Pulmonary sclerosing pneumocytoma remains a diagnostic challenge using frozen sections: a clinicopathological analysis of 59 cases

Revisiting Pulmonary Sclerosing Pneumocytoma

Pulmonary sclerosing pneumocytoma (PSP) is a quite rare tumor outside Eastern countries. This rarity, together with a wide histological appearance, makes its correct identification a diagnostic challenge for pathologists under the microscope. Historically, PSP was considered a vascular-derived neoplasm (sclerosing hemangioma), but its immunohistochemical profile clearly supports its epithelial origin. No specific molecular fingerprint has been detected so far. This short narrative revisits the clinical, histological, immunohistochemical, and molecular aspects of this tumor, paying special attention to some controversial points still not well clarified, i.e., clinical aggressiveness and metastatic spread, multifocality, the supposed development of sarcomatoid change in a subset of cases, and tumor associations with lung adenocarcinoma and/or well-differentiated neuroendocrine hyperplasia/tumors. The specific diagnostic difficulties on fine-needle aspiration cytology/biopsy and perioperative frozen sections are also highlighted. Finally, a teaching case of tumor concurrence of lung adenocarcinoma, neuroendocrine lesions, and PSP, paradigmatic of tumor association in this context, is also presented.

CT-based radiomics for differentiating peripherally located pulmonary sclerosing pneumocytoma from carcinoid

BACKGROUND

Pulmonary sclerosing pneumocytoma (PSP) and pulmonary carcinoid (PC) are difficult to distinguish based on conventional imaging examinations. In recent years, radiomics has been used to discriminate benign from malignant pulmonary lesions. However, the value of radiomics based on computed tomography (CT) images to differentiate PSP from PC has not been well explored.

PURPOSE

We aimed to investigate the feasibility of radiomics in the differentiation between PSP and PC.

METHODS

Fifty-three PSP and fifty-five PC were retrospectively enrolled and then were randomly divided into the training and test sets. Univariate and multivariable logistic analyses were carried to select clinical predictor related to differential diagnosis of PSP and PC. A total of 1316 radiomics features were extracted from the unenhanced CT (UECT) and contrast-enhanced CT (CECT) images, respectively. The minimum redundancy maximum relevance and the least absolute shrinkage and selection operator were used to select the most significant radiomics features to construct radiomics models. The clinical predictor and radiomics features were integrated to develop combined models. Two senior radiologists independently categorized each patient into PSP or PC group based on traditional CT method. The performances of clinical, radiomics, and combined models in differentiating PSP from PC were investigated by the receiver operating characteristic (ROC) curve. The diagnostic performance was also compared between the combined models and radiologists.

RESULTS

In regard to differentiating PSP from PC, the area under the curves (AUCs) of the clinical, radiomics, and combined models were 0.87, 0.96, and 0.99 in the training set UECT, and were 0.87, 0.97, and 0.98 in the training set CECT, respectively. The AUCs of the clinical, radiomics, and combined models were 0.84, 0.92, and 0.97 in the test set UECT, and were 0.84, 0.93, and 0.98 in the test set CECT, respectively. In regard to the differentiation between PSP and PC, the combined model was comparable to the radiomics model, but outperformed the clinical model and the two radiologists, whether in the test set UECT or CECT.

CONCLUSIONS

Radiomics approaches show promise in distinguishing between PSP and PC. Moreover, the integration of clinical predictor (gender) has the potential to enhance the diagnostic performance even further.

Multiple pulmonary sclerosing pneumocytoma, based on a study of 36 cases worldwide

To analyze the clinical characteristics and to improve clinicians' understanding of multiple pulmonary sclerosing pneumocytoma (PSP) patients. A total of 36 PSP patients with multiple tumor characteristics were identified from the literature search. They were compared with 43 solitary PSP patients diagnosed and treated in our hospital in the past 5 years. Thus, the pathogenesis, clinical symptoms, diagnosis methods, treatment strategies, and prognosis of pulmonary sclerosing pneumocytoma (PSP) patients with multiple tumors were explored. Patients with multiple PSP are mostly distributed in Asia (88.89%) and are females (83.33%). PSP can be located in any one lobe (19.44%), or grow across ipsilateral lobes (44.44%), or even, bilateral lobes (36.11%). It can be accompanied by metastasis (9.09%) and is prone to misdiagnosis (27.78%). Compared with solitary PSP, the occurrence age of multiple PSP was younger (mean ± standard deviation [SD]: 40.36 ± 18.12: 51.28 ± 12.74 years), but there was no significant difference in sex, tumor size (mean ± SD: 43.54 ± 46.18: 30.56 ± 17.62 mm), or symptoms. Individualized surgical resection is required for treatment, including pneumonectomy (17.65%), lobectomy (23.53%), subpulmonary lobectomy (38.24%), or combined lobectomy (5.88%). Multiple PSP is relatively rare. Surgical resection within a limited time should be the main treatment for such patients. The prognosis of patients with multiple PSP is generally good, but inappropriate diagnosis and treatment plans may lead to poor prognosis.

What's new in benign lung tumours?

While lung cancer is one of the most common malignancies routinely encountered by pathologists, benign pulmonary neoplasms are quite rare. However, it is important for pathologists to be familiar with the typical diagnostic features of benign lung tumors to avoid confusing them with malignant morphological mimics. There have also been intriguing discoveries in the genetics of benign pulmonary neoplasms in the past decade. This review will cover several of the most common benign lung tumors, including the diagnostic categories of pulmonary adenomas, bronchial papillomas, and benign mesenchymal tumors, with discussion of the current classification, differential diagnosis, and current knowledge regarding genetic drivers.

Central and peripheral pulmonary sclerosing pneumocytomas: multi-phase CT study and comparison with Ki-67

BACKGROUND

This study aimed to evaluate the multi-phase CT findings of central and peripheral pulmonary sclerosing pneumocytomas (PSPs) and compared them with Ki-67 to reveal their neoplastic nature.

PATIENTS AND METHODS

Multi-phase CT and clinical data of 33 PSPs (15 central PSPs and 18 peripheral PSPs) were retrospectively analyzed and compared their multi-phase CT features and Ki-67 levels.

RESULTS

For quantitative indicators, central PSPs were larger than peripheral PSPs (10.39 ± 3.25 cm3 vs. 4.65 ± 2.61 cm3, P = 0.013), and tumor size was negatively correlated with acceleration index (r = -0.845, P < 0.001). The peak enhancement of central PSPs appeared in the delayed phase, with a longer time to peak enhancement (TTP, 100.81 ± 19.01 s), lower acceleration index (0.63 ± 0.17), progressive enhancement, and higher Ki-67 level. The peak enhancement of peripheral PSPs appeared in the venous phase, with the shorter TTP (62.67 ± 20.96 s, P < 0.001), higher acceleration index (0.99 ± 0.25, P < 0.001), enhancement washout, and lower Ki-67 level. For qualitative indicators, the overlying vessel sign (86.67% vs. 44.44%, P = 0.027), prominent pulmonary artery sign (73.33% vs. 27.78%, P = 0.015), and obstructive inflammation/atelectasis (26.67% vs. 0%, P = 0.033) were more common in central PSPs, while peripheral PSPs were more common with halo sign (38.89% vs. 6.67%, P = 0.046).

CONCLUSIONS

The location of PSP is a possible contributing factor to its diverse imaging-pathological findings. The tumor size, multi-phase enhancement, qualitative signs, and Ki-67 were different between central and peripheral PSPs. Combined tumor size, multi-phase findings, and Ki-67 level are helpful to reveal the nature of the borderline tumor.

Pulmonary sclerosing pneumocytoma and mortality risk

Background

Surgical resection is usually recommended for the treatment of pulmonary sclerosing pneumocytoma (PSP). However, no comparative study has demonstrated that surgical resection leads to improved outcomes. We aimed to compare all-cause mortality between patients with PSP who underwent surgery or did not and those without PSP.

Methods

Participants aged ≥18 years who had pathologically diagnosed PSP between 2001 to 2018, at 3 hospitals were included. Randomly selected (up to 1:5) age-, sex-, and smoking status-matched controls without PSP who were randomly selected from those who underwent health checkups including chest CT were included. Mortality was compared using Kaplan–Meier estimates and Cox proportional hazards regression models. Literature review of studies reporting PSP was also conducted.

Results

This study included 107 patients with PSP (surgery:non-surgery, 80:27) and 520 matched controls. There were no cases of lymph node or distant metastasis, recurrence, or mortality from PSP. No significant difference in all-cause mortality risk was observed between the PSP surgery, PSP non-surgery, and non-PSP groups (log rank test P = 0.78) (PSP surgery vs. non-PSP: adjusted hazards ratio [aHR], 1.80; 95% confidence interval [CI], 0.22–14.6; PSP non-surgery vs. non-PSP: aHR, 0.77; 95% CI, 0.15–3.86; PSP surgery vs. PSP non-surgery: aHR, 2.35; 95% CI, 0.20–28.2). In the literature review, we identified 3469 patients with PSP from 355 studies. Only 1.33% of these patients reported metastasis, recurrence, or death.

Conclusions

All-cause mortality did not differ between patients with PSP and those without, irrespective of undergoing surgery. Our study and the literature review suggest that PSP has less impact on increased mortality risk.

Clinical Characteristics of Malignant Pulmonary Sclerosing Pneumocytoma Based on a Study of 46 Cases Worldwide

Objective

To analyze the clinical characteristics of patients with malignant pulmonary sclerosing pneumocytoma (PSP) with metastasis, recurrence, and growth and to improve clinicians’ understanding of PSP in patients with malignant tumor characteristics.

Methods

A total of 46 PSP patients with malignant tumor characteristics were identified in the literature search and compared with 38 patients with benign PSP diagnosed and treated in our hospital in the past 5 years. We explored the pathogenesis, clinical symptoms, diagnostic methods, treatment strategies and prognosis of PSP patients with malignant tumor.

Results

The characteristics of young age (≤41 years old), larger tumor (≥36mm), lymph node metastasis and distribution in East Asians are indicative of PSP with malignant potential. Such patients should undergo segmental resection or lobectomy, combined with necessary lymph node dissection or biopsy. All patients with PSP should have an entire course of follow-up management, because they may have an adverse prognosis such as recurrence, growth, metastasis, and even death.

Conclusion

PSP has the potential for malignancy. Anatomical lobectomy or segmental resection combined with lymph node dissection should be performed in PSP with some specific characteristics. Inappropriate diagnosis and treatment may lead to poor prognosis in PSP patients.

Pulmonary sclerosing pneumocytoma-a case series

Pulmonary sclerosing pneumocytoma (PSP) is a rare and interesting pulmonary tumour that presents a diagnostic challenge to the surgeon due to its bland symptomatology, indolent course, non-specific radiological features and ambiguous histopathological findings, which could lead to errors in management and prognostication. Herein, we present a series of 4 patients with PSP who were managed in our institution over a period of 8 years and briefly discuss relevant literature.

Analysis of the value of enhanced CT combined with texture analysis in the differential diagnosis of pulmonary sclerosing pneumocytoma and atypical peripheral lung cancer: a feasibility study

BACKGROUND

As a rare benign lung tumour, pulmonary sclerosing pneumocytoma (PSP) is often misdiagnosed as atypical peripheral lung cancer (APLC) on routine imaging examinations. This study explored the value of enhanced CT combined with texture analysis to differentiate between PSP and APLC.

METHODS

Forty-eight patients with PSP and fifty patients with APLC were retrospectively enrolled. The CT image features of the two groups of lesions were analysed, and MaZda software was used to evaluate the texture of CT venous phase thin-layer images. Independent sample t-test, Mann-Whitney U tests or χ² tests were used to compare between groups. The intra-class correlation coefficient (ICC) was used to analyse the consistency of the selected texture parameters. Spearman correlation analysis was used to evaluate the differences in texture parameters between the two groups. Based on the statistically significant CT image features and CT texture parameters, the independent influencing factors between PSP and APLC were analysed by multivariate logistic regression. Extremely randomized trees (ERT) was used as the classifier to build models, and the models were evaluated by the five-fold cross-validation method.

RESULTS

Logistic regression analysis based on CT image features showed that calcification and arterial phase CT values were independent factors for distinguishing PSP from APLC. The results of logistic regression analysis based on CT texture parameters showed that WavEnHL_s-1 and Perc.01% were independent influencing factors to distinguish the two. Compared with the single-factor model (models A and B), the classification accuracy of the model based on image features combined with texture parameters was 0.84 ± 0.04, the AUC was 0.84 ± 0.03, and the sensitivity and specificity were 0.82 ± 0.13 and 0.87 ± 0.12, respectively.

CONCLUSION

Enhanced CT combined with texture analysis showed good diagnostic value for distinguishing PSP and APLC, which may contribute to clinical decision-making and prognosis evaluation.

Unusual lung tumors-from morphology to genetics

Most pathologists are well versed in the diagnosis of lung cancer, given the common nature of the disease. Occasionally more unusual neoplasms are encountered in lung biopsies and resections, which may be difficult to distinguish from "run of the mill" lung cancer cases based on overlapping morphologic and immunophenotypic features. The accurate diagnosis of these rare entities is quite challenging and requires careful morphological examination paired with judicious use of ancillary immunohistochemical and genetic studies. Herein, the clinicopathological and genetic features of five unusual lung tumors will be reviewed, including thoracic SMARCA4-deficient undifferentiated tumor, NUT carcinoma, sclerosing pneumocytoma, primary pulmonary myxoid sarcoma/angiomatoid fibrous histiocytoma, and bronchiolar adenoma/ ciliated muconodular papillary tumor. Since recognition of these entities by pathologists is of increasing importance to guide prognosis and therapy, emphasis will be placed on practical tips to reach these rare diagnoses with confidence.

Case Report and Literature Review: Pulmonary Sclerosing Pneumocytoma With Multiple Metastases Harboring AKT1 E17K Somatic Mutation and TP53 C176Y Germline Mutation

Pulmonary Sclerosing Pneumocytoma (PSP) is considered as a benign tumor, although a few cases have been reported to have multiple lesions, recurrence, and even regional lymph nodes (LNs) metastasis. Here, we report a case of PSP with atypical histologic features and malignant biological behavior, and explore its molecular genetic changes. The 23-year-old male showed a 6.5-cm pulmonary nodule in the right middle lobe (RML) and enlarged media stinal LNs. He underwent thoracoscopic RML lobectomy, systematic LNs dissection, and mediastinal lymphadenectomy. The metastases to the cervical LNs and liver were detected in a short period and then resected. Postoperative pathological examination confirmed the diagnosis of PSP in all the lesions, based on the histological characteristics and immune phenotypes. Furthermore, whole-exome sequencing identified both AKT1 E17K somatic mutation and TP53 C176Y germline mutation in this case. Thus, we presented an extremely rare case of atypical PSP with rapid recurrence and multiply metastases, which can easily be misdiagnosed as primary lung cancer. In addition, PSP-specific AKT1 E17K somatic E17K somatic mutation accompanied with TP53 C176Y germline mutation may contribute to the malignant clinical course of this tumor.

A case of pulmonary sclerosing pneumocytoma diagnosed preoperatively using transbronchial cryobiopsy

Background

The preoperative diagnosis of pulmonary sclerosing pneumocytoma (PSP) is complicated since PSP has several histological structural patterns in the same neoplasm; hence, it is sometimes pathologically misdiagnosed as adenocarcinoma or carcinoid. In recent years, with the prevalence of transbronchial cryobiopsy (TBLC), we are able to obtain larger specimens than previously. However, to date, there have been no reports describing PSP diagnosed using TBLC.

Case reports

A 43-year-old man was referred to our hospital for an abnormal lesion in the left lung discovered on routine health examination. A computed tomography scan of the chest revealed a 14-mm heterogeneous round nodule with surrounding ground-glass opacity in the left lower lobe. The tumor size increased to 18 mm in three weeks, and he developed bloody sputum. TBLC was performed using radial endobronchial ultrasonography and fluoroscopy. An occlusion balloon and prophylactic epinephrine were used to prevent severe bleeding. Histologically, epithelioid cells with solid proliferation, various papillary lesions, and hemosiderin-laden histiocytes were observed. Immunohistochemical staining revealed the histiocytes positive for thyroid transcription factor-1 and vimentin, and the type II pneumocyte-like-cells positive for cytokeratin 7. The tumor was preoperatively diagnosed as a PSP; the patient underwent left basal segmentectomy and consequently, a final diagnosed of PSP was formulated.

Conclusion

We report the first case of PSP preoperatively diagnosed using TBLC. Therefore, cryobiopsy could be beneficial in the preoperative diagnosis of PSP.

Pulmonary Sclerosing Pneumocytoma: A Pre and Intraoperative Diagnostic Challenge. Report of Two Cases and Review of the Literature

Pulmonary sclerosing pneumocytoma is a rare benign pulmonary tumor of primitive epithelial origin. Because of the unspecific radiological features mimicking malignancies and its histological heterogeneity, the differential diagnosis with adenocarcinoma and carcinoid tumors is still challenging. We report our experience of two cases of sclerosing pneumocytoma, as well as a review of the literature. Immunohistochemical findings showed intense staining of the cuboidal epithelial cells for cytokeratin-pool and TTF-1, with focal positivity for progesterone receptors. Round and spindle cells expressed positivity for vimentin, TTF-1 and focally for the progesterone receptor. Cytologic diagnosis of pulmonary pneumocytoma requires the identification of its dual cell population, made up of abundant stromal cells and fewer surface cells. Since the pre- and intraoperative diagnosis should guide surgical decision making, obtaining a sufficient specimen size to find representative material in the cell block is of paramount importance.

Challenging of frozen diagnoses of small sclerosing pneumocytoma

Aims

An increasing number of small pulmonary nodules are being screened by CT, and an intraoperative diagnosis is necessary for preventing excessive treatment. However, there is limited literature on the frozen diagnosis of small sclerosing pneumocytomas (SPs). In particular, tumours smaller than 1 cm are challenging for pathologists performing intraoperative frozen diagnosis.

Methods

In total, 230 cases of SP were surgically resected between January 2015 and March 2019 at Shanghai Chest Hospital, and of them, 76 cases were smaller than 1 cm. The histology and clinical information of these 76 cases (33.0%, 76/230) were reviewed retrospectively, 54 cases of which were diagnosed intraoperatively, and the pitfalls were summarised. All diagnoses were confirmed on permanent sections and immunohistochemical sections.

Results

Histologically, 78.9% (60/76) of the small SP was dominated by one growth pattern, and solid and papillary growth pattern were the most commonly misdiagnosed circumstances. The rate of intraoperative misdiagnosis of these SP smaller than 1 cm was 11.1% (6/54).

Conclusions

The main reason for misdiagnosis was failure to recognise the dual cell populations and the cellular atypia. Diagnostic clues include the gross morphology, the presence of dual-cell populations and a hypercellular papillary core, foam cell accumulation in glandular spaces and haemorrhage and haemosiderin on the periphery. In spite of awareness of pitfalls some cases may still be essentially impossible to diagnose on frozen section.

Correlation Between Pulmonary Sclerosing Pneumocytoma Features and MSCT Imaging Manifestations in 34 Patients: Implications for Precision Medicine

Objective: To identify and analyze the multi-slice computed tomography (MSCT) imaging manifestations and clinicopathological features of PSP to improve the preoperative and intraoperative diagnosis of the disease. Method: This was a retrospective study conducted on the imaging and clinicopathological data of the PSP patients treated in two major hospitals in China from October 2001 to December 2019. The locations of lung lesions, clinical symptoms, surgical complications, MSCT imaging features, and the corresponding relationship with clinicopathological features were assessed. Then, a new diagnostic approach was defined and used to train imaging and pathological doctors (experimental group). Then, the diagnostic accuracy of the experimental group was evaluated in preoperative and intraoperative diagnosis of PSP. Results: Thirty-four PSP cases were analyzed (mean: 51.42; range: 39-69 years old). The peripheral type was more common, while 92% of the lesions located in the middle lobe of the right lung and the lower lobe of bilateral lungs. The shortest lesion edge-pleura distance ranged 0 to 30 mm and 46% of the lesions (16/34) were attached to the pleura, 62% (21/34) located at 0-5 mm, 92% (31/34) within 20 mm from the pleura. Diameters of the lesions ranged 8.58 to 68.41 mm, while most of them were 20-40 mm. All lesions showed enhancement, and 97% (33/34) were unevenly enhanced. PSP volume was negatively correlated with the total degree of enhancement (r = -0.587, p < 0.01), and the volume difference between the obvious enhancement zone and the slight enhancement zone (r = -0.795, p < 0.01). Welt vessel sign was observed in 61.7% (21/34) of cases, and none of welt vessels entered into the lesions. Vascular-like enhancement area inside the lesion showed no significant correlation with the welt vessels outside the lesion, and no case showed entrance of bronchus into the lesion. The trained experimental group showed significantly greater diagnostic accuracy than the control group. In particular, the accuracy rate of intraoperative frozen section diagnosis was 60% higher in the experimental group than the control group. Conclusion: PSP has characteristic imaging manifestations, which can be utilized to improve the preoperative and intraoperative diagnostic coincidence rate of PSP.

Molecular Genetic Landscape of Sclerosing Pneumocytomas

OBJECTIVES

Sclerosing pneumocytomas are rare pulmonary neoplasms that are typically benign. However, rare patients experience progressive disease, and therapy targeting specific genetic underpinnings could be an attractive therapeutic option. Recent studies have found recurrent AKT 1 mutations in sclerosing pneumocytoma, but little is known about whether oncogenic fusion genes may also be present.

METHODS

To better understand the genetic background, 10 sclerosing pneumocytomas were subjected to next-generation sequencing cancer mutation panel testing (n = 9) and/or RNA sequencing (n = 3). The patients were all women (average age, 47 years; range, 17-74 years).

RESULTS

Eight patients had solitary sclerosing pneumocytomas, while one had two tumors, and one had many bilateral tumors. Recurrent mutations were noted in genes involved in the mTOR pathway, including AKT1, PIK3R1, and PTEN. AKT1 alterations were particularly common, present in 78%. No recurrent genetic fusions were identified. The patient in our study with multiple bilateral lesions was treated with the mammalian target of rapamycin (mTOR) inhibitor everolimus, with no objective radiographic evidence of treatment response after 4 months.

CONCLUSIONS

Our data further support that abnormal activation of the mTOR pathway is a consistent genetic event in sclerosing pneumocytoma. This warrants further exploration to determine if mTOR pathway inhibitors may be effective in patients with metastatic or recurrent disease.

[Analysis of Clinical Characteristics of 35 Cases of Pulmonary Sclerosing Pneumocytoma]

BACKGROUND

Pulmonary sclerosing pneumocytoma (PSP) is rare benign lung tumor which usually develops in middle-aged women without typical clinical and imaging findings. PSP consists of two basic cell types (surface cubic epithelial cells and round mesenchymal cells) and four histological types (hemorrhagic, sclerotic, solid and papillary). It grows slowly, but it can metastasize to distant organs. The pathology before surgery is easily misdiagnosed. This study aims to improve clinicians' understanding of PSP by discussing the clinical characteristics of the disease.

METHODS

This represents a retrospective study of thirty-five patients diagnosed with pulmonary sclerosing pneumocytoma by pathological examination from January 2011 to December 2019.

RESULTS

A total of 35 patients in this study, 12 cases were male and 23 cases were female, the average age is 51 years old. 7 cases were discovered accidentally by physical examination or routine chest computed tomography (CT), and 28 cases were found due to symptoms such as cough, sputum, hemoptysis and chest pain. The imaging changes is mainly featured with isolated or clear circular or round-like single nodule and lump in the lungs. In this group, 12 cases underwent percutaneous lung biopsy, only 7 cases were diagnosed with PSP. A total of 28 patients underwent surgery, 24 cases underwent rapid frozen pathological biopsy, only 5 cases diagnosed with PSP. Postoperative pathological examination results shows that 1 case was diagnosed with keratotic squamous cell carcinoma with partial PSP, and the rest were diagnosed with PSP. The surgical and non-surgical patients were followed up for 1 to 8 years after discharge, and the overall recovery was good. The patients were no recurrence and metastasis on chest CT review.

CONCLUSIONS

PSP is a clinically rare benign lung tumor, which is more common in middle-aged women. The clinical manifestations and imaging features are lack of significance. Percutaneous lung puncture pathological examination and intraoperative rapid frozen pathological sections often leads to misdiagnosis. Final diagnosis relies on postoperative pathological work-up for most cases.

Expression of ALDH and SOX-2 in Pulmonary Sclerosing Pnemocytoma (PSP) of the Lung: Is There a Meaning Behind?

Background: Pulmonary sclerosing pneumocytoma (PSP) is a rare benign pulmonary tumor that derives from primitive respiratory epithelium of the pulmonary alveolus. The etiology and pathogenesis are still unclear. Histopathological diagnosis focuses on cells that are positive for TTF1, EMA, cytokeratin-7, and CAM 5.2. The aim of our study is to highlight the elevated expression of ALDH and the presence of SOX-2 in pulmonary sclerosing pneumocytoma.

Methods: We report five cases of pulmonary sclerosing pneumocytoma undergone surgery at our Division of Thoracic Surgery, during a period between 1994 and 2011. ALDH and SOX-2 markers were also tested for positivity in all the patients.

Results: Patients showed elevated expression of ALDH during immunohistochemistry and mild expression of SOX-2, although in two cases in which SOX-2 was highly expressed. Among these two patients, one presented with lymph node recurrence while the other had no recurrence with a PET-positive nodule. In particular, the patient who had developed recurrence had an ALDH score of 4 and a SOX-2 score of 3, whereas the patient with the PET-positive nodule showed an ALDH score of 4 with a mild SOX-2 expression of score 1.

Conclusions: This is the first attempt demonstrating the elevated expression of ALDH in this disease. SOX-2 expression was noted in both the patient who developed recurrence and the patient with a PET-positive nodule. We believe that further investigation may be highly useful to better characterize these two markers as well as understand their function.

Pulmonary sclerosing pneumocytoma with mediastinal lymph node metastasis: a case report

Pulmonary sclerosing pneumocytoma (PSP) is a rare tumor and the imaging appearance is usually a well-circumscribed nodule. Herein we present the clinicopathological features of a 25-year-old female patient with a 4 cm mass in the left upper lobe. She had undergone lobectomy with lymph node dissection with an incorrect intraoperative frozen section diagnosis of adenocarcinoma and diagnosed as a PSP with lymph node metastasis on permanent sections. The 3-year follow-up of the patient is uneventful.

Pulmonary sclerosing pneumocytoma in an 18-year-old male patient: A case report and literature review

RATIONALE

Pulmonary sclerosing pneumocytoma (PSP) is a rare benign tumor of the lung, mostly presented in Asian middle-aged women. Initially, it was considered as a vascular origin tumor, but then research evidence showed that it was derived from natural epithelial tissue. On imaging, this tumor may be found as a solitary well-circumscribed lung parenchymal lesion, and is often located in juxtapleural or juxtafissural positions. On histopathology, it consists of cuboidal surface cells and stromal round cells, both of which are positive for thyroid transcription factor-1. Here we report a case of a young PSP male patient and review the relevant literature in order to improve our understanding of this disease.

PATIENT CONCERNS

An 18-year-old man was referred to our hospital after accidentally finding a lesion on chest X-ray. Contrast-enhanced computed tomography showed a soft tissue mass with homogeneous enhancement in the left lower lobe posterior segment.

DIAGNOSES

The diagnosis of PSPs was confirmed by histopathological examination.

INTERVENTIONS AND OUTCOMES

The patient underwent a thoracoscopic wedge resection and was followed-up after that. One month later, he had good performance status with no recurrent tumors.

LESSONS

PSP in a young man is really uncommon, and is confused with malignant tumors. A histopathological examination is considered as the diagnostic gold standard for this uncommon tumor. Surgery is the main treatment.

Does additional resection of a positive microscopic ductal margin benefit patients with perihilar cholangiocarcinoma: A systematic review and meta-analysis

Background

The incidence of a positive microscopic ductal margin (R1) after surgical resection for perihilar cholangiocarcinoma (pCCA) remains high, but the beneficial of additional resection has not been confirmed by any meta-analysis and randomized clinical trials (RCT), which also increased the risk of morbidity and mortality. Hence, a systematic review is warranted to evaluate the clinical value of additional resection of intraoperative R1 for pCCA.

Methods

Eligible studies were searched by PubMed, MedLine, Embase, the Cochrane Library, Web of Science, from Jan.1^st 2000 to Nov.30^th 2019, evaluating the 1-, 3-, and 5-year overall survival (OS) rates of additional resection of intraoperative pathologic R1 for pCCA. Odds ratio (OR) with 95% confidence interval (CI) was used to determine the effect size by a randomized-effect model.

Results

Eight studies were enrolled in this meta-analysis, including 179 patients in the secondary R0 group, 843 patients in the primary R0 group and 253 patients in the R1 group. The pooled OR for the 1-, 3-, and 5-year OS rate between secondary R0 group and primary R0 group were 1.03(95%CI 0.64~1.67, P = 0.90), 0.92(95%CI 0.52~1.64, P = 0.78), and 0.83(95%CI 0.37~1.84, P = 0.65), respectively. The pooled OR for the 1-, 3-, and 5-year OS rate between secondary R0 group and R1 group were 2.14(95%CI 1.31~3.50, P = 0.002), 2.58(95%CI 1.28~5.21, P = 0.008), and 3.54(95%CI 1.67~7.50, P = 0.001), respectively. However, subgroup analysis of the West showed that the pooled OR for the 1-, and 3-year OS rate between secondary R0 group and R1 group were 2.05(95%CI 0.95~4.41, P = 0.07), 1.91(95%CI 0.96~3.81, P = 0.07), respectively.

Conclusion

With the current data, additional resection should be recommended in selected patients with intraoperative R1, but the conclusion is needed further validation.

AKT1 internal tandem duplications and point mutations are the genetic hallmarks of sclerosing pneumocytoma

Sclerosing pneumocytoma is a unique benign neoplasm of the lungs. The molecular alterations in sclerosing pneumocytoma are not well understood. In a previous whole-exome sequencing study, recurrent AKT1 point mutation was observed in about half of the cases of sclerosing pneumocytoma. However, in the remaining half, cancer-related mutations have still not been identified. In this study, we first analyzed the raw sequence data from the previous whole-exome sequencing study (PRJNA297066 cohort). Using Genomon-ITDetector, a special software for detection of internal tandem duplications, we identified recurrent internal tandem duplications in the AKT1 gene in 22 of the 44 tumor samples (50%). All the cases positive for AKT1 internal tandem duplications lacked AKT1 point mutations. Next, we performed targeted next-generation sequencing in an independent cohort of sclerosing pneumocytoma from our hospital (VGH-TPE cohort), and again identified recurrent AKT1 internal tandem duplications in 20 of the 40 (50%) tumor samples analyzed. The internal tandem duplications resulted in duplications of 7 to 16 amino acids in a narrow region of the Pleckstrin homology domain of the AKT1 protein. This region contains the interaction interface between the Pleckstrin homology and kinase domains, which is known to play a critical role in the activation of the AKT1 protein. Moreover, we found that AKT1 internal tandem duplications were mutually exclusive of other forms of AKT1 mutations, including point mutations and short indels. Taking all forms of AKT1 mutations together, we detected AKT1 mutations in almost all the sclerosing pneumocytomas in our study (PRJNA297066 cohort: 41 out of 44 cases, 93%; VGH-TPE cohort: 40 out of 40 cases, 100%). Our results suggest that AKT1 mutation is the genetic hallmark of sclerosing pneumocytoma. These results would help in better understanding of the pathogenesis of sclerosing pneumocytoma.

Concomitance of pulmonary spindle cell carcinoma and sclerosing pneumocytoma in a woman: A case report

RATIONALE

Pulmonary spindle cell carcinoma (PSCC) is a rare subset of pulmonary sarcomatoid carcinoma. PSCC is aggressive and has a poor prognosis. Pulmonary sclerosing pneumocytoma (PSP) is an asymptomatic slow-growing benign tumor, which usually occurs in middle-aged women.

PATIENT CONCERNS

Herein, we report a case of solitary PSCC, occurring concomitantly with PSP in a 74-year-old woman. The patient visited our institution with productive purulent cough, dyspnea after activity, and hemoptysis. Enhanced computed tomography revealed an inhomogeneous enhanced mass with central low-attenuation in the right upper lobe (RUL). The mass located in the right lower lobe (RLL) exhibited homogeneous enhancement.

DIAGNOSIS

These lesions were subsequently diagnosed as PSCC in the RUL and PSP in the RLL, following postoperative pathological examination.

INTERVENTIONS

We performed lobectomy for the RUL and wedge resection for the RLL in one procedure.

OUTCOMES

The patient did not experience complications after surgery. No radiological evidence of recurrence was observed on follow-up computed tomography performed within 7 months after the procedure.

LESSONS

This case fully reflects the importance of the differential preoperative diagnosis of benign and malignant solitary pulmonary nodules. However, a rare and aggressive malignant tumor may have imaging features typical of a lung abscess, which should be treated carefully.

First report of pulmonary sclerosing pneomucytoma with malignant transformation in both cuboidal surface cells and stromal round cells: a case report

BACKGROUND

Pulmonary sclerosing pneumocytoma (PSP) is a rare benign tumor. Although lymph node metastasis has been reported, it is still considered benign. No malignant transformation has been reported. This is the first case of malignant transformation of both cuboidal surface cells and stromal round cells.

CASE PRESENTATION

A 64-year-old male had been complaining of intermittent hemoptysis several times per day for eight months. Chest computed tomography scan showed parenchymal infiltration with cystic lesion in the right lower lobe accompanied by enlarged right hilar lymph nodes. Lobectomy and systemic lymph node dissection was performed. On grossly pathological examination, the lesion was 50 mm from the bronchial stump. It was a mixture of both cystic and solid components and 30 mm * 20 mm in size with unclear border. Microscopically, the cuboidal surface cells transformed to adenocarcinoma. The stromal round cells also had a malignant transformation. The Ki-67 proliferation index in malignant cuboidal surface cells and stromal round cells were 70 and 55%, respectively. Furthermore, E-cadherin was negative in primary tumor but positive in metastatic lymph node, which suggested that the mesenchymal to epithelial transition may play an important role in lymph node metastasis.

CONCLUSIONS

To our knowledge, we present the first case of malignant transformation of both cuboidal surface cells and stromal round cells in PSP. The process of mesenchymal to epithelial transition may play an important role in lymph node metastasis.