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Anastomosing hemangiomas are benign vascular neoplasms consisting of thin-walled anastomosing vessels. These lesions have been just recently added to the WHO classification of soft tissue tumors in 2020 as a separate entity 1-3
Anastomosing hemangiomas are rare lesions with a wide range of distribution, usually but not exclusively seen in adults with some cases also reported in children 1,4.
The diagnosis of anastomosing hemangiomas is a histological one 1.
Diagnostic criteria according to the WHO classification of tumors: soft tissue and bone (5th edition) 1:
- anastomosing vascular channels with a hobnail endothelial cell lining
The following histological criterion is desirable:
- extramedullary hematopoiesis and hyaline globules
Many cases are found incidentally in imaging studies or on endoscopy due to visceral location. Superficial neoplasms might present as palpable nodules or masses with or without associated pain 1. Renal lesions might present with hematuria.
Pathologically anastomosing hemangiomas are poorly marginated lesions consisting of thin-walled interconnecting capillary-sized vessels with monolayered endothelial cells featuring a hobnail appearance 1-5.
The etiology of anastomosing hemangiomas is currently unknown 1.
Anastomosing hemangiomas are most commonly seen in the kidneys and retroperitoneum 1-5 but are generally found in multiple locations including the male and female genital tract, gastrointestinal tract, the liver the soft tissues and the skin 1,5.
Macroscopically anastomosing hemangiomas are well-delineated non-encapsulated lesions with a spongy hemorrhagic mahogany-like appearance 1,5. Tumor size is variable with examples up to 8 cm 4.
Microscopically anastomosing hemangiomas are characterized by the following histologic features 1-5:
- loosely lobulated structure
- anastomosing capillary-sized vascular channels
- scattered single-layered endothelial cells with hobnail morphology and no multilayering
- absent or rare mitotic activity
- no or at best mild cellular atypia
- common vascular thrombi
- extramedullary hematopoiesis in a fair number of cases
Tumors are associated with GNAQ or GNA14 mutations in a majority of cases 1,4.
On imaging, anastomosing hemangiomas are usually well-marginated, but otherwise, non-specific imaging features 1,4,6. Multifocal lesions have been documented.
On ultrasound, lesions have been characterized as hypoechoic with plenty of flow signals on color Doppler 7.
On CT lesions have been characterized as hyperdense or hypodense with avid enhancement but heterogeneous attenuation 1,4,7 also due to fatty components 6.
On MRI anastomosing hemangiomas have been described as well-defined lesions with cystic and solid components 4,7-9. Enhancement patterns have been described as variable, mimicking more aggressive lesions 4,10.
- T1: hypointense
- T2: iso to hyperintense
- T1 C+ (Gd): progressive centripetal enhancement
On FDG-PET minor tracer uptake has been observed 9.
The radiological report should include a description of the following:
- form, location and size
- tumor margins
- relation to organs and viscera
- relation to muscular fasciae and skeletal muscles in soft tissues
- relationship to local nerves and vessels
Treatment and prognosis
Anastomosing hemangiomas are benign lesions even in the setting of multicentricity or infiltrative growth 1. However, due to non-specific imaging features that overlap with several malignant tumors, they are often overtreated 4
History and etymology
Anastomosing hemangiomas have been first described by the American pathologists Elizabeth Montgomery and Jonathan I Epstein in 2009 2,4,5.
Conditions that can mimic the presentation and/or the appearance of anastomosing hemangiomas include the following:
- 1. Montgomery EA, Umetzu SE. Anastomosing haemangioma. In: WHO Classification of Tumours Editorial Board. Soft tissue and bone tumours. Lyon (France): International Agency for Research on Cancer; 2020. (WHO classification of tumours series, 5th ed.; vol. 3). https://publications.iarc.fr
- 2. Sbaraglia M, Bellan E, Dei Tos A. The 2020 WHO Classification of Soft Tissue Tumours: News and Perspectives. Pathologica. 2021;113(2):70-84. doi:10.32074/1591-951X-213 - Pubmed
- 3. Bansal A, Goyal S, Goyal A, Jana M. WHO Classification of Soft Tissue Tumours 2020: An Update and Simplified Approach for Radiologists. Eur J Radiol. 2021;143:109937. doi:10.1016/j.ejrad.2021.109937 - Pubmed
- 4. Lappa E & Drakos E. Anastomosing Hemangioma: Short Review of a Benign Mimicker of Angiosarcoma. Arch Pathol Lab Med. 2020;144(2):240-4. doi:10.5858/arpa.2018-0264-RS - Pubmed
- 5. Montgomery E & Epstein J. Anastomosing Hemangioma of the Genitourinary Tract: A Lesion Mimicking Angiosarcoma. Am J Surg Pathol. 2009;33(9):1364-9. doi:10.1097/PAS.0b013e3181ad30a7 - Pubmed
- 6. O'Neill A, Craig J, Silverman S, Alencar R. Anastomosing Hemangiomas: Locations of Occurrence, Imaging Features, and Diagnosis with Percutaneous Biopsy. Abdom Radiol (NY). 2016;41(7):1325-32. doi:10.1007/s00261-016-0690-2 - Pubmed
- 7. Xue X, Song M, Xiao W, Chen F, Huang Q. Imaging Findings of Retroperitoneal Anastomosing Hemangioma: A Case Report and Literature Review. BMC Urol. 2022;22(1):77. doi:10.1186/s12894-022-01022-7 - Pubmed
- 8. Cheon P, Rebello R, Naqvi A, Popovic S, Bonert M, Kapoor A. Anastomosing Hemangioma of the Kidney: Radiologic and Pathologic Distinctions of a Kidney Cancer Mimic. Curr Oncol. 2018;25(3):e220-3. doi:10.3747/co.25.3927 - Pubmed
- 9. Kishida N, Sentani K, Terada H et al. Anastomosing Haemangioma with Fatty Changes in the Perirenal Space: A Lesion Mimicking Liposarcoma. BJR Case Rep. 2018;4(2):20170022. doi:10.1259/bjrcr.20170022 - Pubmed
- 10. Merritt B, Behr S, Umetsu S, Roberts J, Kolli K. Anastomosing Hemangioma of Liver. J Radiol Case Rep. 2019;13(6):32-9. doi:10.3941/jrcr.v13i6.3644 - Pubmed