Pulmonary meningothelial-like nodules: a genotypic comparison with meningiomas.
BACKGROUND
Minute pulmonary meningothelial-like nodules (MPMNs) are incidental interstitial pulmonary nodules. They share histologic, ultrastructural, and immunohistochemical features with meningiomas (MGs).


METHODS
Sixteen cases yielding 33 separate MPMNs and 10 cases of benign MG were studied. Immunohistochemical studies and 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 MG.


RESULTS
A total of 96.6% of MPMNs stained positive for vimentin, 33.3% for epithelial membrane antigen, 3% for S-100, and all were negative for cytokeratin and synaptophysin. Loss of heterozygosity (LOH) was identified in 25% of single MPMN affecting 3 genomic loci. No solitary MPMN had more than 1 LOH event. Multiple LOHs were seen only in MPMN-omatosis syndrome, where 33.3% of MPMNs showed LOH affecting 7 genomic loci. MG showed the highest frequency of LOH with major events seen at 22q (60%), 14q (42.8%), and 1p (44.4%) that were not shared by MPMN.


CONCLUSIONS
Isolated MPMN lacks mutational damage, consistent with a reactive origin. MPMN-omatosis syndrome might represent the transition between a reactive and neoplastic proliferation. MPMNs are different from MG based on the major molecular genetic events seen in their formation and progression.
Ionescu
Diana N
DN
Department of Pathology, Division of Anatomic Pathology, University of Pittsburgh Medical Center, Presbyterian University Hospital, Room A610, 200 Lothrop St., Pittsburgh, PA 15213, USA. ionescudn@msx.upmc.edu
Sasatomi
Eizaburo
E
Aldeeb
Dalal
D
Omalu
Bennet I
BI
Finkelstein
Sydney D
SD
Swalsky
Patricia A
PA
Yousem
Samuel A
SA
D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D004252:DNA Mutational Analysis; D005260:Female; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008577:Meningeal Neoplasms / Q000235:genetics; D008579:Meningioma / Q000235:genetics* / Q000473:pathology* / Q000648:ultrastructure; D008875:Middle Aged; D010236:Paraganglioma, Extra-Adrenal / Q000235:genetics* / Q000473:pathology* / Q000648:ultrastructure