Pleuropulmonary Meningothelial Proliferations

Primary pulmonary meningioma: a case report

An asymptomatic 68-year-old woman, with a history of breast cancer 19 years ago, was unexpectedly found to have primary pulmonary meningioma during medical evaluation. This discovery is exceedingly rare, with only about 70 cases reported worldwide. Following uncomplicated surgical removal of the mass, the patient was discharged in good health on the third day after the procedure. Notably, initial analysis of a frozen tissue sample indicated hamartoma, but subsequent immune-histochemical pathological examination confirmed the presence of meningioma. Given the uncommon nature of this tumor, it is essential to report such cases to raise awareness about pulmonary meningioma as a potential cause of solitary lung nodules. This awareness can help prevent unnecessary chemotherapy or surgical interventions.

Pulmonary primary meningioma: A report of two cases and review of the literature

Introduction

Primary pulmonary meningioma (PPM) is rare, mostly asymptomatic, and difficult to recognize preoperatively. In this report, we describe two new cases of PPM and provide an updated review of the literature to enhance our understanding of PPM.

Case presentation

The first patient was a 53-year-old woman with an asymptomatic solitary pulmonary nodule in the right lower lobe on chest computed tomography (CT). Wedge resection of the right lung was performed and histological features of benign PPM were pathologically confirmed, which was further supported by immunohistochemistry. The second patient was a 63-year-old man who had a left pulmonary nodule during routine physical examination. CT revealed a solid nodule in the outer basal segment of the left lower lobe. The patient underwent a wedge resection of the left lower lobe and mediastinal lymph node dissection. Postoperative pathology confirmed the presence of two tumors: one adenocarcinoma and one PPM. Both cases were confirmed to be benign PPM (grade I) by pathological examination, with histological subtypes of fibrous and psammomatous.

Conclusions

Radiological imaging is crucial for the early detection of PPM, while pathological examination is necessary to confirm the diagnosis. Surgical treatment is recommended, and intraoperative frozen sections are essential for determining the extent of the operation.

Diffuse Pulmonary Meningotheliomatosis: Clinic-Pathologic Entity or Indolent Metastasis from Meningioma (or Both)?

Pulmonary minute meningothelial-like nodules (MMNs) are common incidental findings in surgical specimens, consisting of tiny proliferation (usually no larger than 5-6 mm) of bland-looking meningothelial cells showing a perivenular and interstitial distribution, sharing morphologic, ultrastructural, and immunohistochemical profiles with meningiomas. The identification of multiple bilateral MMNs leading to an interstitial lung disease characterized by diffuse and micronodular/miliariform patterns radiologically allows the diagnosis of diffuse pulmonary meningotheliomatosis (DPM). Nevertheless, the lung is the most common site of metastatic primary intracranial meningioma, and differential diagnosis with DPM may be impossible without clinic-radiologic integration. Herein, we report four cases (three females; mean age, 57.5 years) fitting the criteria of DPM, all incidentally discovered and histologically evidenced on transbronchial biopsy (2) and surgical resection (2). All cases showed immunohistochemical expression of epithelial membrane antigen (EMA), progesterone receptor, and CD56. Notably, three of these patients had a proven or radiologically suspected intracranial meningioma; in two cases, it was discovered before, and in one case, after the diagnosis of DPM. An extensive literature review (44 patients with DPM) revealed similar cases with imaging studies excluding intracranial meningioma in only 9% (4 of 44 cases studied). The diagnosis of DPM requires close correlation with the clinic-radiologic data since a subset of cases coexist with or follow a previously diagnosed intracranial meningioma and, thus, may represent incidental and indolent metastatic deposits of meningioma.

Diffuse pulmonary meningotheliomatosis with pan-TRK expression by immunohistochemistry: a novel finding and potential pitfall

BACKGROUND

Pulmonary meningothelial-like nodules (PMNs) are benign proliferations of unclear clinical significance. They are mainly asymptomatic lesions that are usually discovered during the pathologic evaluation of resected pulmonary specimens or following post-mortem examination. Diffuse pulmonary meningotheliomatosis (DPM), which presents as bilateral multiple PMNs throughout the lungs, has been described less frequently. DPMs are benign lesions associated with both neoplastic and non-neoplastic pulmonary conditions.

CASE PRESENTATION

We report the case of a 59-year-old female patient who presented with a history of cough. Computerized tomography (CT) imaging revealed multiple subcentimeter bilateral pulmonary nodules. transbronchial biopsies were obtained which revealed foci of nodular interstitial proliferations composed of epithelioid to spindled cells in a vague whorled pattern. Immunohistochemical stains were diffusely positive for EMA and progesterone receptor. Furthermore, pan-TRK exhibited strong and diffuse membranous expression in the lesional cells. INSM1 was negative for expression. RNA-based next-generation sequencing for the detection of NTRK fusions was performed and was negative for gene rearrangements involving NTRK1, NTRK2, and NTRK3.

CONCLUSION

Here, we report a rare case of DPM and report pan-TRK expression in PMNs which has not been described. We provide a brief review of the literature and provide insight into the potential physiologic nature of PMNs. Lastly, we emphasize the recognition of pan-TRK immunoexpression in PMNs to avoid potential diagnostic errors.

A Rare Case of Diffuse Bilateral Minute Pulmonary Meningothelial-like Nodules Increasing Over the Short Term and Resembling Metastatic Lung Cancer

A 54-year-old woman was referred to our hospital because computed tomography (CT) revealed multiple lung nodules during a health checkup. The nodules were up to 5 mm in diameter and randomly distributed in both lungs, appearing ring-shaped. No clinical symptoms were present. However, the nodes proliferated, and multiple lung metastases could not be ruled out, so a biopsy was performed to establish a diagnosis. She was diagnosed with minute pulmonary meningothelial-like nodules (MPMNs), and her condition had not deteriorated at the latest follow-up. Although rare, MPMNs can proliferate for a short time, but a biopsy to exclude malignant causes is essential.

Clinical, pathological and radiologic features of minute pulmonary meningothelial-like nodules

OBJECTIVES

Reports about the radiologic features of minute pulmonary meningothelial-like nodules are sparse. This study aims to investigate the radiologic features of minute pulmonary meningothelial-like nodules.

METHOD

From January 2016 to April 2019, 7589 patients underwent pulmonary resections at Fudan University Shanghai Cancer Center. Postoperative pathology records were reviewed retrospectively. Fifty-nine patients with minute pulmonary meningothelial-like nodule were included. The identification of minute pulmonary meningothelial-like nodules in pathology specimen included pathologically confirmed in resected nodules, and discovery in the peripheral tissue of other resected nodules incidentally. We went back and checked all the pre-operative scans of patients to analyze surgical decision and observe any change of visible minute pulmonary meningothelial-like nodule over time. Clinic, radiologic and pathological features were collected.

RESULT

Fifty-nine patients included 10 men and 49 women, with a mean age of 57.7. Five patients had history, while 54 patients were non-smokers. 79 min pulmonary meningothelial-like nodules was found. Of them, 36 nodules were not visible on computed tomography scan. 43 nodules were visible on computed tomography scan, with an average size of 5.3 mm in 29 patients. Computed tomography appearance included pure ground-glass opacity in 36, mixed in 2, and solid nodules in 5. Nearly half of patients had a pre-operative follow-up more than 6 months (13/29, 44.8%). The median pre-operative radiologic follow-up was 4.9 months. Approximately 90% of patients underwent pulmonary surgery because of other malignant nodule on chest computed tomography scan (52/59, 88.1%).

CONCLUSION

Most minute pulmonary meningothelial-like nodules tend to present as ground-glass opacity, especially pure ground-glass opacity. Continuous computed tomography monitoring revealed no radiologic change over time. Continuous computed tomography monitoring was necessary part of management of minute pulmonary meningothelial-like nodule.

Diffuse pulmonary meningotheliomatosis

We report the case of an 80-year-old woman presenting with randomly distributed ground glass nodules in the lungs. Since this imaging appearance can be confusing and can mimic other disease processes, it is important to have an organized approach. In this specific case, the distribution and appearance of nodules, their presence for a prolonged period as well as the clinical context were clues to the diagnosis of diffuse pulmonary meningotheliomatosis (DPM). The final diagnosis was established by surgical biopsy. This article reviews the current literature on DPM, imaging appearance, and an algorithmic approach to the presented case.

Primary pulmonary meningiomas: report of two cases and review of the literature

BACKGROUND

Meningiomas rarely occur outside the skull, and primary pulmonary meningiomas (PPMs) are more rare. Only a few cases have been reported in the literature. The clinicopathological characteristics are not clear and it is easy to be misdiagnosed, so it is very important to master its diagnosis and differential diagnosis.

METHODS

We report two women with primary pulmonary meningioma. At the time of physical examination, the small solitary pulmonary nodules were detected on chest radiograph, and wedge resection was performed by Video-assisted Thoracoscope Surgery(VATS), and histologic evaluation showed that the lesions were benign PPMs. The clinicopathological features, immunophenotype and differential diagnosis of PPMs were analyzed, with a review of the cases published in the literature.

RESULTS

The study group comprised of 40 patients, 14 males and 26 females. The median age was 56.5 years (range 18-108). Thirty patients who underwent routine screening studies were asymptomatic but had a pulmonary nodule detected on chest X-ray. Nine patients had respiratory symptoms. Only 1 patient had non-specific symptoms. Most of the PPMs were benign, only 3 cases were malignant. Benign PPMs ranged from 0.6 cm to 6 cm in diameter (median 2 cm). The 3 malignant PPMs were 5 cm, 6.5 cm and 15 cm in diameter. The prognosis of benign PPM resection is good, with almost no recurrence or metastasis. But the two of three malignant PPMs relapsed.

CONCLUSIONS

PPM is very rare. It needs to be diagnosed by combining histology and immunohistochemistry. Diseases that need to be identified include spindle cell mesothelioma, spindle cell thymoma, spindle cell carcinoma, metastatic tumor, etc.

Radiological manifestations, histological features and surgical outcomes of pulmonary meningothelial proliferation: a case series and rethinking

Background

Lung cancer screening with computed tomography (CT) has been adopted worldwide. Consequently, there is an increase of some previously rarely reported lesions, like pleuropulmonary meningothelial proliferation (PMP), which included metastatic pulmonary meningiomas (MPMs), primary pulmonary meningiomas (PPMs) and minute pulmonary meningothelial-like nodules (MPMNs). To date, the understanding of the clinical management of PMP is limited.

Methods

We retrospectively searched PMP (MPMs, PPMs, and MPMNs) on the medical database (May 2005 to April 2019) of our department, and extracted the demographic and perioperative information. The last follow-up was in May 2019.

Results

A total of 78 patients, including 16 (20.5%) males and 62 (79.5%) females, were enrolled, with the median age as 61 (range, 27–78) years. There was 1 case with multiple MPMs, 4 cases with PPMs and 73 cases with MPMNs. On CT, MPMs manifested as round nodules with solid or part-solid components. PPM mainly presented as an isolated, round, solid, and well-circumscribed nodule, with or without lobulation. While MPMNs often showed as multiple, round, randomly-distributed, solid or partly-solid nodules, most of which were in tiny size. Histologically, MPM, PPM, and MPMN had similar morphological and immunohistochemical (IHC) features. As to the surgical outcomes, the case with multiple MPMs had undergone a progression after wedge resection and was in an active monitoring. And the four cases with PPMs and the five cases with MPMNs were all in regular surveillance.

Conclusions

PPM has variable radiological manifestations. But it can be histologically identified by the characteristic features. Although surgery is able to achieve satisfying prognosis, active observation is an alternative in selected cases due to the surgical invasiveness and the indolent nature of the disease.

Benign disease prone to be misdiagnosed as malignant pulmonary nodules: Minute meningothelioid nodules

Background

The lung is one of the most common target organs for malignant tumor metastasis. The existence of lung metastasis may have a decisive effect on the choice of treatment regimen. Minute pulmonary meningothelial‐like nodules (MPMNs) usually present as ground‐glass opacity or solid nodules, mimicking the imaging findings of malignant pulmonary nodules. This study summarizes the clinical, radiological, and pathological features of MPMNs to distinguish them from malignant pulmonary nodules.

Methods

The Guangdong Lung Cancer Institute Pathology Information System was searched using the key words “minute meningothelioid nodules” and “lung.” Patients who underwent pulmonary resection from 23 February 2009 to 31 May 2017 were included in the study. The 11th edition of Rosai and Ackerman's Surgical Pathology was used to confirm the diagnosis. The clinical, imaging, and pathological characteristics of MPMNs were recorded.

Results

Twelve patients had MPMNs. MPMNs were associated with cancerous or precancerous lesions (10/12), female gender (11/12), and non‐smokers (11/12). Four patients were misdiagnosed with malignant pulmonary nodules before surgery. Positron emission tomography‐computed tomography revealed an increased maximum standardized uptake value in one patient. Immunohistochemistry identified eight specimens positive for vimentin, EMA, and PR and negative for TTF‐1 and CK.

Conclusions

MPMNs tend to coexist with malignant tumors, mimicking the imaging findings of malignant pulmonary nodules, thus resulting in misdiagnosis. Dynamic monitoring or an invasive examination may help to distinguish MPMNs from malignant lesions.

Primary Pulmonary Meningioma With Rhabdoid Features

Only 1% to 2% of meningiomas have primary extrameningeal location, which is mostly head and neck region. Primary pulmonary meningiomas (PPMs) are even more uncommon with up to 50 cases reported in the literature. Only 5 cases of PPM with confirmed or possible malignancy have been previously described. Three-grade classification of meningiomas with the accordingly growing risk of aggressive behavior of the tumor has been proposed by the World Health Organization. As it is based on correlations between morphological and clinical features of intracranial meningiomas, the analogous prediction of ectopic tumors prognosis remains questionable due to scarce number of cases. In this article, we present a rare case of PPM with rhabdoid features (World Health Organization grade III), which lacked other signs of malignancy. The patient is doing well for 2 years after the thoracoscopic wedge resection without evidence of the disease recurrence.

Primary pulmonary meningioma: A rare case report of aspiration cytological features and immunohistochemical assessment

Ectopic meningioma is a generally rare type of benign tumor that very rarely occurs in the lung. Here, we report the cytological findings of a primary pulmonary meningioma with a particular focus on immunohistochemical (IHC) assessment. A healthy 60‐year‐old woman visited our hospital with an asymptomatic nodule in the right lower lung lobe. She had no particular past‐history and no other tumors in the central nervous system or elsewhere according to an imaging examination. Transbronchial fine‐needle aspiration cytology revealed clusters of spindle cells in a whorled formation and psammoma bodies. The tumor cells exhibited spindle‐shaped cytoplasm, small fusiform or round nuclei and numerous intranuclear cytoplasmic inclusions. IHC staining of the cytological specimen revealed that the tumor cells were positive for epithelial membrane antigen, negative for thyroid transcription factor‐1 and p40, and equivocal for claudin‐1. Progesterone receptor immunoreactivity of cytology specimen resulted negative at first by manual method but retrieved positive by an autostainer. Following segmentectomy, the pathological diagnosis was a meningothelial meningioma. The patient has remained well without recurrence for 36 months postoperatively. Because the cytological preparation exhibited characteristic findings of meningioma, a correct diagnosis based on pre‐operative cytological findings with appropriate IHC would be possible. Here, we report the cytological and IHC features of this case and highlight the importance of IHC‐quality assurance.

Brief report on similar mutational changes in neurofibromatosis type 2 gene in minute pulmonary meningothelial-like nodule and meningioma of the central nervous system

Introduction

Minute Pulmonary Meningothelial-like Nodules (MPMNs) are usually detected incidentally adjacent to lung cancer tissue. The pathogenesis is unknown. MPMNs reportedly share the status of neurofibromatosis (NF)-2 gene with meningiomas of the central nervous system.

Results

Immunohistochemical staining of two MPMNs revealed they were positive for epithelial membrane antigen (EMA), vimentin, CD56, and progesterone. We identified deletion of the NF-2 gene in two MPMNs and one CNS meningioma.

Conclusions

MPMN and CNS meningioma may develop via the same mechanism through NF-2 translocation. Further studies are required to elucidate the genetic similarities between these entities.

Methods

We used fluorescence in situ hybridization to explore the status of the NF-2 gene in MPMNs and compare it with that of CNS meningiomas. We used a commercially available locus-specific probe for the NF-2 region to analyze whole tissue sections of two MPMNs and two CNS meningiomas by fluorescence in situ hybridization.

Intranodal meningothelial proliferation in a patient with Cowden syndrome: a case report

Ectopic meningothelial proliferations are rare and can occur in a multitude of extracranial/spinal anatomic locations. Perineurioma is another uncommon entity that shares similar histological characteristics to those found in meningothelial proliferations. These include bland spindle cells with thin, bipolar nuclei; eosinophilic cytoplasm; and indistinct cell borders, arranged in short fascicles with whorl formation. Given their uncommon occurrence and shared histological and immunohistochemical features, their distinction can present a diagnostic challenge. Immunohistochemical studies can provide guidance when attempting to distinguish between these 2 lesions. Here, we present an unusual case of a patient with Cowden syndrome who was discovered to have a meningothelial proliferation within an axillary lymph node. To the best of our knowledge, this is the first case in which a meningothelial proliferation has been identified in a lymph node. Furthermore, the occurrence in a patient with Cowden syndrome is intriguing and raises the possibility of a pathogenetic link.

Primary Pulmonary Meningioma Simulating a Pulmonary Metastasis

Primary pulmonary meningiomas represent a rare tumor entity. Few cases have been reported in the English medical literature, and they have almost all been solitary and benign in nature, with the exception of several extremely rare cases. We report herein a case of PPM that raised suspicion of a pulmonary metastatic tumor initially, as it was depicted as a single, round, small, ground-glass opacity pulmonary nodule on a chest computed tomography scan, in a 55-year-old man with a history of buccal cancer. Increased awareness of the clinical and radiologic characteristics of this rare category can assist a multidisciplinary team to perform adequate management.