Lesser omental capillary-lymphatic-venous malformation with massive intralesional hemorrhage: A case report

Abstract

Lesser omental cystic capillary-lymphatic-venous malformation (CLVM) is a rare benign intra-abdominal vascular anomaly. We report the case of a 50-year-old female patient who was admitted to our hospital with epigastric pain. She was previously diagnosed with abdominal cystic lymphangioma. At the time of her visit to our hospital, abdominal computed tomography (CT) revealed massive intralesional hemorrhage. During tumor resection, the cystic lesion was found to originate from the lesser omentum. Histopathologically, the patient was diagnosed with CLVM instead of lymphangioma, based on the 2018 International Society for the Study of Vascular Anomalies (ISSVA) classification. Hemorrhage within the cyst may alter lesion imaging features, thereby complicating preoperative diagnosis. Preoperatively, we were unable to identify imaging features of vascular components other than the lymphatic component. In our case, the hemorrhage may have been caused by vascular structures pathologically identified within the lesion. Therefore, we speculated that previously reported cases of abdominal lymphangiomas complicated by hemorrhage may harbor combined vascular malformations had they been pathologically reclassified according to the 2018 ISSVA classification system. We report a case of lesser omentum CLVM that subsequently developed into intralesional hemorrhage, with a review of the relevant literature.

Introduction

Cystic lymphangiomas are benign congenital tumors of the lymphatic vessels, usually located in the subcutaneous tissue of the head, neck, and axillary regions, with less common abdominal localization [1,2]. Less than 1% of cases present with cystic lymphangiomas involving the mesentery, greater omentum, or retroperitoneum [3]. While most abdominal lymphangiomas are initially asymptomatic, symptoms, such as nausea, vomiting, and pain, gradually develop as they progress [1]. According to the International Society for the Study of Vascular Anomalies (ISSVA) classification published in 2018, lymphangiomas are classified as lymphatic malformations within the category of simple vascular malformations [4]. We report a rare case of a giant vascular malformation originating in the lesser omentum, initially diagnosed as an abdominal cystic lymphangioma. The lesion subsequently developed intralesional hemorrhage and was pathologically confirmed as a capillary-lymphatic-venous malformation (CLVM), categorized as a combined vascular malformation based on the resected specimen.

Case report

A 50-year-old female with a known history of type I neurofibromatosis was treated for epigastric pain with proton pump inhibitors by her local physician. However, as her symptoms failed to improve with medication, she was referred to our hospital. She had a history of and intraperitoneal cystic mass detected during a medical check-up 6 years prior. Contrast-enhanced abdominal CT (CECT) revealed an 18 cm multilocular cystic lesion within the abdominal cavity adjacent to the left hepatic lobe and lesser curvature of the stomach (Fig. 1). The cystic mass was a homogeneous, water-dense lesion that showed no contrast enhancement at the septa and wall; therefore, she was diagnosed with abdominal cystic lymphangioma. A follow-up visit was scheduled 6 months later; however, the patient did not return to the local clinic. At the time of her visit to our hospital, 6 years after the initial follow-up appointment, plain abdominal computed tomography (CT) revealed that the multilocular cystic lesion had increased to a maximum diameter of 24 cm and occupied the upper abdominal cavity. A high-density area was observed on the dorsal side of the cyst, which was interpreted as a hematoma inside the cystic tumor (Fig. 2). Serum hemoglobin level decreased from 9.0 g/dl to 7.7 g/dl in 1 day. Dynamic CECT showed slight enhancement of the septa and wall of the tumor; however, there were no signs of active bleeding or contrast-enhanced nodules within the cyst (Fig. 3). Radical intraperitoneal tumor resection was performed because massive bleeding within the cystic lesion was suspected. Intraoperatively, the cystic lesion was found to originate from the lesser omentum. Histopathological examination revealed that the cyst wall was composed of adipose and fibrous interstitial tissues, which contained vascular structures of various sizes, including lymphatic vessels, arteries, and veins (Fig. 4). According to the 2018 ISSVA classification, the patient was diagnosed with CLVM, categorized as a combined vascular malformation of the lesser omentum. The tumor was completely resected, and the patient was discharged 6 days after the surgery without complications.

Fig. 1.

Contrast-enhanced abdominal computed tomography (CT) performed at a local clinic 6 years ago showed an 18 cm multilocular cystic lesion (arrow) within the abdominal cavity adjacent to the left hepatic lobe and lesser curvature of the stomach (A) axial image and (B) coronal images.

Fig. 2.

A plain abdominal CT scan at our hospital showed that the multilocular cystic lesion had increased to maximum diameter of 24 cm, occupying the upper abdominal cavity. A high-density area was observed on the dorsal side of the cyst, interpreted as a hematoma (arrow).

Fig. 3.

Dynamic contrast enhanced CT did not show any sign of active bleeding nor contrast-enhanced nodules within the cyst. (A) Plain CT, (B) arterial phase and (C) venous phase.

Fig. 4.

Histopathological examination showed that the cyst wall was composed of adipose and fibrous interstitial tissue, which contained vascular structures of various sizes, including lymphatic vessels (asterisk), arteries (arrowhead), and veins (arrow). (A) H.E. x40, (B) EVG. x100 and (C) CD31. x100.

Discussion

Vascular malformations are categorized into 4 types according to the 2018 ISSVA classification: simple vascular malformations, combined vascular malformations, vascular malformations of major vessels, and vascular malformations associated with other anomalies [4]. In our case, the patient was initially diagnosed with a lymphangioma of peritoneal origin owing to its cystic appearance on CECT, which was classified as a lymphatic malformation of simple vascular malformations in the 2018 ISSVA classification. The most common sites of abdominal lymphangiomas are the retroperitoneum (23.9%), colon (21%), stomach (13.6%), small intestine (11.9%), mesentery (9.7%), greater omentum (4.5%), and lesser omentum (1.7%) [5]. Thus, its occurrence in the lesser omentum, as in our case, is exceedingly rare. Ultimately, this case was pathologically diagnosed as a CLVM, which fell within the category of combined vascular malformations. Combined vascular malformations are defined as the presence of 2 or more distinct vascular malformations in a single lesion. According to the ISSVA classification, combined vascular malformations involve combined multifocal lymphatic-venous malformations with both truncular and extratruncular components [6].

Abdominal ultrasonography (US) and CT are commonly used for diagnostic imaging to detect cystic lesions and assess their extent. On US, lymphangiomas typically appear as well-circumscribed, multilocular cystic lesions separated by thin internal septa [7]. Although echogenic debris may occasionally be observed, the cystic components are usually anechoic. Abdominal CT is valuable for differentiating lymphangiomas from other abdominal cystic lesions such as enteric duplication cyst, the enteric cyst, mesothelial cyst and nonpancreatic pseudocyst [8], as fluid components usually demonstrate homogeneous attenuation similar to that of water. Septal and cyst wall enhancements are frequently observed on CECT. Magnetic resonance imaging (MRI) typically reveals a water-like signal profile with low intensity on T1-weighted images and high intensity on T2-weighted images [9]. However, the occurrence of hemorrhage or infection within the cyst can profoundly modify these imaging characteristics, sometimes mimicking solid tumors, thereby complicating the preoperative diagnosis [2]. To date, the imaging features of combined vascular malformations have not been described systematically. Pham et al. described a case of pelvic CLVM in a 3-month-old male [6], characterized by multiloculated cystic masses with internal septation on Doppler US and MRI and septal enhancement on postcontrast MRI, consistent with lymphatic malformation. Furthermore, the presence of lamellar fluid–fluid levels on MRI indicated a combined lymphatic and venous component of vascular malformations. In our case, although septal and wall enhancements were identified, the cystic components were homogeneous and no fluid–fluid levels were detected. Consequently, the lesion was initially diagnosed as an abdominal cystic lymphangioma. We speculated that some abdominal cystic lesions diagnosed as lymphangiomas on imaging may include combined vascular malformations. However, distinguishing combined vascular malformations from lymphangioma through the slight enhancement of the septa and wall of the tumor is considered difficult based on our case.

Most abdominal lymphangiomas are asymptomatic, and massive intralesional hemorrhages are exceedingly rare. Llapur et al. reported a case of a 2-year-old female with hypovolemic shock caused by bleeding from an abdominal cystic lymphangioma [10]. Similarly, Mahmoudi et al. [11] reported a 3-year-old male with acute abdomen caused by intracystic hemorrhage from an omental cystic lymphangioma. They emphasized that acute abdomen in patients with abdominal lymphangioma may arise from intestinal obstruction due to volvulus, extrinsic compression and entrapment, or peritonitis secondary to rupture, torsion, hemorrhage into the cyst, or an infected cyst. To the best of our knowledge, there have been no reports of massive hemorrhage in adult patients with abdominal lymphangioma. The hemorrhage in our case may have been caused by the presence of vascular structures that were pathologically identified within the lesion. Furthermore, no previous reports have described massive hemorrhage in cases of combined vascular malformations such as CLVM. Therefore, we speculated that previously reported cases of abdominal lymphangiomas complicated by hemorrhage may harbor combined vascular malformations, had they been pathologically reclassified according to the 2018 ISSVA classification.

Conclusion

We report a rare case of a CLVM originating from the lesser omentum that subsequently developed into intralesional hemorrhage, initially diagnosed as an abdominal cystic lymphangioma. The possibility of intralesional hemorrhage should be carefully considered when a patient presents with acute abdominal symptoms because some abdominal cystic lesions initially diagnosed as lymphangioma on imaging may include combined vascular malformation.

Patient consent

Informed consent was obtained from the patient for the publication of this report and any accompanying images.

Author contributions

All authors made substantial contributions to data analysis or interpretation, drafted the manuscript, revised it critically for important intellectual content, approved the final version of the manuscript to be published, and agreed to be accountable for all aspects of the study.