Hepatic small vessel neoplasm, a rare infiltrative vascular neoplasm of uncertain malignant potential

Diagnostic approach to hepatic vascular lesions: a paediatric perspective

The pathological evaluation of hepatic vascular lesions in children requires special consideration. Inconsistent terminology, rarity of pathology specimens and overlapping pathological features between various lesions may pose a serious diagnostic challenge. In this review, we highlight the importance of using the International Society for the Study of Vascular Anomalies (ISSVA) classification scheme to characterise these lesions. Selected entities are discussed, including hepatic vascular tumours exclusively seen in the paediatric age group, hepatic infantile haemangioma and hepatic congenital haemangioma. Vascular malformations, with emphasis on their syndromic associations (venous malformation in blue rubber bleb naevus syndrome) and complications (hepatocellular nodules in Abernethy malformation) are also covered.

GNAQ/GNA11-Related Benign and Malignant Entities-A Common Histoembriologic Origin or a Tissue-Dependent Coincidence

Uveal melanoma (UM), recognized as the most prevalent primary intraocular malignancy in adults, is primarily driven by mutations in the GNAQ and GNA11 genes. These genetic alterations are also implicated in other conditions, which exhibit distinct morphological characteristics. In this article, we investigate the role of GNAQ and GNA11 mutations across varied disorders (e.g., UM, skin blue nevi, and hemangiomas), emphasizing the shared pathogenic mechanisms that connect them despite their differing clinical manifestations. By investigating the molecular pathways affected by these mutations, we provide insights into the potential for targeted therapies that could address not only UM but also other disorders associated with GNAQ/GNA11 mutations. Moreover, we discuss the role of SOX10-positive perivascular cells that may be implicated in the complex pathophysiology of GNAQ/GNA11-related entities. Understanding the common molecular foundation of these conditions opens new ways for research and treatment opportunities, potentially leading to more effective, personalized therapeutic strategies.

Incidental Vascular Lesion in Explanted Liver: A Rare Case Report and Review of the Literature

Hepatic small vessel neoplasm (HSVN) is a rare vascular hepatic lesion that is usually an asymptomatic incidental finding. Here we present a case of a 66-year-old male with HSVN who was discovered to have a lesion presenting as a small nodule in an explanted liver. HSVN is a recently described hepatic vascular lesion that has been previously underdiagnosed. It has an uncertain long-term malignant potential, so close follow-up is recommended.

Hepatic small vessel neoplasm: not totally benign, not yet malignant

Hepatic small vessel neoplasm (HSVN) is a rare vascular tumor with few reports in the literature. While imaging findings may show characteristic enhancement patterns, limited available literature may not reveal the full potential for image-based diagnosis. Histologically, HSVN mimics other entities, though certain morphologic and immunohistochemical findings provide clues for diagnosis. However, HSVN still provides diagnostic challenges, especially on core biopsies with limited material for morphologic and molecular evaluation. While current recommendations are surgical resection and close observation, the long-term course of the tumor is unknown. We report a case of HSVN in a liver with additional feature of organized lymphoid aggregates necessitating additional hematopathology consultation and workup to rule out concurrent entities.

Mesenchymal Neoplasms of the Liver

Mesenchymal neoplasms of the liver can be diagnostically challenging, particularly on core needle biopsies. Here, I discuss recent updates in neoplasms that are specific to the liver (mesenchymal hamartoma, undifferentiated embryonal sarcoma, calcifying nested stromal-epithelial tumor), vascular tumors of the liver (anastomosing hemangioma, hepatic small vessel neoplasm, epithelioid hemangioendothelioma, angiosarcoma), and other tumor types that can occur primarily in the liver (PEComa/angiomyolipoma, inflammatory pseudotumor-like follicular dendritic cell sarcoma, EBV-associated smooth muscle tumor, inflammatory myofibroblastic tumor, malignant rhabdoid tumor). Lastly, I discuss metastatic sarcomas to the liver, as well as pitfalls presented by metastatic melanoma and sarcomatoid carcinoma.

Hepatic Small Vessel Neoplasm: A Case Report and Review of the Literature

Hepatic small vessel neoplasm (HSVN) is a recently described vascular neoplasm of the liver. It demonstrates an infiltrative growth pattern and lacks cytologic atypia and mitotic activity. So far, no cases of metastasis or disease recurrence after excision have been reported in the literature. In this report, we present the case of a 31-year-old woman with a lesion in segments VII-VIII of the liver who was referred to our surgical department due to right lumbar pain. She underwent an atypical wedge hepatectomy (segments VII, VIII) and cholecystectomy. The histopathology of the resected specimen confirmed a 40mm HSVN. The patient did not receive any adjuvant therapy and is scheduled for follow-up with serial magnetic resonance imaging (MRI) scans over the next five years due to the unknown malignant potential of the tumor.

Primary and secondary angiosarcomas of the liver: a multi-institutional study of 32 cases

Angiosarcomas involving the liver can be hepatic primary or metastasis from another anatomic site, which have not been systematically compared. We analyzed a series of liver biopsy or resection specimens carrying a diagnosis of angiosarcoma collected between 2005 and 2022 at 3 tertiary medical centers. The cohort included 32 patients (20 M and 12 F) with a median age of 64 years. Nineteen were primary hepatic angiosarcoma (PHA) and 13 metastatic angiosarcoma to liver (MA). Males were predominant in PHA (15/19, 78%) compared to MA (5/13, 38%, P = .025). There was no age difference between the 2 groups. Five cases had background hepatic cirrhosis, which more likely harbored PHA (4/5, 80%). Multifocality and multiorgan involvement were common in both groups. Tumor size was significantly larger in PHA than in MA (10.4 versus 4.7 cm, P < .01). Histologically, there were no differences in terms of tumor morphology (spindled versus epithelioid) and growth patterns (vasoformative versus solid) between the 2 groups. Immunohistochemically, all tumor cells were positive for CD31 (28/28, 100%) and ERG (18/18, 100%). Molecular analysis in 5 cases demonstrated different mutation profiles involving different genes, including MTOR, PIK3CA, ARID1A, CDKN2A, PTEN, TP53, ATRX, KDR/VEGFR2, and so forth. On follow-up, 30 patients (93%) died of disease, with a median survival of 114 days. Univariate and multivariate analyses revealed PHA and epithelioid morphology to be associated with worse survival (P < .05), while treatment was associated with better survival (P < .001). Our results confirmed that angiosarcoma, particularly PHA, is extremely aggressive. Epithelioid morphology is an adverse prognosticator and may be used for tumor subclassification.

Hepatic Small Vessel Neoplasm Mimics Prostate Cancer on 18 F-DCFPyl PET/CT

ABSTRACT

18 F-DCFPyl is a Food and Drug Administration-approved radiotracer that targets prostate-specific membrane antigen and is used in the detection of recurrent or metastatic prostate cancer. As its use has increased, a growing number of nonprostatic disease entities have been identified that express prostate-specific membrane antigen and can mimic prostate cancer. Thus, the interpreting physician must also consider other variables such as serum prostate-specific antigen levels and the distribution of uptake to avoid an inappropriate diagnosis of metastatic prostate cancer. We describe 18 F-DCFPyl uptake associated with a hepatic small vessel neoplasm, an association previously undescribed in the literature.

Multiple hemangiomas (hepatic small vessel neoplasia) in the liver with Budd-Chiari syndrome

Hepatic small vessel neoplasia (HSVN) is a recently recognized hemangioma of the liver with uncertain malignant potential. Almost all the patients are asymptomatic. Budd-Chiari syndrome (BCS) is a rare disorder characterized by noncardiogenic hepatic venous outflow obstruction. Benign hepatocellular nodules have been acknowledged for a long time in the liver with the chronic BCS. However, there has been no case report of BCS associated with HSVN. The patient was diagnosed with BCS 13 years ago. The imaging test initially displayed multiple hepatic nodules that were suspected of benign hepatocellular nodules. They gradually increased in size and number in the course of the disease. At an autopsy, these nodules were confirmed to be multifocal HSVN. The tumor of the present case could not be proved to have GNAQ and GNQ14 mutations. We describe the case focusing on the chronological imaging changes and discuss on the relationship between BCS and HSVN.

Benign liver tumours: understanding molecular physiology to adapt clinical management

Improvements in understanding the pathophysiology of the different benign liver nodules have refined their nosological classification. New criteria have been identified using imaging, histology and molecular analyses for a precise diagnosis of these tumours. Improvement in the classification of liver tumours provides a more accurate prediction of disease progression and has modified patient management. Haemangioma and focal nodular hyperplasia, the most common benign liver tumours that develop in the absence of chronic liver disease, are usually easy to diagnose on imaging and do not require specific treatment. However, hepatocellular adenomas and cirrhotic macronodules can be difficult to discriminate from hepatocellular carcinoma. The molecular subtyping of hepatocellular adenomas in five major subgroups defined by HNF1A inactivation, β-catenin mutation in exon 3 or exon 7/8, and activation of inflammatory or Hedgehog pathways helps to identify the tumours at risk of malignant transformation or bleeding. New clinical, biological and molecular tools have gradually been included in diagnostic and treatment algorithms to classify benign liver tumours and improve patient management. This Review aims to explain the main pathogenic mechanisms of benign liver tumours and how this knowledge could influence clinical practice.

Anastomosing hemangioma of the liver: An unusual variant in abdominal MRI imaging

The liver is a rare site for anastomosing hemangiomas with only a few cases reported that characterize the lesions on magnetic resonance imaging (MRI). These lesions may be underreported due to overlapping features with classic hemangiomas. Anastomosing hemangiomas have a well-defined histological profile and are often diagnosed by biopsy in the setting of atypical imaging features.  We report a case of biopsy-proven hepatic anastomosing hemangioma found on a screening MRI for hepatocellular carcinoma in a 52-year-old female with cirrhosis. This lesion initially demonstrated interval growth but has shown no local recurrence in the 2-year surveillance period following microwave ablation.

Multifocal hepatic small vessel neoplasm with spleen dissemination

Among liver vascular tumours, hepatic small vessel neoplasm (HSVN) has been recently identified as a rare infiltrative vascular neoplasm whose malignant potential is yet to be fully ascertained. About 30 cases of HSVN have been described so far. The most common clinical presentation is an asymptomatic solitary liver lesion. Multifocal disease has been described in literature; however, to date, there are no reports of disease dissemination to other organs. Here we report a case of multifocal HSVN with synchronous spleen secondary lesions.

The genetics of vascular tumours: an update

Recent molecular advances have shed significant light on the classification of vascular tumours. Except for haemangiomas, vascular lesions remain difficult to diagnose, owing to their rarity and overlapping clinical, radiographic and histological features across malignancies. In particular, challenges still remain in the differential diagnosis of epithelioid vascular tumours, including epithelioid haemangioma and epithelioid haemangioendothelioma at the benign/low-grade end of the spectrum, and epithelioid angiosarcoma at the high-grade end. Historically, the classification of vascular tumours has been heavily dependent on the clinical setting and histological features, as traditional immunohistochemical markers across the group have often been non-discriminatory. The increased application of next-generation sequencing in clinical practice, in particular targeted RNA sequencing (such as Archer, Illumina), has led to numerous novel discoveries, mainly recurrent gene fusions (e.g. those involving FOS, FOSB, YAP1, and WWTR1), which have resulted in refined tumour classification and improved diagnostic reproducibility for vascular tumours. However, other molecular alterations besides fusions have been discovered in vascular tumours, including somatic mutations (e.g. involving GNA family and IDH genes) in a variety of haemangiomas, as well as copy number alterations in high-grade angiosarcomas (e.g. MYC amplifications). Moreover, the translation of these novel molecular abnormalities into diagnostic ancillary markers, either fluorescence in-situ hybridisation probes or surrogate immunohistochemical markers (FOSB, CAMTA1, YAP1, and MYC), has been remarkable. This review will focus on the latest molecular discoveries covering both benign and malignant vascular tumours, and will provide practical diagnostic algorithms, highlighting frequently encountered pitfalls and challenges in the diagnosis of vascular lesions.

Hepatic small vessel neoplasm - A systematic review

Background

Hepatic small vessel neoplasm (HSVN) is a recently described vascular neoplasm of the liver that can mimic hepatic angiosarcoma (AS) because of its infiltrative nature but is considered biologically less aggressive. We carried out a systematic review of the literature after previously coming across a case of HSVN [1] to guide our surveillance.

Methods

We conducted a systematic review for all cases using PubMed, EMBASE, Cochrane Central Register of Controlled Trials, case report journals and Google Scholar according to the PRISMA guidelines using the terms “hepatic small vessel neoplasm” or “hepatic small vessel neoplasia” with no language restrictions. The review was registered with Research Registry (UIN: reviewregistry1127) [2].

Results

We identified 69 articles, of which 6 articles were eligible after screening. A total of 23 cases were identified. Median age was 58 (range 24–83 years) with a male preponderance (17 M:6F). Mean tumour size was 2.8 cm (range 0.2–15.9 cm). Mean follow-up was 7 months (range 1–24 months) with no reported evidence of recurrence in both patient groups with no residual disease or with positive margins after resection.

Discussion

HSVN appears to demonstrate a benign clinical course with no reported recurrences or metastatic disease. Long-term follow-up data will further supplement our understanding of these tumours and guide future management.

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HSVN is a recently described neoplasm with uncertain long-term malignant potential.

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23 cases have been identified, mean follow-up was 7 months (range 1–24 months).

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There is no reported evidence of recurrence in patients with no residual disease.

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There is no reported evidence of recurrence in patients with residual disease.

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Follow-up is limited in reported cases.

Recent Advances in Digestive Tract Tumors: Updates From the 5th Edition of the World Health Organization "Blue Book"

CONTEXT.—

The World Health Organization Classification of Tumours: Digestive System Tumors, 5th edition, was published in 2019 and shows several impactful changes as compared with the 4th edition published in 2010. Changes include a revised nomenclature of serrated lesions and revamping the classification of neuroendocrine neoplasms. Appendiceal goblet cell adenocarcinoma is heavily revised, and intrahepatic cholangiocarcinoma is split into 2 subtypes. New subtypes of colorectal carcinoma and hepatocellular carcinoma are described. Precursor lesions are emphasized with their own entries, and both dysplastic and invasive lesions are generally recommended to be graded using a 2-tier system. Hematolymphoid tumors, mesenchymal tumors, and genetic tumor syndromes each have their own sections in the 5th edition. New hematolymphoid lesions include monomorphic epitheliotropic intestinal T-cell lymphoma; duodenal-type follicular lymphoma; intestinal T-cell lymphoma, not otherwise specified; and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. This paper will provide an in-depth look at the changes in the 5th edition as compared with the 4th edition.

OBJECTIVE.—

To provide a comprehensive, in-depth update on the World Health Organization classification of digestive tumors, including changes to nomenclature, updated diagnostic criteria, and newly described entities.

DATA SOURCES.—

The 5th edition of the World Health Organization Classification of Tumours: Digestive System Tumours, as well as the 4th edition.

CONCLUSIONS.—

The World Health Organization has made many key changes in its newest update on tumors of the digestive system. Pathologists should be aware of these changes and incorporate them into their practice as able or necessary.

A Novel Entity Among Vascular Liver Tumors: The First Reported Liver Transplantation. Is It Feasible?

Liver transplant could be considered for certain tumors even if there is still dubious indication, as in the case of hepatic small vessels neoplasms that pose a difficult differential diagnosis with liver angiosarcoma. Liver transplant could be the best choice for patients with stable or slow-progressing tumors, for young patients with impaired quality of life, and when it would use organs that would be otherwise discarded but are capable of affording a good function. Vascular tumors are very heterogeneous cancers and our case represents the first description of a new histologic lesion that cannot be included in any of the pre-existing diagnostic categories. In our paper we want to present our decision to transplant a patient in whom the diagnosis was hepatic small vessels neoplasms (but was still in doubt for angiosarcoma as suggested by pathologists form other institutions). Furthermore, we want to highlight that after liver transplant, a new lesion never described before resulted from the specimen analysis that does not fit any of the pathologic diagnostic categories. This finding could open a scenario for additional improvement in molecular analysis in order to differentiate liver vascular tumors or even single lesion histotypes. This article emphasizes how little we know about the real behavior of liver vascular tumors and their clinical and therapeutic outcomes; we want to raise a question about the possibility for liver transplant in the setting of tumors not yet fully known and in which, in cases of diagnostic doubts, this option has been traditionally excluded, possibly bypassing ethical implications by using marginal donors.

Hepatic small vessel neoplasm case report: A surveillance conundrum

INTRODUCTION

Hepatic small vessel neoplasm (HSVN) is a recently described vascular neoplasm of the liver that can mimic hepatic angiosarcoma (AS) because of its infiltrative nature but is considered benign or, at most, low-grade. HSVN appears to demonstrate a benign clinical course with no reported recurrences or metastatic disease, although its long-term malignant potential is uncertain.

CASE PRESENTATION

We present a 57-year-old man with an incidentally growing segment VII lesion that displayed features concerning for a neoplasm. He underwent a posterior sectionectomy and final histopathology confirmed a 27 mm HSVN. As the long-term malignant potential of HSVN is uncertain, he will be followed up with serial MRI scans over the next 5 years.

DISCUSSION

HSVN is a recently described entity, it is uncertain what the long-term malignant potential of HSVN can be. Reported cases have not shown any evidence of disease progression.

CONCLUSION

There are no clear guidelines established on the duration of the follow-up of HSVN. More research needs to be done to determine further the natural history of these tumours and possible radiological criteria.

Combined Inhibition of Gαq and MEK Enhances Therapeutic Efficacy in Uveal Melanoma

PURPOSE

All uveal melanoma and a fraction of other melanoma subtypes are driven by activation of the G-protein alpha-q (Gαq) pathway. Targeting these melanomas has proven difficult despite advances in the molecular understanding of key driver signaling pathways in the disease pathogenesis. Inhibitors of Gαq have shown promising preclinical results, but their therapeutic activity in distinct Gαq mutational contexts and in vivo have remained elusive.

EXPERIMENTAL DESIGN

We used an isogenic melanocytic cellular system to systematically examine hotspot mutations in GNAQ (e.g., G48V, R183Q, Q209L) and CYSLTR2 (L129Q) found in human uveal melanoma. This cellular system and human uveal melanoma cell lines were used in vitro and in in vivo xenograft studies to assess the efficacy of Gαq inhibition as a single agent and in combination with MEK inhibition.

RESULTS

We demonstrate that the Gαq inhibitor YM-254890 inhibited downstream signaling and in vitro growth in all mutants. In vivo, YM-254890 slowed tumor growth but did not cause regression in human uveal melanoma xenografts. Through comprehensive transcriptome analysis, we observed that YM-254890 caused inhibition of the MAPK signaling with evidence of rebound by 24 hours and combination treatment of YM-254890 and a MEK inhibitor led to sustained MAPK inhibition. We further demonstrated that the combination caused synergistic growth inhibition in vitro and tumor shrinkage in vivo.

CONCLUSIONS

These data suggest that the combination of Gαq and MEK inhibition provides a promising therapeutic strategy and improved therapeutic window of broadly targeting Gαq in uveal melanoma.See related commentary by Neelature Sriramareddy and Smalley, p. 1217.

[Liver sinusoids: pathology of endothelial findings]

This review covers a spectrum of pathologic changes and diseases involving hepatic sinusoids. In the majority of patients, clinical findings are rather uncharacteristic such as hepatomegaly, portal hypertension, or lingering liver failure of unknown origin. In contrast to more common hepatic disorders, characteristic clinical, serological, immunoserological, and radiographical findings are lacking. In these cases, biopsy findings may be crucial to guide treatment decisions. This review covers a variety of hepatic disorders that practicing pathologists may encounter in their clinical routine.

Spontaneous intra-adrenal massive hematoma: possible extreme evolution of a non-secreting untreated adrenal adenoma

The spontaneous adrenal hematoma is a rare event. An 83-year-old male patient presented a 26-cm asymptomatic retroperitoneal mass of doubtful renal–adrenal origin. He had been evaluated 10 years before for an adrenal incidentaloma of 2.3 cm and had refused surgery when it had reached 7 cm. Later, the mass enlarged to 26 cm and was surgically removed through an open anterior approach. The histopathology showed a solid 4 kg mass of fibrinoid–hemorrhagic material, partially necrotic, mixed with adrenal tissue, with a well-vascularized capsule. No relapse is present at 6-month follow-up. This is the largest case described of spontaneous intra-adrenal hematoma in a case with previous non-secreting adrenal adenoma. The hematoma (a 4 kg mass) developed 10 years after the first diagnosis and exposed the patient to potential damage of the surrounding organs and to high-risk abdominal surgery. Long-term follow-up of non-secreting adrenal adenomas should be recommended.

Frequent GNAQ and GNA14 Mutations in Hepatic Small Vessel Neoplasm

Hepatic small vessel neoplasm (HSVN) is a recently described infiltrative vascular neoplasm of the liver, composed of small vessels. Although the infiltrative nature can mimic angiosarcoma, HSVN are thought to be benign or low-grade neoplasms because they lack cytologic atypia and increased proliferation. To characterize the molecular pathogenesis of HSVN, we performed both targeted panel sequencing and exome sequencing on 18 benign or low-grade vascular neoplasms in the liver including 8 HSVN, 6 classic cavernous hemangioma (CH), and 4 variant lesions (VL) with overlapping features between HSVN and CH. All 18 lesions had simple genomes without copy number alterations. In total, 75% (6/8) of HSVN demonstrated known activating hotspot mutations in GNAQ (2/8, p.Q209H) or GNA14 (4/8, p.Q205L), and the remaining 2 had the same missense mutation in GNAQ, p.G48L, which has not been previously described. 25% (1/4) of VL had a hotspot GNAQ p.Q209H mutation and another VL had a GNAQ p.G48L mutation. Known pathogenic mutations were not identified in any of the 6 CH. These data suggest that HSVN share a similar molecular biology to several other vascular lesions (congenital hemangioma, tufted angioma, anastomosing hemangioma, lobular capillary hemangioma, and kaposiform hemangioendothelioma) recently reported to have GNAQ, GNA11, or GNA14 mutations.

Anastomosing hemangioma of liver

Anastomosing hemangiomas are a rare subtype of benign vascular hemangioma which most commonly arise in the genitourinary tract and retroperitoneum. In only a small number of reports has this entity been shown originating within the liver parenchyma. Despite their benign behavior, on contrast-enhanced computer tomography and magnetic resonance imaging studies anastomosing hemangiomas can demonstrate enhancement characteristics similar to primary and metastatic liver lesions. This case report highlights the imaging features of this entity and provides a brief review of the limited literature that exists on this rare hepatic lesion.

Malignant hepatic vascular tumors in adults: Characteristics, diagnostic difficulties and current management

Malignant vascular tumors of the liver include rare primary hepatic mesenchymal tumors developed in the background of a normal liver parenchyma. Most of them are detected incidentally by the increased use of performing imaging techniques. Their diagnosis is challenging, involving clinical and imaging criteria, with final confirmation by histology and immunohistochemistry. Surgery represents the mainstay of treatment. Liver transplantation (LT) has improved substantially the prognosis of hepatic epithelioid hemangioendothelioma (HEHE), with 5-year patient survival rates of up to 81%, based on the European Liver Intestine Transplantation Association-European Liver Transplant Registry study. Unfortunately, the results of surgery and LT are dismal in cases of hepatic angiosarcoma (HAS). Due to the disappointing results of very short survival periods of approximately 6-7 mo after LT, because of tumor recurrence and rapid progression of the disease, HAS is considered an absolute contraindication to LT. Recurrences after surgical resection are high in cases of HEHE and invariably present in cases of HAS. The discovery of reliable prognostic markers and the elaboration of prognostic scores following LT are needed to provide the best therapeutic choice for each patient. Studies on a few patients have demonstrated the stabilization of the disease in a proportion of patients with hepatic vascular tumors using novel targeted antiangiogenic agents, cytokines or immunotherapy. These new approaches, alone or in combination with other therapeutic modalities, such as surgery and classical chemotherapy, need further investigation to assess their role in prolonging patient survival. Personalized therapeutic algorithms according to the histopathological features, behavior, molecular biology and genetics of the tumors should be elaborated in the near future for the management of patients diagnosed with primary malignant vascular tumors of the liver.

Vascular tumours of the liver: a particular story

Vascular tumours of the liver represent an underrated chapter of medical and surgical hepatology. These tumours cover a wide spectrum ranging from the frequent and most benign hepatic haemangioma (HH), via the rare and intermediately aggressive hepatic epithelioid haemangioendothelioma (HEHE) to the rare and most malignant hepatic haemangiosarcoma (HHS). In contrast to the treatment algorithms for hepatocellular and cholangiocellular cancer, the diagnostic and therapeutic approaches to HEHE and HHS are not well developed. The related uncertainty is explained by their rare occurrence and their protean clinical, morphological (imaging) and histopathological presentation and behaviour. This article gives an update about these particular tumours based on the analysis of the recent literature and of the studies on vascular tumours published by the European Liver Intestine Transplantation Association (ELITA)-European Liver Transplant Registry (ELTR). It focuses also on the place of liver transplantation (LT) in the respective therapeutic algorithms. The differential diagnosis between these vascular and other tumour types may be very difficult. Correct diagnosis is of utmost importance and is based on a high index of clinical suspicion and on the integration of clinical, radiological, histological [including immunohistochemistry (IHC) and molecular biology findings]. Surgery, be it partial or total hepatectomy (LT), should be proposed whenever possible, because it is the therapeutic mainstay. In HEHE, LT provides excellent results, with long-term disease-free survivals (DFS) reaching 75%. Good results can be obtained even in case of (frequent) extrahepatic spread. Based on the extensive ELITA-ELTR study a HEHE-LT prognostic score has been proposed in order to estimate the risk of recurrence after LT. In contrast, results of surgery and LT are extremely poor for HHS, for the almost invariably rapid recurrence (within 6 months) and related death within 2 years. LT remains a contraindication for HHS. Due to the still important recurrence rate after surgical resection (25% in HEHE and almost 100% in HHS), there is an urgent need to develop pharmacological treatments targeting angiogenic and non-VEGF angiogenic pathways. To date, some prospective pilot studies and case reports have shown some short-term stabilisation of the disease in small groups of patients. In order to make progress, combination of surgery, anti-angiogenic and immunotherapy seems worthwhile. To complete the panel of vascular liver tumours, infantile haemangioendothelioma, haemangiopericytoma, nodular regenerative hyperplasia (NRH) and hepatic small vessel neoplasms (HSVN) are also discussed.

Imaging and Pathologic findings of Hepatic Small Vessel Hemangioma

Hepatic small vessel hemangioma represents a distinct yet very rare pathologic entity of the liver. The entity has also been in the past referred to as adult capillary hemangioma of the liver and congenital noninvoluting hemangioma. Imaging findings are not definitive and biopsy or resection is ultimately necessary. Pathologically these represent vasoformative abnormalities with infiltrative margins that can potentially mimic hepatic angiosarcoma. Immunohistochemistry can help differentiate hepatic small vessel hemangioma from angiosarcoma. Given the infiltrative growth pattern and unknown outcomes, resection and or close follow up has been recommended. Recently the term hepatic small vessel neoplasm has been coined in view of the unknown outcomes and some concerning findings on molecular analysis. We report 2 cases of this unusual entity and describe its imaging, gross pathologic, histopathologic, and immunohistochemical features.

Resection of the largest reported hepatic small vessel neoplasm

Hepatic small vessel neoplasm (HSVN) is a recently described vascular neoplasm of the adult liver. The neoplastic cells are positive for markers of vascular lineage (CD31, CD34, FLI-1). The distinctive morphology and infiltrative borders separate HSVN from benign vascular tumors such as cavernous hemangioma, while lack of atypical morphologic features, low to absent mitotic activity and low proliferation index distinguish it from malignant vascular tumors such as epithelioid hemangioendothelioma and angiosarcoma. Due to its infiltrative nature and lack of adequate follow-up information, the benign versus low-grade nature of this tumor is currently uncertain. We present a patient with resected HSVN involving all but the right posterior section of the liver, making this case the largest reported in the current literature.

Recurrent GNAQ mutations in anastomosing hemangiomas

Anastomosing hemangiomas are recently described benign vascular lesions that occur chiefly in the genitourinary tract and paravertebral soft tissues. Owing to their rarity and unusual cytoarchitectural features, anastomosing hemangiomas are frequently confused with low-grade angiosarcomas. The specific genetic alterations underlying these lesions are currently unknown. We performed capture-based next-generation DNA sequencing analysis on 13 anastomosing hemangiomas and identified frequent somatic mutations in the heterotrimeric G-protein alpha-subunit, GNAQ. Nine of 13 cases (69%) harbored a somatic mutation at GNAQ codon 209, a known hotspot that is commonly mutated in uveal melanoma and blue nevi, as well as various congenital vascular proliferations. No other pathogenic or likely pathogenic mutations were identified in these genetically simple lesions. The finding of a recurrent driver mutation in the G-protein signal transduction pathway provides strong evidence that anastomosing hemangiomas are indeed clonal vascular neoplasms.