Bilateral multiple sclerosing hemangiomas of the lung

Multiple Pulmonary Sclerosing Pneumocytomas (PSPs): A Comprehensive Analysis of Clinicopathological Characteristics and Whole-exome Sequencing (WES) Results

Pulmonary sclerosing pneumocytoma (PSP) is a rare neoplasm with indolent clinical behavior and usually presents as a solitary nodule, while only a few cases involving multiple nodules. Recent studies have revealed frequent AKT1 mutations in PSP; however, the molecular genetics of multiple PSPs remain unclear. To better understand the genetic background, eleven patients (4.2%, 11/260) with multiple PSP nodules were identified, and whole-exome sequencing (WES) was performed on 6 patients. Among 5 patients with 2 or 3 PSP nodules, AKT1 alterations were the most common (50%, 7/14), and the predominant alteration was p.E17K (21.4%, 3/14). Novel ARID1A mutations were the second most common driver (14.3%, 2/14), and we first identified these mutations cooccurred with AKT1 p.E17K mutation. Moreover, we observed limited concordance in the mutation spectra and few comutated genes among different lesions from these 5 patients, indicating that PSP with 2 or 3 nodules were independent arising tumors. No AKT1 mutations were identified in 3 PSP samples from a patient with multiple diffuse nodules. However, there were 17 shared genetic alterations among the 3 lesions, but none were typical driver mutations. The findings on multiple diffuse PSP nodules may also have independent origins, but the potential that some of these nodules are metastatic nodules cannot be excluded. In conclusion, this retrospective study is the largest series of multiple PSP cases and provides new insights into the genomic underpinning of PSP. This work has a potential to broaden our understanding of the pathogenesis and development of these lesions and warrants analysis in larger cohorts.

Multiple pulmonary sclerosing pneumocytoma, based on a study of 36 cases worldwide

To analyze the clinical characteristics and to improve clinicians' understanding of multiple pulmonary sclerosing pneumocytoma (PSP) patients. A total of 36 PSP patients with multiple tumor characteristics were identified from the literature search. They were compared with 43 solitary PSP patients diagnosed and treated in our hospital in the past 5 years. Thus, the pathogenesis, clinical symptoms, diagnosis methods, treatment strategies, and prognosis of pulmonary sclerosing pneumocytoma (PSP) patients with multiple tumors were explored. Patients with multiple PSP are mostly distributed in Asia (88.89%) and are females (83.33%). PSP can be located in any one lobe (19.44%), or grow across ipsilateral lobes (44.44%), or even, bilateral lobes (36.11%). It can be accompanied by metastasis (9.09%) and is prone to misdiagnosis (27.78%). Compared with solitary PSP, the occurrence age of multiple PSP was younger (mean ± standard deviation [SD]: 40.36 ± 18.12: 51.28 ± 12.74 years), but there was no significant difference in sex, tumor size (mean ± SD: 43.54 ± 46.18: 30.56 ± 17.62 mm), or symptoms. Individualized surgical resection is required for treatment, including pneumonectomy (17.65%), lobectomy (23.53%), subpulmonary lobectomy (38.24%), or combined lobectomy (5.88%). Multiple PSP is relatively rare. Surgical resection within a limited time should be the main treatment for such patients. The prognosis of patients with multiple PSP is generally good, but inappropriate diagnosis and treatment plans may lead to poor prognosis.

Pulmonary sclerosing pneumocytoma: clinical features and prognosis

BACKGROUND

Pulmonary sclerosing pneumocytoma is a kind of rare benign pulmonary tumor with potential malignancy. The clinical features, risk factors for prognosis, and optimal treatment have not been identified yet. This study aimed to investigate the clinical features and prognosis of pulmonary sclerosing pneumocytoma.

METHODS

We retrospectively performed a review of pulmonary sclerosing pneumocytoma patients in West China Hospital from 2009 to 2019. The basic characteristics, treatment regimens, operation detail, postoperative variables, and follow-up time were recorded for each case. Differences in features between patients undergoing lobectomy and segmentectomy were compared. We also performed a case review and summarized reported clinical features in former studies.

RESULTS

Altogether 61 pulmonary sclerosing pneumocytoma patients were retrospectively reviewed. Fifty-six patients were female and 5 were male. The patients' median age was 51 (23-73). Seven (11.48%) patients had smoking history. Twenty tumors were located in the right lung [upper lobe (n = 7), middle (n = 2), and lower (n = 11)] and 41 in the left [upper (n = 12) and lower (n = 29)]. The median tumor size was 2 (0.9-7) cm. Thirty-six (59.02%) patients underwent sublobectomy (segmentectomy or wedge resection) whereas 25 (40.98%) underwent lobectomy. All patients recovered uneventfully, and no perioperative mortality was identified. Sublobectomy showed a trend towards reduced chest tube duration and shorter postoperative hospital stays compared with lobectomy.

CONCLUSIONS

The findings showed good prognosis of pulmonary sclerosing pneumocytoma and proved its benign characteristics. Sublobectomy showed advanced efficacy regarding chest tube duration and postoperative hospital stay compared with lobectomy.

Pulmonary Sclerosing Pneumocytoma: An Essential Differential Diagnosis for a Lung Nodule

Pulmonary sclerosing pneumocytoma, previously known as pulmonary sclerosing hemangioma, is a rare benign lung tumor with a low prevalence. We present this condition in a 26-year-old, young, non-smoking female with a slow-growing pulmonary nodule incidentally noted on imaging. Serial computed tomography(CT) scans revealed slow growth, and invasive testing was recommended. The patient underwent a left lateral thoracotomy and based on frozen section findings. A left lower lobectomy was performed. The final pathological diagnosis revealed sclerosing pneumocytoma. This is an atypical patient demographic considering the propensity of the disease for middle-aged Asian women. The case presentation and work-up highlight this critical differential diagnosis for incidental pulmonary nodules increasingly being noted due to widespread use of imaging for screening and routine care in the current medical climate. There are no specific imaging criteria to diagnose this condition. The final diagnosis is made only after surgical biopsy and histopathology. No additional treatment is needed following the diagnosis.

Benign tumours of the bronchopulmonary system

The vast majority of tumours arising in the bronchopulmonary system are malignant in nature. Benign tumours of the lung are relatively rare and are often incidental findings during clinical investigations for unrelated conditions. These lesions can arise in the bronchial tree or the pulmonary parenchyma and may be of epithelial, mesenchymal, salivary gland-type or unknown differentiation. Although the spectrum of these lesions is wide, the clinical, pathological and immunohistochemical characteristics of the most relevant will be the subject of this review. In addition, the most important features allowing differentiation from malignant pulmonary neoplasms will be discussed.

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.

Pulmonary sclerosing pneumocytoma in an 18-year-old male patient: A case report and literature review

RATIONALE

Pulmonary sclerosing pneumocytoma (PSP) is a rare benign tumor of the lung, mostly presented in Asian middle-aged women. Initially, it was considered as a vascular origin tumor, but then research evidence showed that it was derived from natural epithelial tissue. On imaging, this tumor may be found as a solitary well-circumscribed lung parenchymal lesion, and is often located in juxtapleural or juxtafissural positions. On histopathology, it consists of cuboidal surface cells and stromal round cells, both of which are positive for thyroid transcription factor-1. Here we report a case of a young PSP male patient and review the relevant literature in order to improve our understanding of this disease.

PATIENT CONCERNS

An 18-year-old man was referred to our hospital after accidentally finding a lesion on chest X-ray. Contrast-enhanced computed tomography showed a soft tissue mass with homogeneous enhancement in the left lower lobe posterior segment.

DIAGNOSES

The diagnosis of PSPs was confirmed by histopathological examination.

INTERVENTIONS AND OUTCOMES

The patient underwent a thoracoscopic wedge resection and was followed-up after that. One month later, he had good performance status with no recurrent tumors.

LESSONS

PSP in a young man is really uncommon, and is confused with malignant tumors. A histopathological examination is considered as the diagnostic gold standard for this uncommon tumor. Surgery is the main treatment.

Multiple sclerosing pneumocytomas: a review

Sclerosing pneumocytoma (SP) is a rare benign low-grade tumour of the lung, and typically presents as single discrete coin lesions on imaging. Multiple SP is an exceedingly rare entity and thus reported sparingly. We review the literature on multiple SP, their clinical presentations, histopathology, relevant differential diagnoses and molecular histogenesis of this entity. SP has a predilection for East Asian origin females who have never smoked. Patients are either asymptomatic or have symptoms such as cough, haemoptysis that may be persistent, chest pain if involving the pleura and presents as discrete coin lesion on chest X-ray. Histologically, they are papillary, solid, angiomatoid or sclerotic, or combinations of these four basic patterns. Multiple lesions have the same or slightly different histological patterns. They can be distributed in either lung, in any lobe and can even be bilateral. AKT-1 molecular pathways are pivotal in their molecular pathogenesis. In this review, we further propose a classification based on five types of distribution of multiple SP.

Pulmonary sclerosing pneumocytoma: Cytomorphology and immunoprofile

BACKGROUND

Sclerosing pneumocytoma (SP) is a rare, benign pulmonary neoplasm. To the authors' knowledge, the current study is the first to evaluate the cytomorphology and immunoprofile of SP in a series.

METHODS

A total of 9 fine-needle aspiration cases of SP (7 of which were computed tomography guided and 2 of which were endobronchial ultrasound guided) including histopathology and immunohistochemistry were collected from 5 institutions.

RESULTS

The female-to-male ratio was 3.5:1, and the mean age of the patients was 54 years (range, 27-73 years). All cases presented as lung nodules, with a mean size of 2.2 cm (range, 1.1-5 cm), and were interpreted as atypical on rapid on-site evaluation. The final diagnoses were favor adenocarcinoma (1 case), well-differentiated lung adenocarcinoma (2 cases), low-grade epithelial neoplasm (2 cases), and sclerosing pneumocytoma (4 cases). Samples were moderately cellular, and consisted of round epithelioid cells with clear cell features, columnar cells, and spindle cells. A papillary arrangement with prominent hyalinized fibrovascular cores was the most common architectural pattern, followed by flat sheets and acinar formations. Tumor cells demonstrated mild, focally moderate nuclear pleomorphism with prominent nucleoli, hyperchromasia, nuclear elongation, nuclear overlap, and occasional nuclear inclusions and grooves. The background consisted of foamy macrophages (9 cases), hemosiderin pigment (6 cases), and lymphoid aggregates (3 cases) with no mitoses and/or necrosis. The surface cells and underlying round cells were positive for both thyroid transcription factor 1 and epithelial membrane antigen in all cases, which was the most notable immunohistochemical finding.

CONCLUSIONS

Cytomorphological findings of SP overlap with those of well-differentiated lung adenocarcinoma. Awareness of these cytomorphologic findings and the distinct immunoprofile of the 2 cell types found in SP should prevent a misdiagnosis and aggressive treatment.

Sclerosing Pneumocytoma: A Ten-Year Experience at a Western Balkan University Hospital

Background and objective: Sclerosing pneumocytoma is a rare, benign tumor of the lung that represents a diagnostic challenge due to the diversity of pathohistological findings. The aim of this study was to present a 10-year experience with sclerosing pneumocytoma of a large center for the diagnosis and treatment of pulmonary diseases, and to emphasize differential diagnostic dilemmas as a potential source of errors. Material and Methods: This represents a retrospective study of six patients diagnosed and treated with sclerosing pneumocytoma in the 10-year period. The study analyzed various parameters, which are: Sex, age, symptoms, size and localization of the tumor, and its gross and histological features. Results: Sclerosing pneumocytoma was more frequently diagnosed in females (83.34%). The patients ranged in age from 38 to 61. Most of the patients (66.66%) were asymptomatic. Two patients underwent a video-assisted thoracoscopic surgery, two patients had a video-assisted minithoracotomy, and two patients underwent a thoracotomy in order to remove the tumor. The tumor was localized in the left lower lobe, in the right upper lobe, and in the right lower lobe in 50%, 33.34%, and 16.66% of patients, respectively. The tumor size ranged from 1 to 2.5 cm. A pathohistological examination of all six cases reported that all four major histological patterns were found in tissue sections: solid, papillary, sclerosing, and hemorrhagic. In all six cases, an immunohistochemical analysis showed positive expression of TTF-1 and panCK in surface epithelial cells, and TTF-1 positivity and panCK negativity in round stromal cells. Conclusions: Sclerosing pneumocytoma is a strictly histological diagnosis supported by clinical and radiological findings and corresponding immunohistochemical methods. Lung pathologists should always keep this tumor in mind, since its spectrum of differential diagnosis is wide, and therefore it can be an important diagnostic pitfall.

18F-FDG PET/CT characteristics of pulmonary sclerosing hemangioma vs. pulmonary hamartoma

The radiological features of pulmonary sclerosing hemangioma (PSH) and pulmonary hamartoma are poorly specified. Thus, the present study aimed to compare and analyze the characteristics of fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in PSH versus pulmonary hamartoma. ¹⁸F-FDG PET/CT characteristic findings of 12 patients with PSH and 14 patients with pulmonary hamartoma were retrospectively reviewed. A total of 12 lesions were detected from the 12 patients with PSH, of which 3 masses exhibited calcification. The mean diameter and standardized maximum uptake value (SUVmax) were 1.9±0.7 cm and 2.6±1.0, respectively, and there was no significant correlation between the lesion size and SUVmax (P>0.05). For the 14 patients with pulmonary hamartoma, 14 lesions were found, of which 4 exhibited calcification. The mean diameter and SUVmax were 1.7±0.8 cm and 1.5±0.6, respectively, and there was a significant correlation between the size and SUVmax (r=0.625, r²=0.391, P<0.05). Although there was no significant difference between the size of PSH and pulmonary hamartoma (P>0.05), the SUVmax of PSH was significantly higher than that of pulmonary hamartoma (P<0.05). Moreover, the SUVmax of 1.95 was applied as a cutoff for the diagnosis of PSH, and the resulting sensitivity and specificity for PET/CT to differentiate PSH from pulmonary hamartoma were 83.3 and 78.6%, respectively. Although the morphological features were not specific, PSH showed significantly higher FDG accumulation than pulmonary hamartoma on PET/CT imaging, which may aid the differential diagnosis. Further studies with larger populations are warranted to confirm these study results.

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.

A mixture of carcinoid tumors, extensive neuroendocrine proliferation, and multiple pulmonary sclerosing hemangiomas

We encountered an extremely rare case of multiple pulmonary sclerosing hemangiomas (PSH) with extensive neuroendocrine lesions, including pulmonary neuroendocrine cell (PNC) hyperplasia, multiple carcinoid tumorlets and typical carcinoid tumors within one pulmonary lobe. To the best of our knowledge, this is the first reported case in the English medical literature of PSH combined and admixed with carcinoid tumors and extensive neuroendocrine proliferation. This case is noteworthy for several reasons. First, the lesion is multi-nodular and unusually large for a typical PSH, which may mimic malignancy on imaging studies and cause diagnostic difficulties. Second, sampling bias may lead to diagnostic errors for a lesion containing two different types of neoplasms. Third, our case displays a rare mixed and mosaic pattern of PSH with a full spectrum of pulmonary neuroendocrine lesions, which may imply a potential intrinsic association in pathogenesis between PSH and concomitant neuroendocrine neoplasms. The clinical implication of multiple PSHs is also discussed.

Pulmonary sclerosing hemangioma with lymph node metastasis: A case report and literature review

Pulmonary sclerosing hemangioma (SH) is an uncommon benign or low-grade malignant tumor. Multicentric SH and SH with lymph node metastasis have rarely been reported. The present report describes a case of pulmonary SH with lymph node metastasis in a middle-aged female. A nodule was found incidentally in the lower left lung. The patient underwent left lower pulmonary lobectomy and lymph node dissection. Histologically, the nodule demonstrated the characteristic features of SH and one of the resected lymph nodes contained a metastasis of this tumor. Thus, pulmonary SH has the potential to metastasize, a potential not suggested by histological features.

Multiple peripheral typical carcinoid tumors of the lung: associated with sclerosing hemangiomas

Abstract

This study presents a first case of multiple peripheral typical carcinoid tumors associated with sclerosing hemangiomas in the lung. A 52-year-old male presented with incidentally detected multiple pulmonary nodules on a simple chest X-ray during routine health check-up. A computed tomography (CT) scan of the chest showed multiple nodular lesions in the middle and lower lobes of the right lung. These were initially suspected as inflammatory lesions due to miliary tuberculosis. However, possibility of malignancy could not be excluded and right lower lobe lobectomy was performed. Histopathologically, some nodules including two largest nodules were composed of small round to spindle shaped cells with fine chromatin pattern, whereas the rest of the sclerotic nodules were composed of two epithelial cell types- surface cells and round cells. The final diagnosis of this case was multiple peripheral typical carcinoid tumors associated with sclerosing hemangiomas of the lung. For past three years of post-surgery follow up period, no new lesions or changes in the right middle lobe have been identified.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1511610609725790.

Pulmonary sclerosing hemangioma: a unique epithelial neoplasm of the lung (report of 26 cases)

BACKGROUND

Pulmonary sclerosing hemangioma (SH) is an uncommon tumor. The aim of this study was to identify the origin of pulmonary SH and summarize its clinicopathologic features.

METHODS

Data of 26 cases of pulmonary SH were collected and reviewed, including their clinical symptoms, chest radiological examinations, treatments, and pathological findings.

RESULTS

Female patients of pulmonary SH were markedly frequent (n=23, 88.46%). Solitary mass or nodule in the lung fields was the most common manifestation (n=24, 92.31%), especially in the right middle lobe (n=9, 34.62%). There were two kinds of tumor cells: lining cells and round cells. All tumors contained a mixture of papillary, solid, sclerotic, and hemorrhagic patterns. Immunohistochemistry with a variable number of antibodies was performed for some cases. All of the detected specimens revealed strong reaction of lining cells with epithelial markers, such as thyroid transcription factor-1 (TTF-1), epithelial membrane antigen (EMA), cytokeratin (CK), pancytokeratin (PCK), and cytokeratin 7 (CK-7), while round cells were positive with TTF-1 and EMA. Until the end of last contact, none of the patients died or suffered from the recurrence of the disease after surgical treatment.

CONCLUSIONS

Pulmonary SH is a unique neoplasm of the lung with a characteristic solitary mass or nodule. Pulmonary epithelium might be the primary origin of the tumor cells.

Usefulness of Ki-67 (MIB-1) immunostaining in the diagnosis of pulmonary sclerosing hemangiomas

Pulmonary sclerosing hemangioma (PSH) is an uncommon lung neoplasm with a clinical outcome that is generally benign. However, differentiating PSH from pulmonary carcinoma is sometimes difficult as both lesions share similar histopathologic and immunohistochemical features. In this study, we investigated the usefulness of Ki-67 (MIB-1) immunostaining in the diagnosis of PSH. We compared the staining pattern for Ki-67 (MIB-1) in 29 cases of typical PSH and 79 cases of pulmonary non-small cell carcinoma (NSCLC) using an immunohistochemical method on formalin-fixed paraffin-embedded tissues. In all studied PSH cases, we noted cell membrane and cytoplasmic staining for Ki-67 (MIB-1), but this was not observed in any of the NSCLC cases. The Ki-67 proliferation index was lower in PSH than in the NSCLC cases (mean, 1.1% vs mean, 5.5%; p < 0.001). These findings suggest that cell membrane and cytoplasmic staining for Ki-67 (MIB-1), as well as the Ki-67 proliferation index, may be useful for distinguishing PSH from pulmonary carcinoma.

Treatment of 28 patients with sclerosing hemangioma (SH) of the lung

Background

Sclerosing hemangioma (SH) of the lung is a kind of rare pulmonary tumor. Preoperative diagnosis of this tumor is difficult and it is now generally accepted that SH of the lung is benign lesions and surgical excision alone is curative. Herein, we present our experiences of treating 28 patients with SH.

Methods

The medical records of 28 patients with SH from 1994 to 2010 at the Department of Thoracic Surgery in Beijing Chest Hospital were retrospectively reviewed.

Results

There were 3 male and 25 female patients with sclerosing hemangioma and 50% of the patients were asymptomatic. Preoperatively, all the patients had undergone CT of chest and 5 patients had undergone PET scan but 4 patients were misdiagnosed as malignancy. There was no operative mortality or tumor recurrence despite that three different operative methods were undertaken.

Conclusions

SH has a high incidence in middle-aged women. Most of SH is asymptomatic and the symptoms of SH are not related to the tumor size and distribution. The features of chest CT and PET are not specific. Bilateral or multiple lesions should not exclude the possibility of SH. Complete excision of lesion is a curable treatment method and there is no evidence to verify the need of adjuvant therapy.

Pulmonary sclerosing hemangioma: pitfalls in management

Pulmonary sclerosing hemangioma is a rare benign tumor for which surgical excision is curative with an excellent prognosis. It often mimics malignancy, making it a diagnostic and management challenge. We reviewed the clinical, radiological, and histopathological characteristics as well as the surgical management of our patients to assess the potential pitfalls in management. All 19 patients who underwent surgical biopsy between January 1999 and December 2009 with a final histopathological diagnosis of pulmonary sclerosing hemangioma were reviewed retrospectively. The median age was 48 years, 89.5% were female, 89.5% were Chinese, and 68.4% were asymptomatic. There were no specific diagnostic radiological characteristics; 1 of 3 patients who underwent combined positron-emission and computed tomography had a false-positive result. Preoperative attempts at establishing a diagnosis were successful in 20% of patients who had invasive procedures. Intraoperative frozen-section evaluation for pulmonary sclerosing hemangioma had an error rate of 25% and a deferred rate of 31%, resulting in nearly half of our patients undergoing unnecessary extensive surgical procedures. We hope to heighten awareness of this diagnosis, thereby increasing the index of suspicion and minimizing errors in diagnosis.