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

Primary pulmonary meningioma and minute pulmonary meningothelial-like nodules: Rare pulmonary nodular lesions requiring more awareness in clinical practice

In this editorial, we comment on an article by Ruan et al published in a recent issue of the World Journal of Clinical Case. Pulmonary meningothelial proliferative lesions, including primary pulmonary meningiomas, minute pulmonary meningothelial-like nodules, and metastatic pulmonary meningiomas are rare pulmonary lesions. These lesions are difficult to differentiate from lung cancers based on clinical and imaging manifestations. Herein, we briefly introduce the clinical, imaging, and pathological characteristics of these lesions and discuss their pathogenesis to strengthen the current understanding of pulmonary meningothelial proliferative lesions in clinical diagnosis and therapy.

Pathological diagnosis and immunohistochemical analysis of minute pulmonary meningothelial-like nodules: A case report

BACKGROUND

Minute Pulmonary Meningothelial-like Nodules (MPMNs) are rare benign pulmonary nodules, which are more common in elderly women and have a higher detection rate in lung tissues of patients with lung malignant diseases. Its origin is not yet clear. At present, there are few reports on the diagnostic methods such as imaging and pathological manifestations of MPMNs. This article reports a 70-year-old female patient with pulmonary adenocarcinoma combined with MPMNs and reviews of the relevant literature.

CASE SUMMARY

A 70-year-old women was admitted to our institution with feeling sour in her back and occasional cough for more than 2 mo. Computerized electronic scanning scan and 3D reconstruction images in our institution showed there were multiple ground-glass nodules in both of her two lungs. The biggest one was in the apicoposterior segment of left upper lobe, about 2.5 mm × 9 mm in size. We performed thoracoscopic resection of the left upper lung apicoposterior segment of the patient, and the final pathological report was minimally invasive adenocarcinoma. Re-examination of high resolution computed tomography 21 mo after surgery showed multiple ground-glass nodules in both lungs, and a new ground-glass nodule was found in the superior segment of the right lower lobe. We took pathological biopsy of the right upper lung and right lower lung nodules for the patient under thoracoscopy. The histomorphology of the right lower lobe nodule showed multiple lesions in the lung tissue, and the small foci in the alveolar septum were distributed in mild form of the aggregation of short spindle cells. The immunohistochemistry showed that the lesion was epithelial membrane antigen (EMA) (+), somatostatin receptor 2a (SSTR2a) (+), S-100 (-), chromogranin A (-), Syn (-), cytokeratin (-) and HMB-45 (-). The final diagnosis was minimally invasive adenocarcinoma, accompanied by MPMNs. We recommend that patients continue to receive treatment after surgery and to do regular follow-up observations.

CONCLUSION

The imaging manifestations of MPMNs are atypical, histomorphology and immunohistochemistry can assist in its diagnosis. This article reviews the relevant literature of MPMNs immunohistochemistry and shows that MPMNs are positive for EMA, SSTR2a, and progesterone receptor.

[Recent Advances and Controversies in Minute Pulmonary Meningothelial-like Nodules]

Minute pulmonary meningothelial-like nodules (MPMNs) are benign small lesions in the lungs, with similar pathological characteristics to the meningeal epithelium. MPMNs have similar imaging manifestations to malignant tumors, which can lead to misdiagnosis in clinical practice. There is no consensus on the pathogenesis of MPMNs, with some suggest that MPMNs derive from reactive proliferation, while others suggest that MPMNs share a common origin and molecular mechanism with meningiomas in the central nervous system. Understanding the characteristics of MPMNs and studying their pathogenesis will help improve the understanding and diagnosis of MPMNs. In this article, we reviewed the clinical, pathological, imaging characteristics, differential diagnosis and pathogenesis of MPMNs. We also analyze the existing research advances regarding the pathogenesis and propose prospects for further research.
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Primary pulmonary meningioma with associated multiple micronodules: a case report and literature review

Primary pulmonary meningioma (PPM) is a rare and benign slow growing tumor with good prognosis. It often presents as an asymptomatic, well-circumscribed, solitary pulmonary nodule. Wedge resection is the management of choice for both diagnosis and treatment. Here, we report one case of PPM with increased fluorodeoxyglucose (FDG) uptake and associated micronodules, which was clinically suspicious for malignancy. The patient was a 60-year-old female who presented with persistent shortness of breath for 1 year. Chest computed tomography showed a 1.5-cm well-circumscribed homogenous nodule in the left upper lobe with increased FDG uptake and multiple smaller well-circumscribed micronodules scattered in both lungs. Left upper lobe wedge resection confirmed the diagnosis of PPM. PPM can deceptively mimic malignancy, so recognizing this rare entity and including it in the differential diagnoses of pulmonary nodules, especially with avid uptake of FDG, is crucial to avoid misdiagnosis and overtreatment.

Minute pulmonary meningothelial-like nodules: associations between computed tomography and pathology features

Background

Increased use of multislice computed tomography (CT) scans has revealed that minute pulmonary meningothelial-like nodules (MPMNs) showed as ground-glass nodules (GGNs) are frequent in patients. However, little is known about the incidence and fate of nodules. By using a cross-sectional design, this study compared the multislice CT signs and pathological results of MPMNs, and further used pathological results to explain the formation mechanism of the CT signs of MPMNs to improve the clinical understanding of the disease.

Methods

The clinicopathological data of 93 cases diagnosed as MPMNs in the Jiangsu Province Hospital from January 2016 to September 2019 and the Nanjing First Hospital from January 2017 to December 2019 were examined. The related literature was reviewed, and each case's age, gender, medical history, and preoperative CT examinations were classified. Based on CT signs, this study analyzed the imaging features, including size, shape, boundary, distribution, opacity, and their relationship with pulmonary blood vessels.

Results

A total of 13 cases had immunohistochemistry results among which the lesions showed consistent positive expression of vimentin (100%), followed by epithelial cell membrane antigen (92.3%) and progesterone (8%). The MPMNs mainly occurred in individuals aged 50-59 years (32.6%). Most patients (82.6%) had neoplastic disease. All nodules (100%) manifested with a round shape and well-demarcated borders on images. The size of the nodules on CT scans ranged from 2.5 to 5.0 mm, with an average size of 3.04±1.12 mm. Most nodules were subpleural (89.1%) and showed ground-glass opacity (97.8%). The follow-up results of postoperative clinical manifestations and chest CT examination were negative in 12 patients.

Conclusions

This study suggested that the pathological findings of MPMNs could explain the formation mechanism of the CT signs. The results can provide guidance for the diagnosis of the disease in the future.

Case Report: Clinicopathological Analysis of Minute Pulmonary Meningothelial-Like Nodules: Report of 7 Cases

Objective

To investigate the clinical manifestations, radiologic features, pathological features, and immunophenotype of minute pulmonary meningothelial-like nodules (MPMNs).

Method

This is a retrospective observational study. We collected the clinical data of 7 cases of MPMNs, and performed comprehensive characterization using a combination of clinical, morphological, radiologic and immunohistochemical assessments.

Results

Of the 7 cases of MPMNs, 6 were female and 1 was male. The median age was 55 years. All MPMNs were multiple in lung with the size from 0,01 to 0,5cm. Chest CT examination showed ground-glass attenuation or solid nodules. Four cases were concomitant with carcinoma and/or pneumonia, and 3 cases occurred alone. Four of the 7 patients had no obvious symptoms; 3 patients had chest pain or cough or shortness of breath or hemoptysis. Multiple white nodules were found macroscopically, and the diseased cells grew along the alveolar septum, with relatively normal morphology, rich cytoplasm, unclear cell boundary, and uniform nucleus with delicate chromatin and without atypia; and the diseased cells showed nest or whorls distribution. EMA, PR, CD56 and vimentin were positive in all cases by immunohistochemistry.

Conclusions

MPMNs are rare benign lesions in the lung, often multiple, usually less than 0.5cm in diameter, most of which have no obvious clinical symptoms. MPMNs are often found by chest CT, and occur independently or concomitant with other lesions. The positive immunohistochemical staining of EMA, PR, CD56, vimentin supports the diagnosis.

Primary pulmonary meningioma presenting as multiple lung nodules: A case report

Primary pulmonary meningioma (PPM) is a very rare and mostly benign disease. Although PPM is incidentally detected as a solitary pulmonary nodule on X-ray or chest computed tomography, it does not have unique radiological characteristics; thus, it is difficult to differentiate it from other lung tumors. A healthy 54-year-old man visited our hospital because of multiple variable-sized lung nodules. He had no contributive medical history and no abnormality that was suggestive of extrapulmonary malignancy. Video-assisted thoracoscopic wedge resection was undertaken for diagnosis, and the tumor cells were histopathologically confirmed as PPM. Brain magnetic resonance imaging revealed no intracranial tumor. The patient has been well and without any progression of the remaining lesions over 24 months. Here, we present the clinicopathological features of this case in which the patient's nodules were mistaken for multiple metastatic lung nodules.

[A pulmonary tumor that racks our brains!]

We report the case of a 74-year-old woman who, as part of the follow-up for two breast cancers, presented a 2cm long lung nodule. A microscopic examination of the biopsy under a scanner showed a proliferation of epithelial appearance but whose immunophenotypic profile did not permit a precise diagnosis (negativity of CK7, GATA3, TTF1, negative estrogen receptors but positive progesterone receptors). Wedge resection surgery was performed. Extemporaneous and definitive microscopic examination showed a well-defined lesion made up of lobules of cohesive-looking cells, frequently forming coils. The tumor cells showed some intranuclear inclusions and a few psammomas while the immunohistochemical study showed diffuse expression of EMA, SSTR2A and progesterone receptor markers and a low proliferation index. A diagnosis of a pulmonary localization of a meningioma was proposed. The radiological assessment of the entire neuraxis did not show any other lesion leading to the final diagnosis of primary intra-pulmonary meningioma. This is an exceptional tumor with a difficult histopathological diagnosis of biopsy material, which must familiar to the pathologists. It is associated with an excellent prognosis. Our observation aims to illustrate the macroscopic and microscopic aspects and to present the data from the recent literature review.