Pediatr Radiol (1993) 23:305-306

Pediatric Radiology 9 Springer-Verlag 1993

Cystic retroperitoneal lymphangioma: CT, ultrasound and MR findings R. Iyer 1, F. Eftekhari 1, D. Varma 1, N. Jaffe 2 Division of Diagnostic Imaging, The University of Texas, M. D. Anderson Cancer Center, Houston, Texas, USA 2 Division of Pediatrics, The University of Texas, M. D. Anderson Cancer Center, Houston, Texas, USA Received: 21 December 1992/Accepted: 9 February 1993

Abstract. A case of cystic r e t r o p e r i t o n e a l l y m p h a n g i o m a complicated by h e m o r r h a g e is r e p o r t e d in a 7-year-old b o y w h o p r e s e n t e d with an a b d o m i n a l mass. T h e mass which was partially obstructing the ureter was successfully resected. T h e imaging findings with emphasis on M R features are described.

Cystic l y m p h a n g i o m a s , also k n o w n as cystic hygromas, are relatively u n c o m m o n tumors, and those that occur in the r e t r o p e r i t o n e u m are even less c o m m o n . T h e ultrasound and C T characteristics of cystic r e t r o p e r i t o n e a l l y m p h a n g i o m a have b e e n described. We r e p o r t the M R findings of a h e m o r r h a g i c cystic r e t r o p e r i t o n e a l l y m p h a n gioma.

and Ta-weighted images and layering loci of hemorrhage were also noted on the T?-weighted images. At surgery, a large cystic mass (11 x 7 x 6 cm) with the gxoss appearance of a cystic hygroma was found arising in the retroperitoneum. The mass, which displaced the right colon inferolaterally, was adherent to the colon and duodenum and was virtually engulfing the right ureter, causing partial obstruction. The mass was filled with hemorrhagic fluid. The mass was gradually peeled off the ureter. Pathological examination showed a large cystic mass composed predominantly of one large cavity with focal loculations. The wall was composed of collagenous tissue. No endothelial lining was noted, having presumably been destroyed by hemorrhage. Smooth muscle was noted on one histological section. Even though no endothelial lining was noted, the findings were compatible with lymphangioma. The child made fast recovery and was discharged without any complications.

Discussion Case report A 7-year-old Korean boy with a 3-year history of intermittent abdominal pain that had recently exacerbated presented with an abdominal mass detected by his father. An abdominal CT scan (Fig. 1) showed a large predominantly low-attenuation mass involving the right hemiabdomen. The patient was referred to the University of Texas M.D. Anderson Cancer Center with a suspected diagnosis of Wilms' tumor. Physical examination revealed a soft, firm, mobile, nontender mass that measured approximately 10 x 11 cm, arose below the right costal margin and extended to the right iliac crest. Additional imaging procedures included an excretory urogram (Fig. 2), which showed cephalad displacement of the right kidney by a large mass causing moderate hydronephrosis and hydroureter. An ultrasound examination (Fig. 3) showed a large septated mass that appeared to arise in the retroperitoneum and separate from the right kidney. The mass exhibited fine diffuse internal echoes, suggesting either a solid mass or a cystic lesion containing debris. Spin-echo axial and coronal T1- and T2-weighted MR images (Fig. 4) showed a large cystic lesion arising in the right retroperitoneum separate from the right kidney. The mass exhibited high signal intensity on both T1Correspondence to: E Eftekhari, MD, Division of Diagnostic Imaging, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA

L y m p h a n g i o m a s m a y be considered the lymphatic analog of h e m a n g i o m a s of b l o o d vessels and m a y be classified histologically into three types: simple, cystic and cavernous, depending on the size of the dilated lymphatics [1]. Cystic l y m p h a n g i o m a s (cystic h y g r o m a s ) are multilocular cystic masses containing either clear or chylous fluid [2]. T h e cyst wall and septa are c o m p o s e d of fibrous tissue, lymphatic tissue, vessels and s m o o t h muscle with an inner surface of endothelial cells [1]. T h e s e tumors p r o b a b l y develop because of a b n o r m a l early sequestration of the lymphatic vessels that do not develop c o m m u n i c a t i o n with n o r m a l lymphatic channels [1, 3, 4]. A p p r o x i m a t e l y 95 % of l y m p h a n g i o m a s occur in the neck and axillary region with the rest occurring in the mediastinum, m e s e n tery, internal viscera and bones [4]. L y m p h a n g i o m a s arising f r o m the m e s e n t e r y and o m e n t u m are called m e s e n teric and o m e n t a l cysts, respectively [1, 3]. Cystic r e t r o p e r i t o n e a l l y m p h a n g i o m a s generally present during infancy with a p p r o x i m a t e l y 90 % of patients presenting w h e n they are less than 2 years old [5]. Such cysts m a y also p r e s e n t in older children and adults b e c a u s e the mass m a y not b e c o m e clinically s y m p t o m a t i c in the r e t r o p e r i t o n e u m until it attains a large size [2].

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Fig. 1. Unenhanced CT scans reveals a large low-density septated mass (arrows).The right renal collection systemis distended secondary to ureteral obstruction noted on additional scans Fig.2o Excretory urogram showing obstruction of right ureter (black arrows) by the retroperitoneal mass (white arrows) Fig.3. Longitudinal sonogram showing a septated hypoechoicmass (white arrows) containing low-levelechoes and minimal sound transmission Fig.4. a Tl-weighted (TR/TE-717/20) axial MR image reveals a high-signal-intensitymass (arrows) with internal septations (arrowheads). Note distended right renal collection system. b Axial T2-weighted(TR/TE - 2000/80) MR image reveals a high-signal-intensitymass

(arrows).

c Axial Trweighted image at a more caudad level reveals layering loci of low-intensity hemorrhage (arrows)within the mass

Clinical symptoms usually result from compression on the gastrointestinal or genitourinary tract [1, 3]. Pain m a y result from h e m o r r h a g e or inflammation of the cyst. T h e endothelial lining m a y be destroyed by hemorrhage, as was noted in our case [1, 3]. Previous reports have emphasized the value of CT and ultrasound in characterizing cystic lymphangiomas in terms of their anatomic location and cystic nature. Imaging is useful to delineate the size and extent of the t u m o r preoperatively because surgical resection is the only effective treatment. Recurrence is usually related to inadequate surgical removal [6]. While M R findings of lymphangiomas in various locations in children have been reported [6], to our knowledge there are no reports on M R findings of retroperitoneal lymphangioma. Typically on M R imaging, most lymphangiomas show low signal intensity on Tl-weighted images (eitheT similar to or lower than adjacent muscle) and high signal intensity on T2-weighted images, reflecting the fluid content of the cystic mass [6]. In our case, the high signal intensity noted on both T1- and T2-weighted images and

the layering loci of high and low signal intensity on T2weighted images strongly suggested the presence of h e m o r r h a g e within the mass. This was confirmed surgically and on pathological evaluation.

References 1. Munechika H, Honda M, Kushihashi T, Koizumi K, Gokan T (1987) Computed tomography of retroperitoneal cystic lymphangiomas. J Comput Assist Tomogr 11:116 2. Rouch RF (1959) Retroperitoneal lymphangioma. Arch Surg 78: 45 3. Leonidas JC, Brill PW, Bhon I, Smith T (1978) Cystic retroperitoheal lymphangioma in infants and children. Radiology 127:203 4. Singh S, Baboo ML, Pathak IC (1971) Cystic lymphangioma in children: report of 32 cases including lesions at rare sites. Surgery 69:947 5. Rekhi BM, Esselstyn CB, Levy I, Mercer RD (1972) Retroperitoneal cystic lymphangioma: report of two cases and review of the literature. Cleve Clin Q 39:127 6. Siegel MJ, Glazer HS, St. Amour TE, Rosenthal DD (1989) Lymphangiomas in children: MR imaging. Radiology 170:467