eosinophils were developed to calculate and compare the differential diagnostic performance of the two models. RESULTS: CT signs were used to establish the imaging model, and the receiver operating characteristic (ROC) curve was plotted. The area under the curve (AUC) was 0.856 (95% CI: 0.799-0.913), the sensitivity was 66.7%, and the specificity was 88.9%. The combined model was established using the CT signs and eosinophil percentage, and the ROC was plotted. The AUC curve was 0.950 (95% CI: 0.919-0.980), the sensitivity was 89.9%, and the specificity was 90.1%. The differential diagnostic efficiency of the combined model was higher than that of the imaging model, and the difference in AUC was statistically significant. CONCLUSION: The combined model has a higher differential diagnosis efficiency than the imaging model in the differentiation of pulmonary paragonimiasis and tuberculous pleurisy in children. The presence of a tunnel sign on chest CT, the absence of pulmonary nodules, and an elevated percentage of peripheral blood eosinophils are indicative of pulmonary paragonimiasis in children.

Cause specific mortality in an Italian pool of asbestos workers cohorts.

BACKGROUND: Asbestos is a known human carcinogen and is causally associated with malignant mesothelioma, lung, larynx and ovarian cancers. METHODS: Cancer risk was studied among a pool of formerly asbestos-exposed workers in Italy. Fifty-two Italian asbestos cohorts (asbestos-cement, rolling-stock, shipbuilding, and other) were pooled and their mortality follow-up was updated to 2018. Standardized mortality ratios (SMRs) were computed for major causes of death considering duration of exposure and time since first exposure (TSFE), using reference rates by region, age and calendar period. RESULTS: The study included 63,502 subjects (57,156 men and 6346 women): 40% who were alive, 58% who died (cause known for 92%), and 2% lost to follow-up. Mortality was increased for all causes (SMR: men = 1.04, 95% confidence interval [CI] 1.03-1.05; women = 1.15, 95% CI 1.11-1.18), all malignancies (SMR: men = 1.21, 95% CI 1.18-1.23; women = 1.29, 95% CI 1.22-1.37), pleural and peritoneal malignancies (men: SMR = 10.46, 95% CI 9.86-11.09 and 4.29, 95% CI 3.66-5.00; women: SMR = 27.13, 95% CI 23.29-31.42 and 7.51, 95% CI 5.52-9.98), lung (SMR: men = 1.28, 95% CI 1.24-1.32; women = 1.26, 95% CI 1.02-1.53), and ovarian cancer (SMR = 1.42, 95% CI 1.08-1.84). Pleural cancer mortality increased during the first 40 years of TSFE (latency), reaching a plateau thereafter. CONCLUSIONS: Analyses by time-dependent variables showed that the risk for pleural neoplasms increased with latency and no longer increases at long TSFE, consistent with with asbestos clearance from the lungs. Peritoneal neoplasm risk increased over all observation time.

Breast ultrasound: An opportunity to detect unsuspected pleural and pulmonary abnormalities.

PURPOSE: While scanning women for breast US, is possible to observe changes in the appearance of the pleural line or in the most superficial portion of the lung. The objective of this single-center, prospective study was to determine the prevalence of a variety of pleural and pulmonary US findings during routine breast US. METHODS: In this study, there were 200 women undergoing standard breast US examination. The presence of pleural and pulmonary abnormalities in these cases was recorded. Two off-site reviewers confirmed the presence of pleura and lung changes. RESULTS: There was no abnormal finding in 168 out of 200 cases (84%) while there were one or more abnormal findings in 32 cases (16%). Pleural effusion was observed in 0.5% of cases, thickening of the pleural line 5% of cases, irregularity of the pleural line in 6% of cases, increased number of vertical artifacts in 9% of cases, subpleural nodulations in 2% of cases, and lung consolidation in 0.5%. CONCLUSION: Pleural and lung changes are not uncommon during breast US. Operators performing breast US examinations should be aware of the possibility to identify unsuspected pleuro-pulmonary abnormalities.

Modern view on the problem of acute pleural empyema surgical treatment.

OBJECTIVE: Aim: data study on the results of treatment of acute non-specific purulent-destructive pleura diseases with the purpose of further improvement of its results on the basis of improvement of diagnostics, identification of factors of disease prognosis and by implementing differential tactics of surgical treatment with the use of minimally invasive interventions. PATIENTS AND METHODS: Materials and Methods: We have studied modern literary sources on the topic of current trends in the treatment of acute pleural empyema and its complications. The studied material is summarized and presented in the form of a literature review in this article. CONCLUSION: Conclusions: These issues cannot be considered to be completely solved and require further study. Everything mentioned above dictates the search of new effective methods of the treatment of the mentioned pathology and proves the relevance of the theme. The outlined information highlights the necessity of improvement of surgical tactics in patients with pleural empyema.

Comparison of midpoint transverse process to pleura (MTP) block and erector spinae plane block (ESP) for postoperative analgesia in modified radical mastectomy patients: A double-blinded, randomized control trial.

Background and Aims: Modified radical mastectomy (MRM) is associated with moderate severity of postoperative pain. Besides intravenous (IV) analgesics, various nerve blocks are being described for pain relief of MRM patients. We compared erector spinae plane (ESP) block with midpoint transverse process to pleura (MTP) block in these patients for postoperative analgesia. Material and Methods: After receiving ethical committee approval from the institutional ethics committee (AIIMS, Jodhpur) and written informed consent from study participants, 66 patients who were assigned American Society of Anesthesiologists (ASA) physical status I and II, aged 18-75 years, and were scheduled to undergo MRM were enrolled and randomly allocated into two groups. Unilateral block was given before surgery at T3 or T4 level and with 15 ml of 0.5% ropivacaine in both the groups. Infusion of 0.5% ropivacaine (Neon laboratories limited, Mumbai, India) and 0.2% ropivacaine at a rate of 5 ml/h was maintained intraoperatively and postoperatively, respectively. Pain was assessed using the Visual Analogue Scale (VAS) for the next 24 hours. The total number of patients needing rescue analgesia, the total amount of rescue analgesics consumed in the next 24 hours, and patient satisfaction score were also compared between groups. Results: Demographics and baseline vitals were comparable in the groups. On comparing VAS scores in both the groups during rest and movement at different time intervals, there was no difference in pain scores during the initial two hours. From the third hour, there was a statistically significant difference (P < 0.001) in pain VAS scores in both groups. The ESP group had lower VAS scores compared to the MTP group when followed for the next 24 hours. There was a statistically significant difference in patient satisfaction. Conclusion: ESP block is more efficacious when compared to MTP block for postoperative analgesia in MRM patients.

Diagnostic yields and safety of thoracoscopic cryobiopsies in Japan: A single-center retrospective observational study.

BACKGROUND: Thoracoscopy is useful for diagnosing unexplained pleural effusions. A sufficient specimen volume is often difficult to obtain using forceps biopsies (FBs) but can be obtained with pleural cryobiopsies (CBs). This study aimed to assess the utility and safety of CB during thoracoscopy in the Japanese population. METHODS: Patients who underwent thoracoscopic CBs at the Japanese Red Cross Medical Center between January 2017 and August 2023 were included in the study. Data were retrospectively analyzed, including clinical data, thoracoscopic findings, specimen size, diagnostic yield, and complications. The number of collected specimens and the freezing time were left to the discretion of the attending physician. RESULTS: Twenty-six patients underwent thoracoscopic CB. Specimens obtained by CB were larger than those obtained by FB. Primary lung cancer was the most common cause of pleural effusion, followed by malignant pleural mesothelioma. CB contributed to the diagnosis in 24 of 26 cases (92.3%) and FB contributed to the diagnosis in 11 of 18 cases (61.1%). Severe fibrosis could be diagnosed in all 3 cases by CB, but not by FB. The common complications of CB included bleeding at the biopsy site and atelectasis, but no severe complications occurred. CONCLUSIONS: The utility and safety of thoracoscopic CB for diagnosing pleural effusions in Japan were verified. The diagnostic yield, specimen size, and safety profile of CB support the diagnostic utility of this method.

The Pleural Origin of Retiform Hemangioendothelioma: An Unusual Origin of a Rare Diagnosis.

Introduction: Vascular malignancies are categorized into benign hemangiomas, malignant angiosarcomas, and tumors of intermediate malignancy. Retiform hemangioendothelioma (RH) is one of the rare diagnoses belonging to the class of intermediate malignancies that was initially diagnosed. Case Presentation: In this case report, we have reported a rare case of RH, a locally aggressive, vascular tumor of malignant potential presenting at an unusual site. The most observed locations of this soft tissue tumor are skin and subcutaneous tissues of extremities; however, this case of RH was observed in an unusual site called pleura, which is a rare occurrence related to this tumor. The presence of cell surface markers like CD31 and ERG of vascular and endothelial origin and the presence of hobnail appearance of endothelial channels on the biopsy profile supported the vascular origin of the tumor; the clinical features and imaging studies further confirmed the diagnosis of RH. Conclusion: In this case report, a rare case of RH with an unusual site of origin was highlighted. RH is a vascular neoplasm; commonly observed sites of this vascular tumor were skin and subcutaneous tissue of the extremities; however, in this case, the site was unusually different, which was the pleura of the left lung.

The Role of Medical Thoracoscopy with Talc Poudrage in Spontaneous, Iatrogenic, and Traumatic Pneumothorax: A Prolonged Experience of a Tertiary Care Center.

INTRODUCTION: Medical thoracoscopy is a minimally invasive and safe procedure mostly performed for unexplained exudative pleural effusions but may be considered for pneumothorax (PNX). METHODS: This retrospective study included participants affected by PNX who underwent medical thoracoscopy with talc poudrage at a single academic hospital from 2008 to 2021. The primary endpoint was the observation of complete radiographical lung re-expansion and absence of air supply from the chest drain within 7 days of medical thoracoscopy. The secondary endpoint was achieving no recurrence of ipsilateral PNX at 24 months post-discharge. RESULTS: A total of 95 patients affected by primary spontaneous PNX (PSP), secondary spontaneous PNX (SSP), iatrogenic, and traumatic PNX were enrolled. An additional procedure was required by 17.89% of patients, and only one patient with SSP required subsequent surgery. Recurrence of PNX occurred on the same side within 24 months after discharge in 9.47% of patients, with a median time to recurrence of 13.5 months. The PSP group was significantly more likely to achieve the primary endpoint. Pleural morphology was significantly associated with reaching the primary endpoint, while receiving a cumulative dose of talc greater than or equal to 4 g during hospitalization was associated with a lower risk of meeting it. Receiving a cumulative dose of talc greater than or equal to 4 g led in all cases to the achievement of the secondary endpoint. Patients with iatrogenic and traumatic PNX had an excellent prognosis in both the short- and long-term evaluation. CONCLUSION: Medical thoracoscopy is an effective procedure for treating PNX in the acute setting in selected cases while preventing long-term relapses. Large prospective clinical studies are needed to support and better define the role of medical thoracoscopy in current clinical practice.

Time-Sequential Monitoring of the Early Mesothelial Reaction in the Pleura after Cryoinjury.

(1) Background: An early mesothelial reaction of the pleura, leading to fibrosis, has been reported in animals after chemical or heavy metal exposure. However, the visual monitoring of early time-sequential mesothelial reaction-associated cryoinjury has not been fully investigated. Therefore, this study aimed to evaluate and visualize the early mesothelial reactions seen following cryoinjury using rabbit pleura. (2) Methods: We monitored the early mesothelial reaction in rabbit pleurae after cryoinjury using optical coherence tomography (OCT), in real-time, which was then compared with pathological images. Due to the penetration limit of OCT, we made a thoracic window to image the parietal and visceral pleurae in vivo. We also used an innovative technique for capturing the microstructure in vivo, employing a computer-controlled intermittent iso-pressure breath hold to reduce respiratory motion, increasing the resolution of OCT. We organized three sample groups: the normal group, the sham group with just a thoracic window, and the experimental group with a thoracic window and cryotherapy. In the experimental group, localized cryoinjury was performed. The mesothelial cells at the level of pleura of the cryotherapy-injured site were visualized by OCT within the first 30 min and then again after 2 days at the same site. (3) Results: In the experimental group, focal thickening of the parietal pleura was observed at the site of cryoinjury using OCT after the first injury, and it was then confirmed pathologically as focal mesothelial cell proliferation. Two days after cryoinjury, diffuse mesothelial cell proliferation in the parietal pleura was noted on the reverse side around the cryoinjured site in the same rabbit. In the sham group, no pleural reaction was found. The OCT and pathological examinations revealed different patterns of mesothelial cell reactions between the parietal and visceral pleurae: the focal proliferation of mesothelial cells was found in the parietal pleura, while only a morphological change from flat cells to cuboidal cells and a thickened monolayer without proliferation of mesothelial cells were found in the visceral pleural. (4) Conclusions: An early mesothelial reaction occurs following cryoinjury to the parietal and visceral pleurae.

Fluoroscopy-Guided Percutaneous Transthoracic Pleural Forceps Biopsy in Patients With Exudative Pleural Effusion.

OBJECTIVE: This study aimed to evaluate the diagnostic performance and procedural characteristics of fluoroscopy-guided percutaneous transthoracic pleural forceps biopsy (PTPFB) in patients with exudative pleural effusion. MATERIALS AND METHODS: Patients with exudative pleural effusion who underwent PTPFB between May 1, 2014, and February 28, 2023, were included in this retrospective study. The interval between percutaneous catheter drainage (PCD) and PTPFB, number of biopsies, procedural time, and procedure-related complications were evaluated. The sensitivity, specificity, and accuracy of diagnosing malignancy were computed for pleural cytology using PCD drainage, PTPFB, and combined PTPFB and pleural cytology. RESULTS: Seventy-one patients, comprising 50 male and 21 female (mean age, 69.5 ± 15.3 years), were included in this study. The final diagnoses were benign lesions in 48 patients (67.6%) and malignant in 23 patients (32.4%). The overall interval between PCD and biopsy was 2.4 ± 3.7 days. The interval between PCD and biopsy in the group that underwent delayed PTPFB was 5.2 ± 3.9 days. The mean number of biopsies was 4.5 ± 1.3. The mean procedural time was 4.4 ± 2.1 minutes. Minor bleeding complications were reported in one patient (1.4%). The sensitivity, specificity, and accuracy for pleural cytology, PTPFB, and combined PTPFB and pleural cytology were 47.8% (11/23), 100% (48/48), and 83.1% (59/71), respectively; 65.2% (15/23), 100% (48/48), and 88.7% (63/71), respectively; and 78.3% (18/23), 100% (48/48), and 93.0% (66/71), respectively. The sensitivity and accuracy of cytology combined with PTPFB were significantly higher than those of cytological testing alone (P = 0.008 and 0.001, respectively). CONCLUSION: Fluoroscopy-guided PTPFB is an accurate and safe diagnostic technique for patients with exudative pleural effusion, with acceptable diagnostic performance, low complication rates, and reasonable procedural times.

Pleural lung sliding quantification using a speckle tracking technology: A feasibility study on 30 healthy volunteers.

INTRODUCTION: Speckle tracking technology quantifies lung sliding and detects lung sliding abolition in case of pneumothorax on selected ultrasound loops through the analysis of acoustic markers. OBJECTIVES: We aimed to test the ability of speckle tracking technology to quantify lung sliding using a pleural strain value (PS). METHODS: We performed a prospective study in 30 healthy volunteers in whom we assessed the pleural speckle tracking using ultrasound loops. Seven breathing conditions with and without non-invasive ventilation were tested. Two observers analyzed the ultrasound loops in four lung areas (anterior and posterior, left and right) and compared the obtained PS values. The first endpoint was to determine the feasibility of the PS measurement in different breathing conditions. The secondary endpoints were to assess the intra- and inter-observer's reliability of the measurement to compare PS values between anterior and posterior lung areas and to explore their correlations with the measured tidal volume. RESULTS: We analyzed 1624 ultrasound loops from 29 patients after one volunteer's exclusion. Feasibility of this method was rated at 90.8 [95%CI: 89.6 - 92.4]%. The intra-observer reliability measured through Intraclass Correlation Coefficients was 0.96 [95%CI: 0.91-0.98] and 0.93 [95%CI: 0.86-0.97] depending on the operator. The inter-observer reliability was 0.89 [95%CI: 0.78-0.95]. The PS values were significantly lower in the anterior lung areas compared with the posterior areas in all breathing conditions. A weak positive correlation was found in all the lung areas when a positive end expiratory pressure was applied with r = 0.26 [95%CI: 0.12;0.39]; p < 0.01. CONCLUSION: Speckle tracking lung sliding quantification with PS was applicable in most conditions with an excellent intra- and inter-observer reliability. More studies in patients under invasive mechanical ventilation are needed to explore the correlation between PS values of pleural sliding and tidal volumes. CLINICAL REGISTRATION: NCT05415605.

Erratum: The Rat Thoracic Ultrasound protocol: scanning technique and normal findings.

[This corrects the article DOI: 10.3389/fvets.2024.1286614.].

The Rat Thoracic Ultrasound protocol: scanning technique and normal findings.

Respiratory diseases (especially pneumonia) are very common disorders in pet rats. The suspected diagnosis is mostly based on the clinical signs, thoracic auscultation, and thoracic radiography. However, auscultation is insensitive in determining the severity of the disease, and radiographs are often unremarkable. Non-cardiac thoracic ultrasonography is increasingly used in veterinary medicine; however, it has not been described in detail in rats. Thoracic ultrasonic examination was conducted on 400 client-owned conscious pet rats. The rats were examined in the period from June 2023 to August 2023 in two veterinary clinics. Due to the small size of the animal, different anatomical considerations, and different evaluation protocols, as well as to meet the optimal outcome of detailed thoracic ultrasound, a standard methodological protocol was developed, and the name RATTUS (Rat Thoracic Ultrasound) was proposed. Typical signs of normal RATTUS were described (bat sign, lung sliding, A-lines, abdominal curtain sign, ski jump sign, lung pulse, seashore sign in M-mode, and bamboo sign). The new evaluation of lung inflation symmetry by substernal access was also described. The methodical approach presented and the normal findings description are proposed to be used for a standard/routine thoracic ultrasound examination in pet rats.

Empyema in children.

Empyema is the infection of the fluid in the pleural space due to different causes. The most common cause of empyema in children is parapneumonic effusion. Although its frequency has decreased significantly with the use of antibiotics, it is still a significant cause of morbidity and mortality worldwide. The main aim in the treatment of empyema is to drain the pleural cavity to provide reexpansion of the compressed lung, to treat the parenchymal infection with appropriate antibiotic therapy, and to prevent complications that may develop in the acute and chronic periods. Treatment options for this disease vary depending on the stage of the disease. Treatment success in childhood empyema detected at an early stage is high. The diagnosis and treatment of empyema in children differs from adults. Due to rapid tissue regeneration in childhood, healing can occur without the need for aggressive treatment options.

BAP1 Loss, Nuclear Grading, and Nonepithelioid Features in the Diagnosis of Mesothelioma in Italy: Nevermore without the Pathology Report.

The pathologic diagnosis of pleural mesothelioma is generally based on international guidelines, but no compulsory points based on different drugs approvals in different European countries are required to be reported. According to the last (2021) edition of the World Health Organization classification of pleural tumors, the nuclear grade of epithelioid-type mesothelioma should be always inserted in the pathologic report, while the presence of BRCA-associated protein-1 (BAP1) (clone C4) loss and a statement on the presence of the sarcomatoid/nonepithelioid component are fundamental for both a screening of patients with suspected BAP1 tumor predisposition syndrome and the eligibility to perform first-line immunotherapy at least in some countries. Several Italian experts on pleural mesothelioma who are deeply involved in national scientific societies or dedicated working groups supported by patient associations agreed that the pathology report of mesothelioma of the pleura should always include the nuclear grade in the epithelioid histology, which is an overt statement on the presence of sarcomatoid components (at least 1%, in agreement with the last classification of pleural mesothelioma) and the presence of BAP1 loss (BAP1-deficient mesothelioma) or not (BAP1-retained mesothelioma) in order to screen patients possibly harboring BAP1 tumor predisposition syndrome. This review aims to summarize the most recent data on these three important elements to provide evidence regarding the possible precision needs for mesothelioma.

Solitary fibrous tumours of the pleura: do we need a different perspective on malignancy?

OBJECTIVES: Solitary fibrous tumours of the pleura (SFTP) are historically considered to be benign soft tissue neoplasms. However, a clinical relevant number of these neoplasms have malignant histological features. The objective of this study was to evaluate the percentage of SFTP presenting unfavourable clinical behaviour in order to predict negative long-term outcome. METHODS: A retrospective review of 74 patients treated at 4 hospitals between 1990 and 2013 was performed. The median follow-up was 10 years (range: 1-20 years). Risk of tumour recurrence and metastases (unfavourable clinical behaviour) with regard to histology using the Kaplan-Meier and Cox proportional hazards methods. RESULTS: The mean age was 61 years (SD 12.75 years). There were 31 male patients (58%) and 43 female patients (42%). Tumour size ranged from 1 to 30 cm (mean 9.09 cm; SD 6.22 cm). Complete resection (R0) was achieved by minimally invasive thoracoscopic resection in 29% and thoracotomy in 57%; 25% of SFTPs showed histological evidence of malignancy, according to England criteria. Recurrence occurred in 21% and 10% of patients had metastases; 83% of patients with metastases and 39% of patients with recurrence died within 5 years. The median recurrence-free survival for histologically benign SFTP was not reached, compared to 8 years for malignant SFTP. The five-year overall survival rate was 84%. Mitotic rate ≥1/10 HPF, high cellularity, nuclear atypia, Ki-67 level >5% and poorly circumscribed (sessile) growth pattern were associated with poor long-term outcome. CONCLUSIONS: Pathological differentiation of SFTP morphology into pedunculated, well circumscribed and poorly circumscribed (sessile) growth pattern is recommended. Due to the misleading classification into histologically benign and malignant, all unpedunculated SFTP should be classified as potentially aggressive. Lifelong follow-up is mandatory.

Nonmesothelial Spindle Cell Tumors of Pleura and Pericardium.

Spindle cell lesions of the pleura and pericardium are rare. Distinction from sarcomatoid mesothelioma, which has a range of morphologic patterns, can be difficult, but accurate diagnosis matters. This article provides practical guidance for the diagnosis of pleural spindle cell neoplasms, focusing on primary lesions.

Primary extraskeletal osteosarcomas of the pleura: A clinicopathological, immunohistochemical, and molecular analysis of 4 cases.

Four primary extraskeletal osteosarcomas of the pleura are presented. The patients were men between the ages of 63 and 78 years (average: 70.5 years) who presented with symptoms of chest pain, cough, and shortness of breath. Diagnostic imaging showed variably calcified, pleural-based masses and/or diffuse pleural thickening, clinically mimicking mesothelioma. Thoracoscopic surgical material was obtained for histopathological diagnosis. Histological findings showed the presence of a neoplastic spindle cell proliferation composed of fusiform cells with scant cytoplasm, elongated nuclei and inconspicuous nucleoli. Mitotic activity was easily identified. Additionally, all tumors showed extensive osseous differentiation in the form of osteoid matrix production; one tumor demonstrated additional chondrosarcomatous elements and another showed focal myxoid changes. Immunohistochemical analysis revealed that the tumor cells were uniformly negative for a wide variety of antibodies, including keratin AE1/AE3, keratin 5/6, D2-40, EMA, calretinin, WT-1, BerEP4, and HEG1; BAP1 was retained in all cases. In addition, fluorescence in situ hybridization for CDKN2A (p16) was negative for homozygous deletion in all tumors. Clinical follow-up showed that one patient had died 8 months after diagnosis and one had remained alive with short post-diagnostic follow-up. The tumors herein described highlight a challenging issue in the separation of mesothelioma with heterologous elements from true osteosarcomas of pleural origin. We propose that a diagnosis of extraskeletal osteosarcoma of the pleura is rendered for tumors with malignant osseous and/or cartilaginous differentiation in which comprehensive immunohistochemical studies and FISH analysis have failed to provide support for a diagnosis of mesothelioma with heterologous elements.