Anastomosing hemangioma of the ovary – a comprehensive review of this rare ovarian entity

Anastomosing hemangioma is a rare benign vascular tumor reported to occur in the kidney, testis, paravertebral soft tissue, gastrointestinal tract, liver, and in rare instances, in the ovary.^1,2,3,4 It was first described in 2009 by Montgomery and Epstein.⁵ Since then, only a limited number of cases have been reported in the literature, contributing to its diagnostic uncertainty. Most cases of anastomosing hemangioma of the ovary presents as a solitary, well-circumscribed mass or is incidental findings.¹ Occasionally, ovarian anastomosing hemangiomas have been associated with ascites and elevated serum CA 125 levels raising concern for an epithelial malignancy. Ovarian hemangiomas can be mistaken for malignant ovarian tumors due to their appearance on imaging studies. Appropriate preoperative diagnostics, including ultrasound, MRI, and sometimes CT scans, are essential to differentiate hemangiomas from more serious conditions such as ovarian cancer, which would require a different surgical approach and postoperative management.^6,7

Histologically, anastomosing hemangioma is characterized by anastomosing sinusoidal capillary sized blood vessels lined by bland endothelial cells with hobnail appearance, in a hyalinized and edematous stroma. The cells may show minimal atypia, which can be mistaken for low-grade angiosarcoma.⁷ Immunohistochemical staining may reveal positivity for endothelial markers such as CD31 and CD34, aiding in its diagnosis.⁸

We reviewed the current and relevant literature on anastomosing hemangiomas of the ovary to increase awareness of this rare entity. Prior to our review, only 33 cases of anastomosing hemangioma of the ovary have been reported in the English-language literature.^{1,3,6,7,8,9,10,11,12,13,14,15} Most of reviews are presented as case reports or small case series, and the largest series includes 12 cases of anastomosing hemangioma of the ovary.⁹ To add to the literature, we present and describe our case of anastomosing hemangioma of the ovary.

The definition of anastomosing hemangioma was established in 2009.⁵ The most likely theory that explaining the pathogenesis of this phenomenom characterizes anastomosing hemangioma of ovary as behaving like enlarging follicles that cause pressure on the neighboring tissue and lead to the development of luteinized stromal cells.⁶

In our review of literature, we found 33 cases of anastomosing hemangiomas of the ovary reported in the English literature. In our case the patient was 60 years old, while the mean age in the previous literature was 52.9 years (range from 26 to 81) (Table 1). The tumor size ranged from 1 millimeter to 100 millimeters, with the mean size being 20.6 millimeters. In our case tumor size was 50 millimeters.

Anastomosing hemangioma of the ovary typically affects women in their middle age, although cases have been reported across a wide age range.⁶ Clinically, patients may present with nonspecific symptoms such as abdominal pain, discomfort, or palpable pelvic mass. However, due to its rarity and lack of specific clinical features, anastomosing hemangioma is often an incidental finding on imaging studies or during surgical exploration for unrelated conditions. The absence of pathognomonic symptoms underscores the importance of histopathological evaluation for definitive diagnosis.¹⁶ Radiological imaging, including ultrasound and MRI, may demonstrate a hypervascular mass, although definitive diagnosis often relies on histological examination following surgical excision.¹⁰ In our case, too, the ovarian mass was an incidental finding with no specific clinical signs. Tumor markers were all negative and the ultrasound results were non-specific. The final histologic findings were decisive for the final diagnosis.

Stromal luteinization as a unique feature of ovarian anastomosing hemangiomas was reported in 22 of 28 cases (78.6%), and in 5 cases this data was not available (Table 1). Some of the prior cases presented association between anastomosing hemangioma of ovary with ascites and elevated serum CA 125, mimicking an epithelial ovarian malignancy.^1,6,7 These findings were not observed in our experience.

Particular histologic characteristics are described as non-lobular proliferation of anastomosing capillary sized vessels with sinusoidal-like arrangements resembling the red pulp of the spleen, with vessels lined by bland endothelial cells.⁶ The lack of atypical endothelial cells and mitotic figures helps to differentiate anastomosing hemangiomas from its malignant counterpart, angiosarcoma.¹⁷ Evaluation of the entire anastomosing hemangioma lesion, when possible, reveals that its growth is limited, lacking a broadly infiltrative pattern. The differential diagnosis of anastomosing hemangioma also includes capillary hemangioma, cavernous hemangioma, hemangioendothelioma, epithelioid hemangioma, and non-neoplastic vascular proliferations.⁹

Surgical excision remains the cornerstone of management for anastomosing hemangioma of the ovary. Complete resection is curative in the majority of cases, with favorable long-term outcomes. Management decisions should be individualized based on factors such as tumor size, location, and patient preferences, with a focus on preserving ovarian function and fertility when feasible. Overall, the prognosis of anastomosing hemangioma of the ovary is excellent following complete surgical resection. Recurrence rates are low, particularly with adequate surgical margins. However, cases of recurrence have been reported, highlighting the importance of vigilant long-term surveillance.^18,19

Continued collaboration among multidisciplinary teams is essential to advance our understanding and improve outcomes for patients with this rare ovarian tumor. Although the preliminary imaging and initial microscopic features may appear alarming, careful microscopic examination reveals benign behaviour.¹⁰ There is a need to raise awareness of this unusual and rare entity to improve morphologic recognition and avoid misdiagnosis that could lead to unnecessary treatment or patient anxiety.

In conclusion, anastomosing hemangioma of the ovary is a rare vascular tumor that poses diagnostic challenges due to its histological resemblance to more aggressive lesions. Despite its benign nature, accurate diagnosis is essential to avoid unnecessary interventions and ensure appropriate management. Long-term follow-up is crucial due to reported cases of recurrence following incomplete resection. Further research is needed to better understand the pathogenesis of this rare ovarian tumor and to optimize diagnostic and therapeutic approaches. Increased awareness among clinicians and pathologists is essential for timely recognition and management of anastomosing hemangioma of the ovary, ultimately improving patient outcomes.