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Minute pulmonary meningothelial-like nodules

Author: Jian-Hua Qiao, M.D.

Editorial Board Member: Andrey Bychkov, M.D., Ph.D.

Editor-in-Chief: Debra L. Zynger, M.D.

Last author update: 2 July 2019

Last staff update: 13 October 2023

Copyright: 2019-2024, PathologyOutlines.com, Inc.

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Table of Contents

Cite this page: Qiao JH. Minute pulmonary meningothelial-like nodules. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumormpmn.html. Accessed April 26th, 2024.

Definition / general

Uncommon incidental pulmonary nodules composed of interstitial nodular proliferation of small oval or spindle shaped cells arranged in a zellballen nesting pattern (J Thorac Imaging 2002;17:227)

Essential features

Generally detected incidentally in resected lung specimens (Hum Pathol 2009;40:678)
Occasionally detected on thin section computed tomography (Hum Pathol 2009;40:678)
More common in patients with malignant pulmonary tumors, especially lung adenocarcinoma, than benign disease (Hum Pathol 2009;40:678)
No significant difference in clinicopathologic factors between patients with single and multiple nodules, except for the size of each nodule (Hum Pathol 2009;40:678)

Terminology

Pulmonary chemodectomas were first described by Korn et al. in 1960 (Am J Pathol 1960;37:641)
In 1988, Gaffey et al. proposed to change the name of pulmonary chemodectomas to minute meningothelial-like nodules (Am J Surg Pathol 1988;12:167)
Terminology includes
- Pulmonary meningothelial-like nodules (PMLNs)
- Minute pulmonary meningothelial-like nodules (MPMNs)
- Pulmonary chemodectoma
- MPMN-omatosis syndrome
- Diffuse pulmonary meningotheliomatosis (DPM)

ICD coding

ICD-10: R91.1 - solitary pulmonary nodule

Epidemiology

F > M (10.7% versus 4.5%) (Hum Pathol 2009;40:678)
Most frequent in the sixth decade
Absent in fetuses, infants and children, indicating that they do not represent congenital rests
Reported incidence is 0.3 to 9.5% at autopsy or in surgical specimens (Korean J Pathol 2012;46:87)

Sites

Present in all lobes; incidence is not different between lobes (Hum Pathol 2009;40:678)

Pathophysiology

Usually asymptomatic but can occasionally manifest as mild restrictive lung disease (Respiration 2013;86:145)

Etiology

Although recognized for decades, their nature and significance remain uncertain (Am J Surg Pathol 2009;33:487)

Clinical features

Patients are usually asymptomatic, as the behavior is benign (Tuberc Respir Dis (Seoul) 2013;75:67)

Diagnosis

Often identified as incidental findings in histopathological lung sections or in high resolution CT scans conducted for unrelated causes (Korean J Pathol 2012;46:87)

Radiology description

Thin section chest CT reveals randomly distributed, well defined ground glass appearance micronodules, which may simulate metastatic disease (J Comput Assist Tomogr 2001;25:311)

Radiology images

Images hosted on other servers:

CT scan with
1 cm nodule

Positron emission tomography

Chest film shows bilateral diffuse nodules

CT scan shows nodules

Prognostic factors

Found more often in patients with malignant pulmonary tumors, especially lung adenocarcinoma (Korean J Pathol 2012;46:87)

Case reports

52 year old man with 1 cm nodule in the left lower lobe discovered on CT scan (Tuberc Respir Dis (Seoul) 2013;75:67)
56 year old woman with left mastectomy for breast cancer (Nihon Kokyuki Gakkai Zasshi 2002;40:499)
65 year old diabetic woman with breast cancer and smoking history (Korean J Pathol 2012;46:87)
74 year old asymptomatic woman with incidentally detected diffuse bilateral pulmonary nodules (Respirol Case Rep 2017;5:e00238)
75 year old woman with a history of invasive rectal adenocarcinoma (Ann Saudi Med 2013;33:400)
Multiple incidentally detected, randomly distributed, cavitating micronodules (J Comput Assist Tomogr 2010;34:780)

Treatment

Although curative surgical excision is sometimes needed, these usually run a benign course and conservative treatment is favored (Tuberc Respir Dis (Seoul) 2013;75:67)

Gross description

1 - 3 mm, tan to yellow, pleural or parenchymal nodules (Am J Surg Pathol 1988;12:167)

Microscopic (histologic) description

Characteristic nests of bland spindle cells with pale eosinophilic cytoplasm expand alveolar septa
Larger lesions connected by intervening collagen, often imparting a stellate configuration
Smaller lesions have closely apposed nests with mildly thickened alveolar septa (Am J Surg Pathol 1988;12:167)

Microscopic (histologic) images

Contributed by Jian-Hua Qiao, M.D.

Interstitial nests of spindle cells

CD56

EMA

Vimentin

AE1 / AE3

CK5 / 6

Virtual slides

Images hosted on other servers:

Pulmonary meningothelial-like nodule

Cytology description

Single as well as clusters of bland spindle cells are present in aspirate smears
However, marked cellular atypia is often seen with cytology diagnosis of atypical / suspicious for malignancy / positive for malignancy
Immunohistochemistry of cell block will rule out the possibility of carcinoma or squamous cell carcinoma since the spindle cells are negative for pankeratin (AE1 / AE3), p63 and p40

Cytology images

Contributed by Jian-Hua Qiao, M.D.

Papanicolaou (Pap) stain

p63

p40

Positive stains

Negative stains

Pankeratin (AE1 / AE3), CK5 / 6, estrogen receptor / ER, HER2 nonbreast, GCDFP-15, p63, p40, synaptophysin

Electron microscopy description

Ultrastructural features include interdigitating cellular junctions, desmosomes and scattered intracytoplasmic filaments (Korean J Pathol 2012;46:87)

Electron microscopy images

Images hosted on other servers:

Interdigitating cells and desmosomes

Molecular / cytogenetics description

Mutational analyses were performed on microdissected tissue using 20 polymorphic microsatellite markers targeting 11 genomic regions in an effort to identify genetic similarities of MPMN and meningioma (Am J Surg Pathol 2004;28:207)
Loss of heterozygosity was identified in 25% of single MPMN affecting 3 genomic loci
- No solitary MPMN had > 1 loss of heterozygosity event
- Multiple loss of heterozygosity were seen only in diffuse pulmonary meningotheliomatosis (MPMN-omatosis syndrome), where 33.3% of MPMNs showed loss of heterozygosity affecting 7 genomic loci
- Meningioma showed the highest frequency of loss of heterozygosity with major events seen at 22q (60%), 14q (42.8%) and 1p (44.4%) that were not shared by MPMN
- MPMNs are different from meningioma based on the major molecular genetic events seen in their formation and progression
NF2 deletion similar to meningioma found in a limited series (Oncotarget 2018;9:36012)

Sample pathology report

Left lung, mass, CT guided needle core biopsy:
- Minute pulmonary meningothelial-like nodule
- Negative for malignancy
- Adjacent lung parenchyma with mild interstitial fibrosis

Differential diagnosis

Metastatic carcinoma: usually positive for pankeratin (AE1 / AE3)
Pulmonary carcinoid tumors (or pulmonary tumorlets for lesions < 5 mm): positive for pankeratin (AE1 / AE3), synaptophysin and INSM1 (Histopathology 2018;72:1067)
Paraganglioma: positive for neuron specific enolase, chromogranin, synaptophysin, CD57 and GFAP
Pulmonary meningiomas: clonal neoplastic lesions, which usually present as lung masses rather than minute nodules

Additional references

Virchows Arch 2002;440:543

Board review style question #1

An 80 year old Caucasian woman had a thyroid mass and a 1 cm pulmonary lesion. CT guided transthoracic needle biopsy was performed to rule out metastatic tumor. Microscopic examination of core needle biopsy tissue reveals the following lesion. What is your diagnosis?

Metastatic thyroid papillary carcinoma
Minute pulmonary meningothelial-like nodule
Pulmonary carcinoid tumor
Pulmonary meningioma
Pulmonary paraganglioma

Board review style answer #1

B. Minute pulmonary meningothelial-like nodule. Microscopic lesion is classic of pulmonary meningothelial-like nodule, with irregular and uncircumscribed interstitial nests of spindle cells, morphologically similar to meningothelial cells.

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Reference: Minute pulmonary meningothelial-like nodules

Board review style question #2

Sometimes, immunohistochemistry is necessary to work up this spindle cell lesion. Pulmonary meningothelial-like nodule is most likely positive for which of the following immunostains?

CD56
CK5 / 6
ER
Pankeratin (AE1 / AE3)
Synaptophysin

Board review style answer #2

A. CD56. Pulmonary meningothelial-like nodule is positive for CD56, EMA, progesterone receptor / PR and vimentin.

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Reference: Minute pulmonary meningothelial-like nodules

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