Teaching Case

A 24-year-old man presented with a vague abdominal lump.

A 24-year-old man presented with a vague abdominal lump. On examination there was a non-tender ill-defined lump in the epigastrium, left hypochondrium and left lumbar region. Haematological profile and serum markers were unremarkable. Ultrasound performed elsewhere, showed large cystic mass in the lesser sac with septations. No solid component or debris was noticed. CT examination showed a large lobulated hypoattenuating cystic mass engulfing the distal body and tail of pancreas. It was homogeneous in appearance and demonstrated fluid attenuation. No overt solid component or calcification was present. No enhancement was evident on the post contrast scan. It was displacing the bowel loops to the right and demonstrated extension to the lumbar region. Intraoperatively the mass was found to be attached to the mid body and tail of pancreas. A subtotal resection of the mass was performed. Histologically the resected cystic lesion showed endothelial lined dilated lymphatics with lymph like fluid and fibrous stroma consistent with lymphangioma.

Abdominal lymphangiomas are rare, accounting for less than 1% of all lymphangiomas. Intra-abdominal lymphangiomas may be multiple or single, or unilocular or multilocular. In the abdomen they most commonly involve the mesentery and the retroperitoneum. Lymphangiomas are considered to be of pancreatic in origin if they are in the pancreatic parenchyma, immediately adjacent to the pancreas, or connected to the organ by a pedicle. Various theories have been postulated regarding the development of these laympahngiomas, including [1] developmental abnormality of the lymphatic channels [2] increased production and retention of lymphatic fluid, and [3] infection or inflammation of the lymphatic channels. Malignant transformations to lymphosarcoma or adenocarcinoma although extremely rare, have been reported in the literature.

These lesions are often incidental finding on abdominal imaging. Larger lesions may manifest with symptoms such as vague abdominal pain, abdominal distension or a palpable lump in the abdomen. Smaller lesions may remain asymptomatic and undetected. Patient with lymphangiomas can present with acute symptoms if the lymphatic cysts get complicated. These complications include cyst infection, intralesional haemorrhage, torsion or rupture of the cyst.

Ultrasonography shows a relatively well defined unilocular or multilocular, anechoic to hypoechoic mass which may demonstrate internal septae. CT shows a well circumscribed, thin walled, cystic mass which may exert mass effect on adjacent organs. MRI can in addition show thin septae, define structural interfaces better and is superior to CT in ruling out communication with the pancreatic duct. The differential diagnosis for cystic masses arising in the pancreas include pseudocyst, mucinous cystic neoplasm, solid and papillary epithelial neoplasm, intraductal papillary mucinous neoplasm, and cystic neuroendocrine tumour. As the imaging appearances of pancreatic lymphangiomas may sometimes overlap with these cystic masses, the diagnosis can be confirmed only by histopathological examination.