Comprehensive Genomic and Transcriptomic Analysis of Sclerosing Pneumocytoma.

Sclerosing pneumocytoma is a rare and distinct lung neoplasm whose histogenesis and molecular alterations are the subject of ongoing research. Our recent study revealed that AKT1 internal tandem duplications (ITD), point mutations, and short indels were present in almost all tested sclerosing pneumocytomas, suggesting that AKT1 mutations are a major driving oncogenic event in this tumor. Although the pathogenic role of AKT1 point mutations is well established, the significance of AKT1 ITD in oncogenesis remains largely unexplored. We conducted comprehensive genomic and transcriptomic analyses of sclerosing pneumocytoma to address this knowledge gap. RNA-sequencing data from 23 tumors and whole-exome sequencing data from 44 tumors were used to obtain insights into their genetic and transcriptomic profiles. Our analysis revealed a high degree of genetic and transcriptomic similarity between tumors carrying AKT1 ITD and those with AKT1 point mutations. Mutational signature analysis revealed COSMIC signatures 1 and 5 as the prevailing signatures of sclerosing pneumocytoma, associated with the spontaneous deamination of 5-methylcytosine and an unknown etiology, respectively. RNA-sequencing data analysis revealed that the sclerosing pneumocytoma gene expression profile is characterized by activation of the PI3K/AKT/mTOR pathway, which exhibits significant similarity between tumors harboring AKT1 ITD and those with AKT1 point mutations. Notably, an upregulation of SOX9, a transcription factor known for its involvement in fetal lung development, was observed in sclerosing pneumocytoma. Specifically, SOX9 expression was prominent in the round cell component, whereas it was relatively lower in the surface cell component of the tumor. To the best of our knowledge, this is the first comprehensive investigation of the genomic and transcriptomic characteristics of sclerosing pneumocytoma. Results of the present study provide insights into the molecular attributes of sclerosing pneumocytoma and a basis for future studies of this enigmatic tumor.

Characteristics of Metastatic and Nonmetastatic Pulmonary Sclerosing Pneumocytomas: A Clinicopathological Study of 68 Cases and 15 Reported Metastatic Cases.

To characterize the clinicopathologic features of pulmonary sclerosing pneumocytoma (PSP) and compare these features between the tumors with and without metastasis, 68 cases of PSP (1/68 [1.47%] with metastasis) diagnosed from 2009-2022 in our hospital and 15 previously reported metastasizing cases were studied. There were 54 female patients and 14 male patients, with age ranging from 17 to 72 years and tumor size ranging from 0.1 to 5.5 cm (mean, 1.75 cm). In all, 85.4% of the cases presented with ≥2 patterns, including papillary, sclerotic, solid, and hemorrhagic. Thyroid transcription factor 1, epithelial membrane antigen, CKpan, and CK7 were expressed in surface cells in 100% of the cases and napsin A was expressed in 90% of the cases. Stromal cell expression of these markers occurred in 100%, 93.9%, 13.5%, 13.8%, and 0% of the cases, respectively. Of the 16 PSP cases with metastasis, 8 were female patients and 7 were male patients, with age ranging from 14 to 73 years. The tumor size ranged from 2.5 to 12 cm (mean, 4.85 cm). Forty-five of the cases were negative for BRAF V600E immunostaining and 6 were focally weak positive, in which fluorescent PCR tests showed no detectable mutations. There were significant differences in gender, age, and tumor size between PSP cases with and without metastasis. No BRAF V600E mutation was found in patients with PSP. AKT1 p.E17K mutations were detected in both the primary lung tumor and the lymph node metastatic tumor of our PSP case with lymph node metastasis. In conclusion, PSP is an uncommon pulmonary neoplasm with significant female predilection and has distinct morphologic and immunohistochemical characteristics. The BRAFV600E mutation was not detectable in patients with PSP and thus may not involve in its tumorigenesis. Most PSP tumors are benign, with a minority exhibiting potential for metastasis and malignant behavior.

Pulmonary sclerosing pneumocytoma masquerading adenocarcinoma with co-existing BRAF V600E and PTEN mutation.

We report a case of a massive primary sclerosing pneumocytoma (PSP) involving the right lower lobe adhering esophagus with small synchronous PSP on the superior segment of the left lower lobe with concurrent mutation for B-RAF proto-oncogene, serine/threonine kinase (BRAF V600E), and phosphatase and tensin homolog (PTEN) gene in a young female. She underwent right lower lobectomy and mediastinal lymph node dissection under single lung ventilation with tumor-free margins on diagnosis-based findings of preoperative computed tomography-guided biopsy and positron emission tomography. Histopathology was suggestive of PSP-papillary variant with concurrent mutation of BRAF V600E and PTEN genes. Post-operative follow-up at four weeks was uneventful. She has to undergo wedge resection for the contralateral disease after six weeks following recovery from the first surgery.

Molecular Genetic Landscape of Sclerosing Pneumocytomas.

OBJECTIVES: Sclerosing pneumocytomas are rare pulmonary neoplasms that are typically benign. However, rare patients experience progressive disease, and therapy targeting specific genetic underpinnings could be an attractive therapeutic option. Recent studies have found recurrent AKT 1 mutations in sclerosing pneumocytoma, but little is known about whether oncogenic fusion genes may also be present. METHODS: To better understand the genetic background, 10 sclerosing pneumocytomas were subjected to next-generation sequencing cancer mutation panel testing (n = 9) and/or RNA sequencing (n = 3). The patients were all women (average age, 47 years; range, 17-74 years). RESULTS: Eight patients had solitary sclerosing pneumocytomas, while one had two tumors, and one had many bilateral tumors. Recurrent mutations were noted in genes involved in the mTOR pathway, including AKT1, PIK3R1, and PTEN. AKT1 alterations were particularly common, present in 78%. No recurrent genetic fusions were identified. The patient in our study with multiple bilateral lesions was treated with the mammalian target of rapamycin (mTOR) inhibitor everolimus, with no objective radiographic evidence of treatment response after 4 months. CONCLUSIONS: Our data further support that abnormal activation of the mTOR pathway is a consistent genetic event in sclerosing pneumocytoma. This warrants further exploration to determine if mTOR pathway inhibitors may be effective in patients with metastatic or recurrent disease.

AKT1 internal tandem duplications and point mutations are the genetic hallmarks of sclerosing pneumocytoma.

Sclerosing pneumocytoma is a unique benign neoplasm of the lungs. The molecular alterations in sclerosing pneumocytoma are not well understood. In a previous whole-exome sequencing study, recurrent AKT1 point mutation was observed in about half of the cases of sclerosing pneumocytoma. However, in the remaining half, cancer-related mutations have still not been identified. In this study, we first analyzed the raw sequence data from the previous whole-exome sequencing study (PRJNA297066 cohort). Using Genomon-ITDetector, a special software for detection of internal tandem duplications, we identified recurrent internal tandem duplications in the AKT1 gene in 22 of the 44 tumor samples (50%). All the cases positive for AKT1 internal tandem duplications lacked AKT1 point mutations. Next, we performed targeted next-generation sequencing in an independent cohort of sclerosing pneumocytoma from our hospital (VGH-TPE cohort), and again identified recurrent AKT1 internal tandem duplications in 20 of the 40 (50%) tumor samples analyzed. The internal tandem duplications resulted in duplications of 7 to 16 amino acids in a narrow region of the Pleckstrin homology domain of the AKT1 protein. This region contains the interaction interface between the Pleckstrin homology and kinase domains, which is known to play a critical role in the activation of the AKT1 protein. Moreover, we found that AKT1 internal tandem duplications were mutually exclusive of other forms of AKT1 mutations, including point mutations and short indels. Taking all forms of AKT1 mutations together, we detected AKT1 mutations in almost all the sclerosing pneumocytomas in our study (PRJNA297066 cohort: 41 out of 44 cases, 93%; VGH-TPE cohort: 40 out of 40 cases, 100%). Our results suggest that AKT1 mutation is the genetic hallmark of sclerosing pneumocytoma. These results would help in better understanding of the pathogenesis of sclerosing pneumocytoma.

Identification of the BRAF V600E mutation in a patient with sclerosing pneumocytoma: A case report.

OBJECTIVES: Sclerosing pneumocytoma (sclerosing hemangioma, SP) is a rare benign tumor of the lung with a low risk of recurrence. The genomic profile of SP is not well-known. Here we report gene mutation findings in a 17-year-old girl with SP. MATERIALS AND METHODS: Immunohistochemistry (IHC), next-generation sequencing (NGS), and sanger sequencing were performed on the tumor tissue of this patient for pathological diagnosis and gene mutation analysis. RESULTS AND CONCLUSION: Two mutations were identified in the tumor tissue by NGS and sanger sequencing: AKT1 E17K and BRAF (B-Raf proto-oncogene, serine/threonine kinase) V600E. This is the first case report of a BRAF V600E mutation in a patient with SP. This discovery extends our understanding of the pathogenesis of SP, and suggests the need for future testing of BRAF V600E in this rare tumor type.

Genome profile in a extremely rare case of pulmonary sclerosing pneumocytoma presenting with diffusely-scattered nodules in the right lung.

BACKGROUND: Pulmonary sclerosing pneumocytoma (PSP) typically presents solitary and peripheral mass, while only rarely cases display unusual multiple lesions. We reported a extremely rare case of PSP with diffusely-scattered nodules in the right lung. CASE PRESENTATION: Diffusely round-shaped nodular shadows in the right lung were found by CT scan in a 31-year-old Chinese woman. The patient undergone the right pneumnectomy. Grossly, numerous small nodules, up to 2.5 cm in greatest dimension were identified in the upper, middle and lower lobes of the right lung. Histologically, the tumor presented the typical features of PSP, with a variable proportion of solid, sclerotic and papillary patterns. Immunohistochemical staining further revealed that cuboidal surface epithelial cells were positive for TTF-1, EMA, AE1/3 and vimentin (partially), and round or polygonal cells expressed TTF-1, vimentin, EMA (weakly), synaptophysin (partially), progesterone receptor (partially), and estrogen receptor (scatteredly). The patient has been followed up for 83 months after surgery by annual chest CT and no new lesions are detected in her left lung and other organs. The whole-exome sequencing identified 15 somatic mutations genes (MEGF6, DNAH5, AKT1, GPRIN2, PIK3AP1, FBXO40, HERC1, VPS16, MORN1, ZNF474, CTNNB1, ZNF251, TSC1, ATM, KDR). Pathway analysis showed possible pathways like the components of CTNNB1, AKT1, and TSC1 mutations in the PI3K/AKT signalings and AKT1, KDR and ATM in VEGF signaling pathway and AKT1 activation seemed closely related with these pathways. CONCLUSION: According to our and previous data, PSP with diffuse or multiple lesions is very rare, and the patients are most commonly seen in women in Asian countries. The misdiagnosis rate by clinical and intraoperative frozen-section assessment is high because of the multiple nodules in the lung and its confusing histological features. Long time follow up indicates surgical resection should not be considered as the preferred strategy for treating multiple PSP in the intralobar sites. AKT1 activation may contribute to the development of PSP while the pathogenesis of diffuse or multiple PSP still needs to be further analyzed.

Expression and significance of stem cell markers in pulmonary sclerosing haemangioma.

AIMS: The two major types of cells of pulmonary sclerosing haemangioma (PSH) with the same origin show significant differences in morphological phenotype. Whether these differences are caused by their different differentiation status is still uncertain. The aim of this study was to analyse their differentiation status by detecting the expression of several stem cell markers in PSH. METHODS AND RESULTS: The expression of stem cell markers was examined by using streptavidin peroxidase (SP) immunohistochemisty in 45 PSH specimens. Also, the two types of cells were, respectively, captured by laser capture microdissection (LCM) from 28 PSH specimens, and total RNA was then extracted followed by reverse transcription-polymerase chain reaction (RT-PCR). The results demonstrated that the expression rates of ABCG2, Notch1 and Notch3 in polygonal cells were significantly higher than those in cuboidal cells (P < 0.05), and the expression levels of ABCG2, Notch3 and Jagged1 in polygonal cells were clearly higher than those in cuboidal cells (P < 0.05). CONCLUSION: The data obtained provided evidence that the two types of cells in PSH may be different in differentiation status. The differentiation difference between the two types of cells might lead to variation in their morphological phenotype.

Comparison of genetic and epigenetic alterations at 11 tumor suppressor loci in pulmonary sclerosing hemangioma and adenocarcinoma.

Pulmonary sclerosing hemangioma (SH) is an unusual tumor of pneumocytic origin. Morphologically, SH can mimic pulmonary adenocarcinomas. Here, the authors compared genetic and epigenetic aberrations in SH with those in pulmonary adenocarcinoma. Clinicopathologic characteristics, microsatellite alterations, and CpG island methylation were analyzed in pulmonary SHs (n = 24) and adenocarcinomas (n = 34) to compare their patterns of molecular abnormalities. SHs were also analyzed immunohistochemically to characterize the expression status of proteins involved in basic biologic processes. The clinical presentation of SH cases was generally benign. Both cell types of SH stained positive for thyroid transcription factor 1 (TTF-1), epithelial membrane antigen (EMA), ß-catenin, E-cadherin, and vascular endothelial growth factor (VEGF). Allelic imbalances in D3S1283, D3S1234, D3S1300, D3S1285, TP53, D17S938, and D9S179 were less frequent in SH than in adenocarcinoma; rates of allelic imbalances in D20S170 and D21S1446 were not significantly different. In SH, CpG island methylation frequencies of p16(INK4a) (0.0%) and RASSF1A (12.5%) were significantly lower than those in adenocarcinoma (29.4% and 38.2%, respectively); the frequencies of HOX D9, D11, and D13 gene methylation in SH were 37.5%, 33.3%, and 33.3%, respectively. The results show that pulmonary SH and adenocarcinoma share similar genetic and epigenetic aberrations, but also exhibit significant differences, especially in tumor suppressor genes.

Determination of clonal status of pulmonary sclerosing hemangioma with X-chromosome inactivation mosaicism and polymorphism of phosphoglycerate kinase and androgen receptor genes.

It has been reported that both polygonal and cuboidal cells in pulmonary sclerosing hemangioma (PSH) are monoclonal in origin and represent a variable differentiation from a common progenitor cell. However, it remains unclear about the clonality of the entire PSH lesion composed of these two types of cells. Thus, we analyzed the clonality of 22 cases of PSH and the relationship between the entire PSH and two types of cells using laser microdissection and X-chromosomal inactivation mosaicism and polymorphism at the phosphoglycerate kinase (PGK) and androgen receptor (AR) loci in female somatic cells. The results demonstrated all 22 cases of PSH showed typical histopathologic characteristics, including characteristic round or polygonal cells within the stroma and surface cuboidal cells lining the papillary projections or cystic spaces. The rates of polymorphism were 31.8% (7/22) and 86.3% (19/22) for the PGK and AR gene, respectively. After digestion by Hpa II or Hha I, one of two PCR amplification bands disappeared from all the samples, while the other band was retained, indicating neoplastic characteristics. Thus, we concluded that the entire PSH lesion, polygonal and cuboidal cells were neoplastic hyperplasia and originated from a common progenitor cell.

So-called sclerosing hemangioma of lung: current concept.

Sclerosing hemangioma of the lung is a rare neoplasm with polymorphic histologic features. Despite various patterns, there are 2 unifying cellular components: "surface cells" and "round cells." Although histogenesis has been debated for decades, most ultrastructural, immunocytochemical, and molecular studies strongly indicate a neoplastic epithelial derivation for both cellular components. Herein, we present a review of sclerosing hemangioma and summarize the essential data regarding histologic, cytologic, and ancillary findings of this distinctive pulmonary neoplasm.

Cytogenetic study of a pulmonary sclerosing hemangioma.

Pulmonary sclerosing hemangioma (PSH) is an uncommon benign tumor that presents as a solitary asymptomatic and slow-growing nodule. It occurs in both young and old persons; peak incidence is in the fifth decade. Both sexes are affected by this tumor, but women more frequently than men. On histological examination, PSH shows prominent sclerotization and vascularization of the tissue. Recent studies conclude that PSH derives from type II pneumocytes, but the potential for progression and histogenesis remains controversial. We report a case of pulmonary sclerosing hemangioma in a 61-year-old woman with a neoplastic node 1 cm in diameter. The karyotype was 46,XX,t(8;18),der(14;15),+14 in all the cells analyzed. PTEN (10q23) and IgH (14q32) probes were analyzed in interphase nuclei and paraffin-embedded tissues of tumor cells. These chromosome abnormalities could provide information about the relationship of genetic changes to the biological properties of sclerosing hemangioma tumors.

p53 protein expression and genetic mutation in two primary cell types in pulmonary sclerosing haemangioma.

AIMS: To investigate the significance of p53 protein expression and genetic mutations in two primary cell types in pulmonary sclerosing haemangioma (PSH). METHODS: p53 protein expression in polygonal cells and cuboidal cells in 19 patients with PSH was detected using immunohistochemistry. The two major cell types were captured using laser capture microdissection technology. Mutations in the p53 gene (exons 5-8) were examined using single-stranded conformation polymorphism and DNA sequencing analysis. RESULTS: p53 protein expression and gene mutations were observed in 15.8% (3/19) of cases. In these cases, p53 protein was expressed in the nucleus of both cell types, with higher expression levels and mutation rates in polygonal cells than in surface cuboidal cells. Two cases showed mutation only in the polygonal cells, while one case showed double (separate) mutations in both the polygonal and cuboidal cells. CONCLUSIONS: p53 mutation was exhibited in PSH. The mutation rate in polygonal cells was higher than that in surface cuboidal cells.

Frequent nuclear expression of beta-catenin protein but rare beta-catenin mutation in pulmonary sclerosing haemangioma.

BACKGROUND: Pulmonary sclerosing haemangioma (PSH) is an uncommon tumour that is composed of glandular/papillary lining cells and polygonal cells. The biological behaviour of this tumour has been investigated; however, the molecular pathogenesis of PSH remains unknown. AIMS: To characterise the role of the Wnt/beta-catenin pathway in the genesis of PSH. METHODS: 37 PSH samples were investigated immunohistochemically for detection of the beta-catenin protein and direct sequencing of exon 3 of the beta-catenin gene. RESULTS: Nuclear expression of beta-catenin was found in the lining component of 23 tumours (62%) and in the polygonal component of 11 tumours (30%). The expression of beta-catenin was stronger in the lining component, but weaker in the polygonal component. Interestingly, all the tumours with expression of beta-catenin in the polygonal component also expressed beta-catenin in the lining component. However, mutation of exon 3 of the beta-catenin gene was detected in only one tumour that expressed nuclear beta-catenin in lining and polygonal components. CONCLUSIONS: The Wnt/beta-catenin pathway is involved in the genesis of PSH, but mutation of exon 3 of the beta-catenin gene rarely contributes to the activation of the Wnt/beta-catenin pathway in PSH.

Role of the PI3K/Akt, mTOR, and STK11/LKB1 pathways in the tumorigenesis of sclerosing hemangioma of the lung.

Although the histogenesis of sclerosing hemangioma (SH) of the lung is now thought to be respiratory epithelial in origin, the genetic abnormalities that mediate its development are not known. Because pathophysiology of several syndromes associated with benign tumors may converge on the tuberous sclerosis complex (TSC), serine/threonine kinase 11 (STK11), and mammalian target of rapamycin (mTOR) pathways, the purpose of the present paper was to investigate their roles in the development of SH. Semiquantitative immunohistochemical analysis was done to assess the expression of phospho-mTOR, phospho-S6 ribosomal protein, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), phospho-Akt, STK11, tuberin, hamartin, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor-1alpha (HIF-1alpha) in 19 cases of typical SH. To determine whether genetic alteration of STK11 is involved in the development of SH, all encoding exons of STK11 were analyzed by polymerase chain reaction (PCR) amplification and direct sequencing of genomic DNA of six specimens. The six specimens were also investigated for whether promoter hypermethylation exists as an alternative inactivating mechanism for STK11. All specimens showed moderate to marked reaction to phospho-S6 ribosomal protein and PTEN; 16 specimens (84%) showed slight to moderate reaction to phospho-mTOR, negative reaction to STK11, and slight to moderate reaction to hamartin; 11 (58%) showed slight to moderate reaction to phospho-Akt; 18 (95%) showed slight to moderate reaction to tuberin and positive reaction for HIF-1alpha; and 17 (90%) showed moderate reaction to VEGF. No somatic mutation of STK11 was found and the six specimens were unmethylated in the promoter region. These data imply that aberrant mTOR signaling may play a role in the development of SH, and its vascular nature may be due partially to high levels of VEGF caused by dysregulation of mTOR signaling.

Gene expression and clonality analysis of the androgen receptor and phosphoglycerate kinase genes in polygonal cells and cuboidal cells in so-called pulmonary sclerosing hemangioma.

The histogenesis of polygonal cells and cuboidal cells in so-called pulmonary sclerosing hemangioma remains unclear. To understand their histogenesis, polygonal and cuboidal cells were obtained from pulmonary sclerosing hemangioma tissue using a laser capture microdissection technique. Genomic DNA and total RNA were extracted and mRNA levels of cytokeratin, epithelial membrane antigen, vimentin, surfactant protein B, thyroid transcription factor-1, synaptophysin, and chromogranin-A were analyzed by RT-PCR. DNA was digested with the methylation-sensitive enzymes HhaI or HpaII, followed by nested PCR of the androgen receptor and phosphoglycerate kinase genes. Samples with polymorphisms were identified and a clonality analysis was performed. The cytokeratin, epithelial membrane antigen, and surfactant protein B genes were clearly expressed in cuboidal cells, while the vimentin and synaptophysin genes were clearly expressed and the epithelial membrane antigen gene was weakly expressed in polygonal cells. Thyroid transcription factor-1 was expressed in both cell types, while neither cell type expressed chromogranin-A. Clonality analysis showed the same loss of allele in both cell types (clonality ratio=0) or an unbalanced methylation pattern (clonality ratio<0.25). Polygonal and cuboidal cells in pulmonary sclerosing hemangioma exhibited a uniform pattern of monoclonality, indicating that both cell types are highly likely to originate from a common precursor. The differences in their morphological phenotype might result from their different mature status.

Microsatellite and EGFR, HER2 and K-RAS analyses in sclerosing hemangioma of the lung.

Sclerosing hemangioma (SH) is an uncommon pulmonary tumor thought to derive from primitive respiratory epithelium consisting of 2 cell populations (cuboidal surface and polygonal stromal cells) and sharing some clinical characteristics (frequent occurrence in nonsmoking women of Asian ethnicity) with bronchioloalveolar carcinoma with which it has been suggested a possible common origin. We investigated 11 cases of SH by immunohistochemistry, fluorescence in situ hybridization, and polymerase chain reaction-based microsatellite and mutational analyses with particular emphasis on possible alterations of microsatellite loci located at tumor suppressor genes (FHIT, p16, Rb, and p53) involved in lung adenocarcinoma genesis and EGFR, HER2, and K-RAS genes. Although EGFR expression was observed in all tested cases, none showed HER2 immunostaining. Fluorescence in situ hybridization and mutational analysis of EGFR and HER2 and also K-RAS sequencing did not reveal molecular alterations, whereas allelic losses at p16 and Rb loci (4 and 2 out of 9 tested cases, respectively) with an identical microsatellite allelic loss pattern in both cuboidal and polygonal cells were observed. The finding of microsatellite alterations in chromosomal regions related to genes deeply involved in early stage lung adenocarcinoma could suggest a possible link between SH and bronchioloalveolar carcinoma, but tumor pathway promoted by EGFR, HER2, and K-RAS does not represent a common molecular mechanism of tumorigenesis. Microsatellite alterations identified in cuboidal and polygonal cells further confirm the clonal and neoplastic nature of both components of SH.

[Study of androgen receptor and phosphoglycerate kinase gene polymorphism in major cellular components of the so-called pulmonary sclerosing hemangioma].

OBJECTIVE: To study the clonality of polygonal cells and surface cuboidal cells in the so-called pulmonary sclerosing hemangioma (PSH). METHODS: 17 female surgically resected PSH were found. The polygonal cells and surface cuboidal cells of the 17 PSH cases were microdissected from routine hematoxylin and eosin-stained sections. Genomic DNA was extracted, pretreated through incubation with methylation-sensitive restrictive endonuclease HhaI or HpaII, and amplified by nested polymerase chain reaction for X chromosome-linked androgen receptor (AR) and phosphoglycerate kinase (PGK) genes. The length polymorphism of AR gene was demonstrated by denaturing polyacrylamide gel electrophoresis and silver staining. The PGK gene products were treated with Bst XI and resolved on agarose gel. RESULTS: Amongst the 17 female cases of PSH, 15 samples were successfully amplified for AR and PGK genes. The rates of polymorphism were 53% (8/15) and 27% (4/15) for AR and PGK genes respectively. Polygonal cells and surface cuboidal cells of 10 cases which were suitable for clonality study, showed the same loss of alleles (clonality ratio = 0) or unbalanced methylation pattern (clonality ratio < 0.25). CONCLUSIONS: The polygonal cells and surface cuboidal cells in PSH demonstrate patterns of monoclonal proliferation, indicating that both represent true neoplastic cells.

Expression of the estrogen receptor beta in 37 surgically treated pulmonary sclerosing hemangiomas in comparison with non-small cell lung carcinomas.

Sclerosing hemangioma (SH) of the lung is an uncommon tumor with a predilection for middle-aged women. This special phenomenon prompted us to examine SH for the expression of ERalpha (human estrogen receptor) and ERbeta (a second isoform of estrogen receptor). To investigate the staining pattern of these tumors, we also stained lung tissues from patients with non-small cell lung carcinomas and nonneoplastic type II pneumocytes for comparison. Thirty-seven pulmonary SHs and 301 non-small cell lung cancers specimens were explored. Expression of ERalpha and ERbeta was immunohistochemically measured. The overall frequency of overexpression for ERbeta was 91.9%. It was detected in both female (in 91.4% of 35 cases) and male (in 100.0% of 2 tumors from men) patients. There was ERbeta overexpression in all 9 tumors of solid pattern, 6 of 7 tumors of papillary pattern, all 4 tumors of sclerotic pattern, 12 of 13 tumors of hemorrhagic pattern, and 3 of 4 tumors of mixed pattern. The staining pattern of the neoplastic cells of the SH was similar to that of type II pneumocytes adjacent to the tumor rather than that of non-small cell lung cancers, in which the frequency of ERbeta overexpression was 45.8%. However, there was no ERalpha detectable in these neoplasms. Estrogen receptor beta overexpression is very frequent in pulmonary SHs, which is similar to that of alveolar cells but quite different from non-small cell carcinoma.