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

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.

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.

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.