Minute Pulmonary Meningothelial-like Nodules Research Articles

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. .

Clinical, radiological, and pathological features of minute pulmonary meningothelial-like nodules and diffuse pulmonary meningotheliomatosis.

Minute pulmonary meningothelial-like nodules (MPMNs) and diffuse pulmonary meningotheliomatosis (DPM) are both rare lung diseases that involve the proliferation of cells of meningothelial origin in the lungs. However, few studies have focused on the clinical, pathological, and radiological features of MPMNs and DPMs. The clinicopathological data of 167 cases diagnosed as MPMNs and 13 cases diagnosed as DPM in the China National Center for Respiratory Medicine were examined. Based on clinical data, CT images, and morphological features, this study analyzed the similarities and differences between MPMNs and DPM. The detection rates of MPMNs and DPM were 1.9 and 0.15%, respectively. Compared to MPMNs, DPM patients were all women (100% vs. 79.4%, P = 0.066), had a younger age (51.4 ± 7.7 vs. 57.9 ± 8.5, P < 0.01), and had higher pulmonary function (P < 0.01 or P < 0.05). The chest CT of DPM patients showed diffuse ground-glass opacity nodules measuring 2.0-8.0 mm in diameter, with the number of nodules ranging from 40 to >600 per lung. There were no significant differences in nodule volume [28.0 (12.1, 65.1) mm3 vs. 28.7 (17.1, 48.9) mm3, P = 0.451] and CT values [-646.8 (-732.5, -514.5) Hu vs. -588 (-674, -480) Hu, P = 0.215] between MPMNs and DPM. MPMNs are characterized by reactive hyperplasia pulmonary nodules, which can be solitary or multiple. This study suggests that there are many different characteristics between patients with MPMNs and DPM. The limited findings challenge the notion that DPM is a rare subtype of MPMNS.

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

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. 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. 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. 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.

Diffuse Pulmonary Meningotheliomatosis: A Case Report

Abstract Introduction/Objective Diffuse pulmonary meningotheliomatosis (DPM) is a pulmonary disease characterized by the presence of widespread bilateral minute pulmonary meningothelial-like nodules (MPMNs). It is exceedingly rare and predominantly seen in females. The nodules are typically asymptomatic and detected incidentally on imaging. Methods/Case Report We present a case of a 57-year-old woman with a history of chronic cough and CT imaging findings of bilateral multiple ground-glass nodules. Wedge resections from the right upper and right lower lobes were obtained, which revealed gross changes suggestive of interstitial lung disease. Histologic evaluation of the wedges showed similar morphology, consisting of discrete areas with variable interstitial expansion of the stroma with ovoid/spindle cells, collagen, elastosis, and mild chronic inflammatory cells, in a somewhat perivascular pattern. Some areas were also cystic. This appeared in a background of emphysematous change and focal foreign body giant cell reaction to non-polarizable material. Immunohistochemical stains were diffusely positive for vimentin, EMA , and PR, and CD163 highlighted increased cells that were S100 and CD1a negative. Additionally, the ovoid/spindle cells were negative for desmin, SMM, HMB-45, HHV8, pan-CK, chromogranin, and multiplex SOX10-MART1. Results (if a Case Study enter NA) NA Conclusion Diffuse pulmonary meningotheliomatosis is a rare entity that requires sufficient histological evaluation to identify the ovoid/spindle cell component histologically and immunohistochemically. This disease should be considered in the differential for cases of diffuse interstitial pulmonary infiltrates. Few cases have been reported in the literature, requiring further research to understand the mechanisms of this disease and its clinical significance.

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

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

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

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. 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. 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. 79min 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 5.3mm 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 6months (13/29, 44.8%). The median pre-operative radiologic follow-up was 4.9months. Approximately 90% of patients underwent pulmonary surgery because of other malignant nodule on chest computed tomography scan (52/59, 88.1%). 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.

Minute pulmonary meningothelial-like nodules: rare lesions appearing as diffuse ground-glass nodules with cyst-like morphology.

Minute pulmonary meningothelial-like nodules (MPMNs) are often discovered incidentally in surgical or autopsy specimens of the lung (1). They usually manifest as single or multiple lesions, and rarely present as diffuse on computed tomography (CT) images. In this case report, we describe a patient diagnosed with MPMNs, which appeared as diffuse ground-glass nodules (GGNs). We also retrospectively review the clinical, pathological, and CT characteristics of patient diagnosed MPMNs to help improve the understanding of the disease and the accuracy of diagnosis.

DIFFUSE PULMONARY MENINGOTHELIOMATOSIS DIAGNOSED BY TRANSBRONCHIAL CRYOBIOPSY

SESSION TITLE: Medical Student/Resident Lung Pathology SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Minute pulmonary meningothelial-like nodules (MPMNs) are typically asymptomatic, solitary lesions incidentally noted on pathologic evaluation of lung tissue. However, diffuse, bilateral pulmonary involvement, termed diffuse pulmonary meningotheliomatosis (DPM), is exceedingly rare and has only been described in a small number of case studies. We report a case of a patient diagnosed with DPM via transbronchial cryobiopsy. CASE PRESENTATION: A 67-year-old non-smoking female with a history of scleroderma was referred for diffuse bilateral pulmonary nodules found on computed tomography (CT) scan of the chest with mosaicism concerning for diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH). Pulmonary function testing was notable for an isolated reduction in diffusing capacity at 58% with a normal echocardiogram. Two transbronchial cryobiopsy samples were obtained from the right lower lobe. Pathology revealed a meningothelial nodule. Immunohistochemistry was positive for epithelial membrane antigen (EMA) as well as progesterone receptor (PR) and negative for synaptophysin and chromogranin. Follow up imaging at 1 year demonstrated stability. Taken in context with her radiographic findings, the patient was diagnosed with DPM. DISCUSSION: DPM is an extremely rare condition characterized by MPMNs diffusely involving lung parenchyma. It predominantly affects females (2.2:1) with a median age of 59-62. DPM has no predilection for specific lobes, and it can be mistaken for metastatic or interstitial disease. Histologically, MPMNs appear as epithelioid cells arranged in small nests in pulmonary interstitium. Immunochemically, MPMNs tend to be positive for vimentin, EMA and PR and negative for S-100 protein, chromogranin A, and synaptophysin. Though the clinical significance of DPM is still unclear, prior studies have noted higher incidence among patients with underlying lung disease, particularly thromboembolism and malignancy. CONCLUSIONS: In summary, we present a case of DPM diagnosed by transbronchial cryobiopsy to highlight the importance of considering DPM in the differential of bilateral micronodular lung disease. Reference #1: Korn D, Bensch K, Liebow AA, Castleman B. Multiple minute pulmonary tumors resembling chemodectomas. Am J Pathol. 1960;37(6):641–672. Reference #2: Gaffey MJ, Mills SE, Askin FB. Minute pulmonary meningothelial-like nodules. A clinicopathologic study of so-called minute pulmonary chemodectoma. Am J Surg Pathol 1988; 12: 167-175. Reference #3: Gleason JB, Valentin R, Almedia P, Martinez N, Bejarano PA. Diffuse pulmonary meningotheliomatosis: a literature review of a rare diffuse parenchymal lung disease with unclear clinical significance. J Assoc Chest Physic 2017; 5: 18-25. DISCLOSURES: Speaker/Speaker's Bureau relationship with Boehringer-Ingelheim Pharmaceuticals Please note: $5001 - $20000 Added 04/07/2020 by Jaime Betancourt, source=Web Response, value=Honoraria Speaker/Speaker's Bureau relationship with Vapotherm, Inc Please note: $5001 - $20000 Added 04/07/2020 by Jaime Betancourt, source=Web Response, value=Honoraria No relevant relationships by I. Obi Emeruwa, source=Web Response No relevant relationships by Scott Oh, source=Web Response No relevant relationships by Megan Trieu, source=Web Response

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

BackgroundLung 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.MethodsWe 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.ResultsA 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.ConclusionsPPM 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.

Constant expression of somatostatin receptor 2a in minute pulmonary meningothelial-like nodules

AimsAlthough ultrastructural studies showed that minute pulmonary meningothelial-like nodules (MPMNs) cells closely resembled meningothelial cells, their immunophenotype has not been well characterised, partly due to their rarity.MethodsSomatostatin receptor 2a (SSTR2a)...

Clinicopathological features of diffuse pulmonary meningotheliomatosis

Objective To study the clinicopathological characteristics, immunophenotype, pathologic diagnosis and differential diagnosis of diffuse pulmonary meningotheliomatosis (DPM). Methods The clinical data, histological features and immunohistochemical results of three cases of DPM collected from January 2016 to May 2018 at Guangdong Provincial People′s Hospital were analyzed, and the relevant literature reviewed. Results The three DPM patients age was 53, 69 and 74 years. The lesions consisted of multiple minute pulmonary meningothelial-like nodules profusely involving the lungs. Microscopically, they showed typical morphology, characterized by medium-sized elongated tumor cells resembling meningothelial cells with whorled/nested clusters. The cells were uniform and had abundant eosinophilic cytoplasm with oval nuclei with delicate chromatin. Immunohistochemical staining showed tumor cells were diffusely and strongly positive for EMA, vimentin and PR, but were negative for CAM5.2, CgA, Syn, CK7 and TTF1. Conclusions DPM is extremely rare, and may be confused with primary interstitial pulmonary processes and metastatic malignant tumors of lung. Recognition of this entity is essential for pathologists to avoid misdiagnosis and unnecessary treatment. Key words: Lung diseases; Multiple pulmonary nodules; Diagnosis, differential; Immunohistochemistry; Diffuse pulmonary meningotheliomatosis

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

BackgroundThe 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.MethodsThe 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.ResultsTwelve 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.ConclusionsMPMNs 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.

A Case of Minute Pulmonary Meningothelial-like Nodule (MPMN) with Loss of the NF-2 Gene

A Case of Minute Pulmonary Meningothelial-like Nodule (MPMN) with Loss of the NF-2 Gene

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

IntroductionMinute 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.ResultsImmunohistochemical 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.ConclusionsMPMN 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.MethodsWe 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.

MINUTE PULMONARY MENINGOTHELIAL-LIKE NODULES ASSOCIATED WITH CONGESTIVE HEART FAILURE

SESSION TITLE: Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Report PRESENTED ON: 10/09/2018 07:30 am - 08:30 am INTRODUCTION: Minute pulmonary meningothelial-like nodules (MPMNs) are a distinguished entity of pulmonary nodules described as numerous, small and bilateral with a characteristic resemblance to meningiomas. CASE PRESENTATION: We present a 55-year-old African American female with past medical history of diastolic congestive heart failure (CHF), diabetes mellitus, chronic hypertension, and tobacco use disorder, who presented initially with increased productive cough with clear secretions, chest congestion and intermittent chest pain for few months. Pertinent findings on exam include decreased breath sounds at lung bases bilaterally with unremarkable laboratory tests. Pulmonary function tests favored a restrictive pattern with TLC of 3.61 L and a DLCO of 68% predicted with normal FEV1/FVC ratio. Computed tomography (CT) chest described innumerable bilateral small pulmonary nodules. Bronchoscopy with bronchoalveolar lavage was non-diagnostic. A video-assisted thoracoscopic surgical excision was completed. Pathology report confirmed meningothelial-like micronodules in the parenchyma, surrounding venules. They ranged in size from less than 0.1 cm to 0.7 cm and were reactive, related to parenchymal damage likely secondary to CHF. No evidence of malignancy was found. Microscopically, described as multiple whirled stellate nodules composed of monotonous proliferation of spindle cells with clear intranuclear pseudo-inclusions. Cells were positive for vimentin, progesterone receptor, and epithelial membrane antigen (EMA). Tuberculosis and fungal infections were excluded. Patient was started on aggressive CHF management with follow up CT in 3 months for monitoring progression. DISCUSSION: MPMNs are a rare entity of pulmonary lesions which was first described in 1960 by Korn et al on autopsy. Resembling meningiomas in character, MPMNs are considered reactive in nature but can also be malignant. They have been suggested to be the precursor lesions of primary pulmonary meningiomas. The incidence of MPMNs varies from 0.3% to 9.5% at autopsy or surgical specimens. It is more common in the 6th decade, favoring females. Associated with chronic lung disease, such as chronic thromboembolism (42 %), bronchiolitis-associated interstitial lung disease (26%), pulmonary adenocarcinoma (10%), and cardiac causes such as CHF, like in our patient. One case reported an association with breast cancer. No reports are found in pediatric lungs which might exclude a congenital origin.MPMNs are asymptomatic. They appear grossly as small persistent attenuated ground glass opacities bilaterally on chest CT. They range in size from 100 micrometer to 3 millimeter. Nodules larger than 1 cm are suggestive of malignancy. The gold standard for diagnosis is biopsy. Microscopically, they are described as nests of epitheliod cells arranged in “Zellballen” pattern around venules in the parenchyma. Immunohistologic profile is known to be positive for EMA, vimentin, progesterone receptor which suggests a role for sex-steroid hormones in their growth control, and recently CD56 similar to meningiomas. Conservative management of possible underlying cause is usually preferred but curative surgical excision is warranted in certain cases. Differential diagnosis includes miliary TB, metastatic carcinoma, pulmonary meningioma, pulmonary carcinoid tumors and rarely metastasis of primary intracranial malignant meningioma. CONCLUSIONS: MPMNs are small, numerous, bilateral pulmonary nodules that are likely reactive to other chronic conditions but can be associated with malignancy. Therefore, maintaining a high level of suspicion for this distinguished entity is important. Reference #1: Lee SK, Kim GJ, Kim YJ, Leem AY et al, Minute Pulmonary Meningothelial-Like Nodules Simulating Hematogenous Lung Metastasis: A Case Report ,Tuberc Respir Dis (Seoul). 2013 Aug; Published online 2013 Aug 30 Reference #2: Mukhopadhyay S1, El-Zammar OA, Katzenstein AL, Pulmonary meningothelial-like nodules: new insights into a common but poorly understood entity. Am J Surg Pathol. 2009 Apr. Reference #3: Korn D, Bensch K, Liebow A, Castleman B, Multiple Minute Pulmonary Tumors Resembling Chemodectomas, Am J Pathol. 1960 Dec. DISCLOSURES: No relevant relationships by Nadeen Audisho, source=Web Response No relevant relationships by Emmanuel Elueze, source=Web Response No relevant relationships by Monica Mutyala, source=Web Response No relevant relationships by Adam Yu, source=Web Response

Diffuse Pulmonary Meningotheliomatosis Presenting as Multiple Peribronchial Consolidations Containing Patent Air Bronchogram, Not Small Nodules: A Rare Manifestation for a Rare Disease

: Minute pulmonary meningothelial - like nodule (MPMN) is a common but poorly understood entity, which is benign or reactive in nature and has unknown etiology. MPMN can show single or multiple involvements associated with malignant conditions including pulmonary adenocarcinoma in some cases. The most common radiologic findings are non - specific small nodules, which often simulate pulmonary hematogeneous metastasis. We report a case of diffuse MPMNs presenting as multiple peribronchial consolidations containing patent air bronchogram, which is quite different from the previously reported radiologic findings.

P1.02-027 Minute Pulmonary Meningothelial-Like Nodules Presenting as Multiple Ground-Glass Density Nodules (GGNs): A Case Report

Minute pulmonary meningothelial-like nodules (MPMNs) are generally detected incidentally in resected lung specimens. Recently, with increased use of high-resolution computer tomography (HRCT), MPMNs have occasionally been detected before surgery. They may appear as mild restrictive lung disease or randomly distributed micronodules of ground-glass attenuation on HRCT.

Clinicopathologic features of minute pulmonary meningothelial-like nodules.

Purpose Minute pulmonary meningothelial-like nodules are incidentally discovered in lung specimens. We analyzed the clinicopathologic features of 14 cases identified in surgically resected lungs. Methods Among patients who underwent lung resection in our hospital from October 2007 to March 2016, 14 were found to have minute pulmonary meningothelial-like nodules. The clinical parameters, radiologic findings, and pathologic features of these patients were retrospectively reviewed using the medical records. Results The patients included 4 men and 10 women, with a mean age of 69 years (range 53-82 years). The coexisting main disease was adenocarcinoma in 8 patients, squamous cell carcinoma in 1, atypical adenomatous hyperplasia in 1, and metastatic pulmonary tumor in 3. In one patient, the minute pulmonary meningothelial-like nodules presented as multiple lung nodules on chest computed tomography. The median size of the nodules was 1.4 mm (range 0.3-6.0 mm). Similar to meningioma, one case had immunoreactivity to progesterone receptor and epithelial membrane antigen, although the minute pulmonary meningothelial-like nodules were not associated with a meningioma. Conclusions The relationship between minute pulmonary meningothelial-like nodules and meningioma should be investigated. If minute pulmonary meningothelial-like nodules are found on preoperative computed tomography, thoracoscopic lung biopsy is helpful for differential diagnosis.

Diffuse pulmonary meningotheliomatosis: A diagnostically challenging entity on fine‐needle aspiration cytology

Diffuse pulmonary meningotheliomatosis (DPM) is an exceedingly rare entity consisting of multiple minute pulmonary meningothelial-like nodules profusely involving the lungs. To the best of our knowledge, we present the first cytologic description of this uncommon lesion from a 57-year-old nonsmoking woman. Computerized tomographic-guided fine-needle aspiration cytology from a left upper lobe nodule showed whorled/nested clusters of elongated cells with oval nuclei, clear pseudonuclear inclusions, nuclear grooves/indentations, smooth nuclear contours, fine granular chromatin, inconspicuous nucleoli, and abundant fibrillary cytoplasm with indistinct cell borders. The subsequent pulmonary wedge resections confirmed the diagnosis of DPM. As this condition is exceptionally rare, familiarity with these cytologic features is of the essence to accurately establish this challenging diagnosis.