Diagnosis of perinephric retroperitoneal lymphangioma supported by contrast-enhanced ultrasound (CEUS)

1 Introduction

Lymphangiomas are a rare condition, which are characterized by multiple cystic lesions of a single or multiple organs that are thought to originate from intrauterine atypically distended and connected lymphatic tissue [4]. Though these cysts are not considered as malignant, problems may arise through expansion with compression and infiltration of surrounding structures. Most common sites of occurrence are the lungs and bones, although they can occur in all organ systems connected to the lymphatic system. About three quarters of the cases show an involvement of the skeletal system [2]. Because of the rare occurrence of lymphangiomas, they are often misdiagnosed and the incidence of the disease is still unknown, while it is mostly diagnosed in children and young adolescents without showing gender or ethnical dependencies. Lymphangiomas can show an extensive range of different imaging features making it a challenging disease to diagnose, therefore diagnostic imaging options include all main radiological imaging modalities like contrast-enhanced computed tomography (CE-CT), magnetic resonance imaging (MRI), and sonography, however biopsy with histological workup is considered as the gold standard [6, 8]. Therapeutic options depend on the extend of expansion and resulting symptoms and include medication therapy, radiation therapy and surgical intervention [3, 7].

2 Case report

A 56-year-old asymptomatic woman was referred by her general practitioner with a suspicious right-sided cystic renal mass seen in conventional B-mode ultrasound showing multiple septa suggestive of a complicated renal cyst (Fig. 1). The general physical examination was without signs and symptoms. For further diagnosis, conventional B-mode ultrasound combined with color Doppler of the kidneys was performed. Ultrasound with a 9 MHz multifrequency curved array probe including color Doppler and CEUS was done (Philips EPIQ 7 (Philips Medical Systems, Bothell, WA) and SonoVue^® (Bracco, Milan, Italy)) with storing of dynamic image sequences [5]. The authors followed the ethical guidelines for publication in Clinical Hemorheology and Microcirculation [1].

Conventional B-Mode ultrasound of the right kidney showed a 7×6 cm cystic, anechoic mass partly surrounding the lower pole of the kidney without demonstrable vascularization in color Doppler (Fig. 1). After intravenous injection of 1,4 mL of SonoVue^®, consisting of encapsulated microbubbles containing sulphurhexa-fluoride stabilized by a phospholipid shell- a weak contrast enhancement of the septa without tumorlike enhancement (Fig. 2) could be observed. Using the Bosniak criteria for the classification of cystic renal lesions the cystic mass was classified as Bosniak type II F and a follow-up ultrasound was recommended.

10 months later US demonstrated an increasing renal mass of 8×7 cm partially surrounding the lower third of the right kidney. CEUS revealed a normal contrast enhancement pattern of the right kidney and a separate comparable contrast enhancement of the whole cystic mass with septa adjacent to the kidney (Fig. 3 and Fig. 4), suspicious of a perinephric manifestation of a lymphangioma. With CEUS we were able to distinguish between the normal contrast enhancement pattern of the right kidney and the separate contrast enhancement of the perinephric mass excluding differential diagnoses, e.g. renal cell carcinoma. An additional abdominal CE-CT scan revealed similar findings regarding the cystic mass and additionally showed multiple osseous manifestations of the lymphangiomatosis in the lumbar column and pelvis confirming the diagnosis of lymphangiomatosis (Fig. 5).

3 Discussion

The diagnosis of lymphangioma is difficult considering the rare occurrence of the disease and the wide range of imaging features that can be found using cross-sectional imaging techniques. CEUS can add useful important diagnostic information by showing the separate contrast enhancement patterns of the healthy renal parenchyma and the lymphangioma. Therefore CEUS can be used to exclude differential diagnoses and visualize the full extent of the lymphangioma manifestation. The main differential diagnosis would be multiple oval shaped parapelvic cysts, but without vascularization of the septa this diagnosis was unlikely. Additionally, multiple parapelvic cysts are normally organized inside the parenchyma towards the hilus of the kidney and are not adjacent to kidney as described in this case. As a big advantage compared to CE-CT and MRI, CEUS is a fast, cost-saving, easy accessible non-ionizing radiation imaging modality that relies on a almost contraindication-free and non-nephrotoxic contrast agent, which is especially useful for patients with impaired renal function. CEUS seems to be a viable additional diagnostic tool for the workup of abdominal manifestations of lymphangiomas. In this case, CE-CT alone could not totally exclude a renal involvement of the cystic mass adjacent to the right kidney. CEUS made it possible to clearly differentiate between healthy renal parenchyma and the lymphangioma.

4 Conclusion

We describe the diagnosis of an abdominal lymphangioma using CEUS. With the use of CEUS it was possible to add valuable diagnostic information regarding the extent of the lymphangioma to surrounding tissue without the necessity to use additional ionizing radiation or nephrotoxic contrast agents. CEUS could be used to aid the diagnosis of lymphangioma and should be considered as a tool in the difficult diagnostic workup of lymphangiomas.