Epithelioid Vascular Tumors Research Articles

Molecular Testing Prevents Overdiagnosis of Epithelioid Hemangioma

Abstract Introduction/Objective Epithelioid hemangiomas (EH) are mostly solitary benign vascular tumors commonly involving the dermal and subcutaneous areas of the head and neck. However, reports of multifocality are increasing, specially in same anatomic region. Some reported cases of EH show morphologic features that may mimic malignant vascular tumors such as hemangioendotheliomas or angiosarcomas. However, there are no reported overlaps in the molecular characteristics of these tumors. We describe a multifocal EH with atypical features, suspicious for angiosarcoma, which needed molecular testing to resolve the diagnosis. Methods/Case Report The patient is a previously healthy 42-year-old male with a 5-month history of multiple growing painless penile nodules. Biopsy of one of the nodules was done. Histologic examination showed multifocal dermal- based ill-circumscribed nodules with interspersed inflammatory infiltrates and focal areas of necrosis. Tumor periphery shows vasoformative growth with intraluminal and extravasated red blood cells. Neoplastic cells were large and ovoid with abundant eosinophilic cytoplasm, large vesicular pleomorphic nuclei and prominent nucleoli. Immunohistochemical stains showed strong expression of ERG, FLI-1, and CD31 and negativity for AE1/AE3, CD34, HHV8 and EMA. The morphologic and immunohistochemical features of the specimen showed significant overlap of two primary differential diagnoses - epithelioid angiosarcoma and epithelioid hemangioma. Ultimately, molecular testing revealed ZFP36-FOSB fusion, confirming the diagnosis of EH. Results (if a Case Study enter NA) NA Conclusion Differentiating benign and malignant epithelioid vascular neoplasms can sometimes be challenging. There can be overlap in terms of architectural variety, presence of necrosis, vasoformation, inflammatory cell components and cytologic features, especially in EH with atypical features and epithelioid angiosarcoma (EA). Both of these tumors show positive immunoreactivity for CD31, CD34, FLI1 and ERG, and negativity for most keratins. Currently, the most reliable way to distinguish each tumor is molecular testing, with EH having FOS/FOSB rearrangements and EA with MYC or FLT4 amplification. Benign and malignant epithelioid vascular tumors can be indistinguishable morphologically and immunohistochemically. Molecular tests can help differentiate these neoplasms to better tailor patient management.

Epithelioid Hemangioma of the Spine: A Case Series and Treatment Flow Chart-Experience from a Single Centre.

Epithelioid hemangioma is recognized by the World Health Organization as a distinct benign neoplasm; however, it is characterized by locally aggressive and rarely metastasizing behavior. Epithelioid vascular tumors are rare bony vascular lesions with varying degrees of malignant potential that remain controversial because of their rarity, unusual morphological features, and unpredictable biological behavior. The application of new molecular tools, such as massive parallel sequencing technologies, have provided new diagnostic markers and an opportunity to further refine the classification of bone vascular neoplasms. Very few cases of EH of the spine have been reported in the literature; therefore, it is difficult to make evidence-based therapeutic decisions for these patients. We report herein our experience with eleven patients suffering from EH of the spine. The study population included three males and eight females treated in our center from 2016 to the present; the average age was 44.8 years (range 14-75 years). The surgical, clinical, and radiographic data were retrospectively analyzed. The mean follow-up was 34.8 months. All patients presented lytic vertebral body lesions, six of them with pathological fracture. The majority of patients (80%) presented myelo-radicular compression. All patients were surgically treated, and preoperative embolization was performed in all cases. In light of the literature review and the clinical experience of our center, we can consider EH a locally aggressive tumor that requires surgical treatment in case of symptoms. Here, we propose a treatment algorithm that could be useful in the management of patients with this rare disease.

SOFT TISSUE EPITHELIOID VASCULAR TUMORS: A PRACTICAL CLINICO PATHOLOGICAL DIAGNOSTIC APPROACH

Soft tissue epithelioid vascular tumors are characterized by a wide spectrum and represent a controversial topic for overlapping morphologic features; they require depth knowledge of the various subtypes, in order to be able to predict the clinical behaviour of the lesion. The World Health Organization (WHO) classification of soft tissue tumours recognizes multiple vascular … Continued

Loss of expression of YAP1 C-terminus as an ancillary marker for epithelioid hemangioendothelioma variant with YAP1-TFE3 fusion and other YAP1-related vascular neoplasms

Epithelioid hemangioendothelioma (EHE) with YAP1-TFE3 fusion is a recently characterized distinctive variant of EHE that accounts for a small subset (<5%) of cases. It is composed of nests of epithelioid cells with voluminous pale cytoplasm and often shows focally vasoformative architecture. TFE3 immunohistochemistry (IHC) can be used to support the diagnosis; however, studies have questioned its specificity. Yes-associated protein 1 (YAP1), part of the Hippo signaling pathway, is expressed in normal endothelial cells, but becomes disrupted in EHE variant with YAP1-TFE3, such that only a small N-terminal region of YAP1 is expressed in the fusion protein. A recent study also reported YAP1 rearrangements in a subset of retiform and composite hemangioendotheliomas (RHE and CHE). In this study, we evaluated the diagnostic utility of an antibody directed against the C-terminus of YAP1 (YAP1-CT) for EHE with YAP1-TFE3, RHE, and CHE. In total, 78 tumors were included in the study: EHE variant with YAP1-TFE3 (n = 13), conventional (CAMTA1-positive) EHE (n = 20), pseudomyogenic hemangioendothelioma (n = 10), epithelioid hemangioma (n = 19), epithelioid angiosarcoma (n = 10), RHE (n = 4), and CHE (n = 2). IHC was performed using a rabbit monoclonal anti-YAP1 C-terminus antibody. EHE variant showed complete loss of YAP1-CT expression in 10 of 13 (77%) cases. All cases of RHE and CHE, with previously confirmed YAP1 rearrangements, also showed loss of YAP1-CT expression. Loss of YAP1-CT was seen in one conventional EHE (1/20; 5%). All other epithelioid vascular tumors showed retained YAP1-CT expression. Loss of expression of YAP1-CT appears to be associated with good sensitivity and specificity for EHE variant with YAP1-TFE3 fusion and may provide additional support along with TFE3 and CAMTA1 IHC in challenging cases. This marker may also be useful in the diagnosis of RHE and CHE.

A unique epithelioid vascular neoplasm of bone characterized by EWSR1/FUS-NFATC1/2 fusions.

An increasing number of epithelioid vascular lesions, in particular tumors from the benign and low-grade end of the spectrum, have been characterized by recurrent gene fusions. As a result, the detection of these molecular markers have improved the classification of diagnostically challenging cases. However, despite the significant progress, there are occasional lesions that do not fit in known histologic or molecular groups. Herein, we present five such unclassified epithelioid vascular lesions, which occurred in the bone and showed a distinct morphology composed of alternating vasoformative and solid growth and mild to moderate nuclear pleomorphism. The variegated morphologic appearance resembled that of composite hemangioendothelioma, being distinct from both epithelioid hemangioma and epithelioid hemangioendothelioma, and consistently showed cytologic atypia. Due to their unusual morphologic appearance and negative molecular work-up, targeted transcriptome sequencing was performed in two cases showing the presence of NFATC2 fusions with either EWSR1 or FUS genes. Three additional bone tumors with EWSR1 gene rearrangements were identified by FISH screening of a large cohort of 45 fusion-negative epithelioid vascular neoplasms, one fused to NFATC2 while two others to NFATC1. There were three females and two males, with a wide age range at presentation, mean of 44 years. The lesions occurred in the pelvis, maxillary sinus, and humerus. Two patients presented with polyostotic disease, both located in the pelvic bones. Two patients had available follow-up, one developed two local recurrences in the humerus over a 15-year period, while the other showed no recurrence 4 years subsequent to an en-bloc resection. Tumors were positive for CD31 and ERG, while negative for EMA, CK, synaptophysin, and chromogranin. FISH confirmed this abnormality in all cases, none of them being associated with gene amplifications. Further studies are needed to establish the pathogenetic relationship of this rare molecular subset with other epithelioid vascular tumors and to determine its clinical behavior.

Epithelioid hemangioma of bone harboring FOS and FOSB gene rearrangements: A clinicopathologic and molecular study.

The diagnosis of epithelioid hemangioma (EH) remains challenging due to its rarity, worrisome histologic features, and locally aggressive clinical and radiographic presentation. Especially in the bone, EH can be misdiagnosed as a malignant vascular neoplasm due its lytic, often destructive or multifocal growth, as well as atypical morphology. The discovery of recurrent FOS and FOSB gene fusions in the pathogenesis of most EH has strengthened its stand-alone classification, distinct from other malignant epithelioid vascular lesions, such as epithelioid hemangioendothelioma or angiosarcoma. In this study we investigate a group of molecularly confirmed skeletal EH by the presence of FOS or FOSB gene rearrangements to better define its clinical and pathologic characteristics within a homogenous molecular subset. The cohort included 38 patients (25 males, 13 females), with a mean age at diagnosis of 38 years (range, 4-75). Regional, multifocal presentation was noted in 10 cases. Only six cases were correctly recognized as EH by the referring institutions, while most were misdiagnosed as other vascular tumors. Of the 17 patients with follow-up data available, five patients (29%) developed local recurrence after marginal en bloc excision (n = 3) or curettage (n = 2). Local recurrence-free survival rates were 84% at 3 years and 38% at 5 years. No metastasis or disease-related death was identified. Imaging studies exhibited no specific features, showing cortical bone destruction and soft-tissue extension in 14 (38%) cases. FOS gene rearrangements were detected in 28 (74%) of cases, while FOSB rearrangements in 10 (26%) cases. Our results highlight the significant challenges encountered in establishing a correct diagnosis exclusive of the molecular testing, mainly due to its overlap to other malignant epithelioid vascular tumors. Skeletal EH emerges as a genetically defined locally aggressive vascular neoplasm, with a high rate of local recurrence, but lacking the propensity for distant spread.

Epithelioid Vascular Tumors: A Review.

Vascular tumors are a diagnostically challenging area. This is particularly true in the case of epithelioid vascular tumors. Not only is the distinction between different epithelioid vascular tumors challenging, but also the differential diagnosis may be substantially expanded by the inclusion of melanoma, carcinomas, and other epithelioid soft tissue tumors. Recently developed immunohistochemical markers and more comprehensive genetic characterizations continue to advance our understanding of epithelioid vascular tumors. The present paper briefly reviews and updates basic concepts with regard to the following epithelioid vascular tumors: epithelioid hemangioma, epithelioid angiomatous nodule, pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, epithelioid hemangioendothelioma, and epithelioid angiosarcoma.

Multiple Eruptive Epithelioid Hemangiomas: A Subset of Cutaneous Cellular Epithelioid Hemangioma With Expression of FOS-B.

There is a wide clinicopathologic spectrum of vascular proliferations characterized by the presence of epithelioid endothelial cells, comprising epithelioid hemangioma (EH)-pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma (PM-HAE), epithelioid hemangioendothelioma, and epithelioid angiosarcoma. Immunohistochemical FOS-B expression as well as FOS-B rearrangement (fluorescent in situ hybridization [FISH]) have recently been described as diagnostically relevant underpinnings of EH (restricted to osseous lesions) and PM-HAE. The aim of this study was to clinicopathologically characterize and to elucidate FOS-B expression in patients with eruptive lesions of the cellular variant of cutaneous EH. All cases of cutaneous cellular EH (n=16) showed strong diffuse immunohistochemical expression of FOS-B, in conjunction with positivity for ERG and nestin. Expression of MYC, CAMTA-1, AE1/3, and MNF116 was negative in all cases. FISH investigations did not show any sign of rearrangements for CAMTA-1 or MYC amplification. Negative-control cases included 15 lobular hemangiomas, 5 epithelioid angiosarcomas, and 5 nodular Kaposi sarcomas, all of which were negative for FOS-B. Positive-control cases included 15 angiolymphoid hyperplasia with eosinophilia cases, all of them being positive. In contrast with what has been published so far, cutaneous variants of cellular EH exhibit positive immunostaining for FOS-B. Remarkably, FOS-B expression is not restricted to the intraosseous subset of EH. For differential diagnosis of epithelioid vascular tumors, we therefore suggest a helpful panel of antibodies including CAMTA-1, TFE-3, FOS-B, and AE1/AE3. We point out the telltale immunophenotypes: angiolymphoid hyperplasia with eosinophilia and EH (FOS-B/others negative), PM-HAE (FOS-B/AE1/AE3/others negative), epithelioid hemangioendothelioma (CAMTA-1 or TFE-3/others negative). Remarkably, MYC is not expressed in these tumors, neither is there an MYC amplification by FISH. We suggest the term multiple eruptive EHs for this subset of cutaneous vascular tumors.

Prognostic Factors of Patients With Malignant Epithelioid Vascular Tumors in the Spine

A retrospective study of 46 patients with malignant epithelioid vascular tumors (MEVT) in the spine was performed. The purpose of this study was to illustrate the clinic characteristics of MEVT in the spine and to discuss prognostic factors by survival analysis. MEVT in the spine is relatively uncommon, and there is little published information regarding this subject. Therefore, prognostic factors of this disease are still controversial. The univariate and multivariate analysis of various clinic characteristics were performed to identify the independent factor that affects prognosis for patients with MEVT in the spine who underwent surgical treatment in Changzheng Hospital Orthopedics Oncological Center (CHOOC) between 2005 and 2015. Disease-free survival (DFS) and overall survival (OS) were estimated by Kaplan-Meier method to identify potential prognostic factors. Factors with P values of 0.1 or less were subjected to multivariate analysis by Cox regression analysis. P values of 0.05 or less was considered statistically significant. A total of 46 patients with MEVT in the spine were included in the study. The mean follow-up period was 42.6 months (range, 5-143 mo). Recurrence was detected in 22 patients after initial surgery in our center, whereas death in 18 patients. The univariate analysis suggested that age (<30 yr/≥30 yr), metastasis, preoperative Frankel score, postoperative Frankel score, malignant grade and resection mode were potential prognostic factors for DFS and OS. However, as they were submitted to multivariate analyses, only malignant grade and resection mode were independent prognostic factors. Total en bloc spondylectomy can significantly improve DFS for MEVT in the spine and low-grade malignancy was favorable factor for DFS. Total spondylectomy and low-grade malignancy considerably improve OS for patients with MEVT in the spine. 4.

FOSB immunoreactivity in endothelia of epithelioid hemangioma (angiolymphoid hyperplasia with eosinophilia).

Accurate distinction of epithelioid hemangioma (EH) from its malignant mimics is paramount but remains challenging due to its wide morphological spectrum and lack of objective molecular markers. FOSB oncogenic activation was recently identified as a key event in endothelial proliferation. We sought to investigate the FOSB staining pattern in EH with angiolymphoid hyperplasia with eosinophilia (EH-AHLE) morphology and to evaluate its value in differential diagnosis of epithelioid vascular tumors. From the authors' files, 15 representative cases of EH-ALHE were selected and evaluated for their FOSB immunostaining pattern. Other vascular proliferations which can be morphological mimics were also tested: epithelioid hemangioendothelioma (EHE) (5 cases) and epithelioid angiosarcoma (EAS) (5 cases). All 15 cases of EH-ALHE showed strong and homogeneous FOSB nuclear expression in endothelial cells with ample cytoplasm and intracytoplasmic vacuoles. All cases of EHE and EAS lacked FOSB immunoreactivity or showed only incidental weak FOSB immunoreactivity in less than 5 nuclei per lesion. FOSB immunohistochemistry is sensitive in the diagnosis of EH-ALHE, and allows differentiation from its histological mimics. An immunohistochemical panel including not only pan-cytokeratin AE1/AE3 and endothelial markers, but also FOSB, helps in the diagnosis of epithelioid vascular tumors.

Angiolymphoid hyperplasia with eosinophilia: report of nine cases.

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a benign vascular proliferation characterized by dermal or subcutaneous red or brown papules or nodules, most commonly on the head and neck. The aim of this study was to review the epidemiological and clinical characteristics of ALHE, focusing particularly on the histological and therapeutic features. We performed a retrospective study of all cases of ALHE diagnosed in our dermatology and pathology departments between 2004 and 2015. Over 12 years, we collected nine cases of ALHE (0.75 case/year). There were four men and five women. The mean age was 43 years. Lesions presented as erythematous or violaceous papules or nodules in all cases, multiple in five cases, and localized on the head in eight cases or other sites in four cases. The diagnosis of ALHE was clinically suspected in only two cases. The histopathological findings showed an ill-circumscribed, intradermal slightly lobular proliferation of capillary-sized vessels around several central vessels. In all cases, the blood vessels were lined by large endothelial cells. An inflammatory infiltrate around the vessels was formed mainly of lymphocytes and eosinophils with isolated plasma cells and histiocytes. Surgery was the most common treatment in our series. Other local or general treatment has also been used with varying responses. Angiolymphoid hyperplasia with eosinophilia is a rare epithelioid vascular tumor with a challenging clinical and histological diagnosis. Despite its benign nature, ALHE causes a therapeutic dilemma.

Frequent FOS Gene Rearrangements in Epithelioid Hemangioma

Epithelioid hemangioma (EH) is a unique benign vasoformative tumor composed of epithelioid endothelial cells. Although a small subset of EHs with atypical features harbor ZFP36-FOSB fusions, no additional genetic abnormalities have been found to date in the remaining cases. On the basis of a novel FOS-LMNA gene fusion identified by RNA sequencing in an index case of a skeletal EH with typical morphology, we sought to investigate the prevalence of FOS rearrangement in a large cohort of EHs. Thus 57 additional EH cases lacking FOSB rearrangements were studied for FOS gene abnormalities by fluorescence in situ hybridization, and results were correlated with morphologic appearance and clinical presentation. The EHs were subclassified as typical (n=25), cellular (n=21), and angiolymphoid hyperplasia with eosinophilia (ALHE) (n=12) variants. The ALHE was defined as an EH with a vascular "blow-out" pattern associated with a variable degree of inflammation. There were 17 (29%) cases bearing FOS gene rearrangements among 58 cases tested, including 12 male and 5 female patients, with a mean age of 42 years. Most FOS-rearranged EHs occurred in the bone (10) and soft tissue (6), whereas only 1 case was cutaneous. The predominant anatomic site was the extremity (12), followed by trunk (3), head and neck (1), and penis (1). The incidence of FOS rearrangement was significantly higher in bone (59%, P=0.006) and lower in head and neck (5%, P=0.009). Twelve of the FOS-rearranged cases were cellular EH (P=0.001) associated with moderate mitotic activity (2 to 5/10 HPF) and milder inflammatory background. All 12 ALHE cases lacked FOS gene abnormalities, suggesting different pathogenesis. In conclusion, FOS rearrangement was present in a third of EHs across different locations and histologic variants; however, it was more prevalent in cellular EH and intraosseous lesions, compared with those in skin, soft tissue, and head and neck. This genetic abnormality can be useful in challenging cases, to distinguish cellular EHs from malignant epithelioid vascular tumors. These results also suggest that dysregulation of the FOS family of transcription factors through chromosomal translocation is as a key event in the tumorigenesis of EH except for the ALHE variant.

Epithelioid Hemangioendothelioma of the Maxillary Sinus

The clinical course and pathologic features of a 72 year old female who presented with epistaxis are presented. Radiographic findings were notable for a large, soft tissue lesion filling the maxillary sinus with significant bony erosion and expansion. The patient was ultimately diagnosed with epithelioid hemangioendothelioma (EHE) and underwent endoscopic resection. She has no evidence of local, regional or distant recurrence 14 months post-surgery. The rarity of this neoplasm, the unusual anatomic location and non-specific symptoms present diagnostic and management challenges. Epithelioid vascular tumors encompass a spectrum of benign and malignant tumors. EHE itself is thought to have an intermediate malignant behavior pattern, though cases with indolent behavior have been reported. Differentiation of EHE from other lesions has historically based on histopathology. Additionally, recent studies have described a recurrent genetic fusion WWTR1-CAMTA1 in EHE, involving t(1;3) (p36;q25). This represents the second reported case of EHE arising in a paranasal sinus. The histopathologic findings of this lesion are reviewed.

Thoracic epithelioid malignant vascular tumors: a clinicopathologic study of 52 cases with emphasis on pathologic grading and molecular studies of WWTR1-CAMTA1 fusions.

Malignant thoracic epithelioid vascular tumors are an uncommon and heterogenous group of tumors that include low-grade to intermediate-grade epithelioid hemangioendothelioma (EHE) and high-grade epithelioid angiosarcoma (EAS). We examine the morphologic and immunohistochemical features of 52 malignant epithelioid vascular tumors (10 low-grade EHE, 29 intermediate-grade EHE, and 13 EAS) involving the thorax (lung, pleura, mediastinum, heart, great vessels) including cases with exclusively thoracic disease (35) and with multiorgan disease including the thorax (17). Intermediate-grade EHE differs from low-grade EHE by the presence of necrosis, increased mitotic activity, and increased atypia. Morphologic features such as intranuclear inclusions, intracytoplasmic vacuoles, and stromal changes (chondroid, myxoid, or hyalinized stroma) are seen more frequently in EHE, whereas blood lakes, proliferation of slit-like vessels, and prominent nucleoli favor EAS. Fluorescence in situ hybridization analysis showed CAMTA1-WWTR1 fusions in 4/7 low-grade and 23/23 intermediate-grade EHE (P<0.001). In EAS, CAMTA1 rearrangement was negative in all cases, whereas a WWTR1 complex abnormality was found in 1/5 cases (P<0.001). This offers an objective means of differentiating intermediate-grade EHE from EAS, especially on limited biopsies. All cases show expression of at least 1 vascular marker, which allows differentiation from primary thoracic epithelial malignancies, although keratin expression is a potential pitfall with 29% of EHE and 25% of EAS showing keratin expression. Survival analysis shows that higher tumor grade for all tumors (P=0.026) as well as lung and pleural tumors only (P=0.010) and the presence of pleural involvement in lung and/or pleural tumors (P=0.042) correlate with poor prognosis.

Malignant vascular tumors—an update

Although benign hemangiomas are among the most common diagnoses amid connective tissue tumors, sarcomas showing endothelial differentiation (ie, angiosarcoma and epithelioid hemangioendothelioma) represent under 1% of all sarcoma diagnoses, and thus it is likely that fewer than 500 people in the United States are affected each year. Differential diagnosis of malignant vascular tumors can be often quite challenging, either at the low end of the spectrum, distinguishing an epithelioid hemangioendothelioma from an epithelioid hemangioma, or at the high-grade end of the spectrum, between an angiosarcoma and a malignant epithelioid hemangioendothelioma. Within this differential diagnosis both clinico-radiological features (ie, size and multifocality) and immunohistochemical markers (ie, expression of endothelial markers) are often similar and cannot distinguish between benign and malignant vascular lesions. Molecular ancillary tests have long been needed for a more objective diagnosis and classification of malignant vascular tumors, particularly within the epithelioid phenotype. As significant advances have been recently made in understanding the genetic signatures of vascular tumors, this review will take the opportunity to provide a detailed update on these findings. Specifically, this article will focus on the following aspects: (1) pathological and molecular features of epithelioid hemangioendothelioma, including the more common WWTR1–CAMTA1 fusion, as well as the recently described YAP1–TFE3 fusion, identified in a morphological variant of epithelioid hemangioendothelioma; (2) discuss the heterogeneity of angiosarcoma clinical, morphological and genetic spectrum, with particular emphasis of MYC and FLT4 gene amplification in radiation-induced angiosarcoma; and (3) provide a practical guide in the differential diagnosis of epithelioid vascular tumors using molecular testing.

Clinical, radiologic, and pathologic analysis of penile epithelioid hemangioendothelioma: A diagnostic and management dilemma

Epithelioid hemangioendotheliomas (EHE) are rare soft tissue tumors and only 17 cases involving the penis have been reported in the literature. These tumors are often incorrectly diagnosed as Peyronie's disease or superficial penile thrombosis. We present the case of a 59-year-old male referred to our institution with EHE after being incorrectly diagnosed with Peyronie's disease. A color Doppler ultrasound of the penis showed a highly vascular mass superficial to the tunica albuginea and a subsequent biopsy demonstrated EHE with low-grade features. Complete local excision was performed and given the patient's low-risk pathological features, he has been followed with only close surveillance. Early recognition of epithelioid vascular tumors is important and using adequate imaging modalities is critical to avoid prolonged periods of misdiagnosis.

A case of multiple epithelioid angiomatous nodules

Cutaneous epithelioid angiomatous nodule (CEAN) is a distinct type of epithelioid vascular tumor that is usually solitary. Herein we present a 31-year-old man with multiple, rapidly growing nodules on the scalp.

Epithelioid Hemangioma of Bone and Soft Tissue: A Reappraisal of a Controversial Entity

The controversy surrounding diagnosis of an epithelioid hemangioma (EH), particularly when arising in skeletal locations, stems not only from its overlapping features with other malignant vascular neoplasms, but also from its somewhat aggressive clinical characteristics, including multifocal presentation and occasional lymph node involvement. Specifically, the distinction from epithelioid hemangioendothelioma (EHE) has been controversial. The recurrent t(1;3)(p36;q25) chromosomal translocation, resulting in WWTR1-CAMTA1 fusion, recently identified in EHE of various anatomic sites, but not in EH or other epithelioid vascular neoplasms, suggests distinct pathogeneses. We investigated the clinicopathologic and radiologic characteristics of bone and soft tissue EHs in patients treated at our institution with available tissue for molecular testing. Seventeen patients were selected after confirming the pathologic diagnosis and fluorescence in situ hybridization analysis for the WWTR1 and/or CAMTA1 rearrangements. Four patients had multifocal presentation. Most patients with EH of bone were treated by intralesional curettage. None of the patients died of disease and only four patients had a local recurrence. Our results, using molecular testing to support the pathologic diagnosis of EH, reinforce prior data that EH is a benign lesion characterized by an indolent clinical course with an occasional multifocal presentation and rare metastatic potential to locoregional lymph nodes. These findings highlight the importance of distinguishing EH from other malignant epithelioid vascular tumors as a result of differences in their management and clinical outcome. Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

A novel WWTR1-CAMTA1 gene fusion is a consistent abnormality in epithelioid hemangioendothelioma of different anatomic sites.

The classification of epithelioid vascular tumors remains challenging, as there is considerable morphological overlap between tumor subtypes, across the spectrum from benign to malignant categories. A t(1;3)(p36.3;q25) translocation was reported in two cases of epithelioid hemangioendothelioma (EHE), however, no follow-up studies have been performed to identify the gene fusion or to assess its prevalence in a larger cohort of patients. We undertook a systematic molecular analysis of 17 EHE, characterized by classic morphological and immunophenotypic features, from various anatomical locations and with different malignant potential. For comparison, we analyzed 13 epithelioid hemangiomas, five epithelioid angiosarcomas, and four epithelioid sarcoma-like EHE. A fluorescence in situ hybridization (FISH) positional cloning strategy, spanning the cytogenetically defined regions on chromosomes 1p36.3 and 3q25, confirmed rearrangements in two candidate genes from these loci in all EHE cases tested. None of the other benign or malignant epithelioid vascular tumors examined demonstrated these abnormalities. Subsequent reverse transcription-polymerase chain reaction (RT-PCR) confirmed in three EHE the WWTR1-CAMTA1 fusion product. CAMTA1 and WWTR1 have been previously shown to play important roles in oncogenesis. Our results demonstrate the presence of a WWTR1-CAMTA1 fusion in all EHE tested from bone, soft tissue, and visceral location (liver, lung) in keeping with a unique and specific pathological entity. Thus, FISH or RT-PCR analysis for the presence of WWTR1-CAMTA1 fusion may serve as a useful molecular diagnostic tool in challenging diagnoses.

Unclassified epithelioid vascular tumor with hemangioendotheliomatous features and lymphatic differentiation

Reported herein is an unusual vascular tumor that arose in the little finger of a 10-year-old boy. The tumor consisted of a vaguely demarcated nodular mass, which was located in the subcutaneous layer and measured 1 cm in diameter. Microscopic characteristic findings of this tumor were epithelioid nests, admixed with focal components with retiform features, intraluminal papillary tufts, and spindle cells. These features resemble those of subtypes of hemangioendotheliomas. On immunohistochemistry CD31, CD34 and D2-40 were diffusely expressed in the tumor cells, representing prominent lymphatic differentiation. These findings are not characteristic of any established types of vascular tumors. The differential diagnosis for the current peculiar tumor are discussed.