Large lymphaticovenous malformation resection

Abstract

We report a case of a giant cardiac lymphaticovenous malformation arising from the atrioventricular groove in a 38-year old Caucasian female. Cardiac vascular lesions are rare and tend to be poorly described in the literature. Lymphaticovenous malformations are present at birth and develop due to errors in venolymphatic development. As the tumour enlarged, the patient experienced significant shortness of breath on exertion. At resection, the mass measured 6.0 cm anterior–posterior ×10.4 cm craniocaudal. The mass was found to be adhered tightly to the coronary sinus. Histologically, the lesion was composed of dilated vascular and lymphatic channels within a fatty stroma. The mass was resected without complications.

CASE REPORT

A 38-year old Caucasian female presented with right lower quadrant abdominal pain. A pelvic and abdominal computed tomography (CT) revealed a benign ovarian cyst as the likely source of her abdominal pain, as well as an incidental cystic lesion located on the inferior–lateral left ventricular margin of the heart. On magnetic resonance imaging, the mass measured 4.0 cm anterior–posterior × 7.0 cm craniocaudal and was well circumscribed, with features suggestive of a complex pericardial cyst. A positron emission tomography scan revealed mild 18F-fluorodeoxy glucose activity in the crescentic and hypodense mass, favouring a benign lesion. She initially underwent a posterior–lateral thoracotomy for tissue diagnosis and anticipated resection. The mass, however, was deeply imbedded in, and adherent to, the atrioventricular (AV) groove, making a surgical approach inappropriate for resection, and therefore only a biopsy was performed. Subsequent, transesophageal echocardiography confirmed the mass to be arising from the AV groove and adjacent to the coronary sinus. The biopsy was initially diagnosed as a benign, richly vascularized, adipose neoplasm with a smooth muscle component. The patient was discharged home with no symptoms, however, over a 2-month period she developed shortness of breath, substernal chest pain on exertion and persistent tachycardia. An electrocardiogram showed sinus tachycardia with no evidence of ischaemia, and her troponin levels were normal. A repeat CT (Fig. 1) only 2 months after the original diagnostic CT showed interval enlargement of the mass to 6.0 cm anterior–posterior ×10.4 cm craniocaudal. The presumption was that her symptoms were due to compression from the mass. A median sternotomy was performed in order to safely resect the tumour on cardiopulmonary bypass. The tumour was resected from the AV groove and peeled off the anterior surface of the inferior pulmonary veins. A large 2-mm feeding vessel was found originating from the circumflex artery and was clipped and sutured (Fig. 2). A 1.0 × 3.0 cm portion of the roof of the coronary sinus was removed with the specimen due to tight adhesion of the tumour. The coronary sinus was repaired with an autologous non-treated pericardial patch. Grossly, the mass was spongy, cystic and purple-red (Fig. 2). The patient recovered well from surgery with no complications, and her chest pain was resolved as of 3-year follow-up.

Figure 1:

CT showing lymphaticovenous malformation adherent to the atrioventricular groove.

Figure 2:

An excised malformation with feeding vessel (arrow).

Histologically, the lesion consisted of a network of variably dilated and angulated vascular channels lined by a single, flat layer of endothelium, some suggestive of venules and veins. Some of the vascular channels had ill-formed walls of variable thickness with irregularly distributed fascicles of smooth muscle (smooth muscle actin, h-caldesmon and desmin positive) streaming from the vessel walls. In the fatty stroma between the vessels, there were haphazardly distributed smooth muscle fascicles along with the strands of collagen and clusters of lymphocytes. The majority of vessels had vascular endothelium (CD31 positive), and scattered podoplanin (D2-40)-positive dilated lymphatics were identified. Based on the histological features and staining pattern, the diagnosis of lymphaticovenous malformation was made.

DISCUSSION

Vascular malformations are structural abnormalities composed of capillary, arterial, venous, lymphatic or mixed elements [1]. Unlike vascular tumours, vascular malformations do not regress and are lined by a single layer of flat endothelial cells. Vascular malformations are further classified as slow-flow (capillary, lymphatic, venous or mixed) and fast-flow (arterial and arterio-venous) [2, 3]. Lymphatic malformations tend to cause a greater enlargement than other types of vascular malformations [3].

Lymphaticovenous malformations, more specifically, are composed of combined lymphatic and venous elements and were previously known as lymphangiohemangiomas or haemangiolymphangiomas. Lymphaticovenous malformations are rare and arise most often in the craniofacial region with cases reported in the mediastinum, lower extremities and large and small intestines [2, 4]. Like other vascular malformations, lymphaticovenous malformations are present at birth, enlarge as the patient ages and never involute.

Cardiac vascular malformations are rare and were previously termed haemangiomas or angiomas in the literature. In our case, the initial absence of cardiac symptoms supports the diagnosis of a congenital mixed vascular malformation that only became symptomatic following the rapid expansion in size. We were able to follow the size and growth of the mass prior to the appearance of symptoms. In addition, the patient's symptoms were similar to those of previously reported cases of patients having a cardiac mass, specifically dyspnoea. However, our patient also complained of substernal chest pain with exertion despite the lack of evidence of ischaemia.

From a surgical perspective, the approach needs to be well thought out. In this case, the initial posterior–lateral thoracotomy approach did not allow for a resection due to the position of the tumour within the AV groove. A biopsy showing benign pathology did allow the peace of mind for the patient while she recovered from her incision. Resection became indicated 2 months following the incidental discovery of the mass due to the development of symptoms, and the patient underwent a median sternotomy for definitive therapy. The patient's symptoms of shortness of breath completely resolved with resection, and she was back to work as a floor nurse in 2 months. At 3-year follow-up CT scan, there was no recurrence of the mass, and ejection fraction was 70%.

Conflict of interest: none declared.