Mesothelial cyst of the round ligament of the liver.

A 34-year-old man was admitted in our department with a 3 months history of epigastric pain, abdominal distension and tenderness. Helical computed tomography scan and magnetic resonance imaging showed a 10 cm low-density fluid-filled polilobate cystic lesion with internal septations and calcifications located between the left lobe of the liver, shorter gastric curvature, pancreas and mesocolon. Laparoscopic exploration was performed. Macroscopically the lesion was a unilocular serous cyst with a thick fibrous wall. Histopathology revealed a thin fibrous wall with a single layer of flattened to cuboidal mesothelial cell lining lacking any cellular atypia. The patient is currently alive without evidence of recurrence at 6 months. Cysts of mesothelial origin are rare lesions seen more frequently in young and middle-aged women, mostly benign and located in the mesenteries or omentum. Diagnosis is usually based on clinical examination and radiographic imaging. Immunohistochemistry is used to differentiate histologic type, with simple mesothelial cysts being positive for cytokeratins and calretinin and negative for CD31. The laparoscopic approach appears safe, feasible and less-invasive without compromising surgical principles and today should be considered the gold standard in most cases.

INTRODUCTION

Mesenteric intra-abdominal cystic lesions have been recently classified on the basis of histopathological features.[123] Their distinction is important because the incidence, presentation, and biological behavior differ. Cysts of mesothelial origin are rare lesions seen more frequently in young and middle-aged women, mostly benign and located in the mesenteries or omentum. What makes our particular case interesting is that it arose within the round ligament of the liver in a male patient. Owing to the low incidence, etiology remains unclear although true simple mesothelial cysts are mainly congenital. Cyst size ranges from few centimeters to 40 cm.[2345]

CASE REPORT

A 34-year-old man was admitted in our department complaining for the last 3 months of epigastric pain, abdominal distension and tenderness. Past medical history was unremarkable. Physical examination revealed mild abdominal distension with a sense of fullness in the epigastric region. Blood tests were negative, and serum tumor markers (carcinoembryonic antigen, carbohydrate antigen [CA] 19–9, CA 72-4, α-fetoprotein) levels were within the normal range. Serum immune hemagglutination for echinococcus was negative as well. Helical computed tomography (CT) scan [Figure 1a] and magnetic resonance imaging (MRI) [Figure 1b] showed a 10 cm low-density fluid-filled polilobate cystic lesion with internal septations and calcifications located between the left lobe of the liver, shorter gastric curvature, pancreas and mesocolon. A presumed diagnosis of cystic lymphangioma was made, and laparoscopic exploration was planned. The cyst appeared located within the round ligament extending from the dorsal free margin of the falciform ligament to the anterior abdominal wall [Figure 2]. It was completely aspirated, dissected form the surrounding structures with ultracision harmonic scalpel and then removed with endobag. Macroscopically the lesion was a unilocular serous cyst with a thick fibrous wall. Cytologic examination of the cystic fluid was negative for malignancies. Histopathology revealed a thin fibrous wall with a single layer of flattened to cuboidal mesothelial cell lining lacking any cellular atypia [Figure 3]. Immunohistochemical staining was positive for cytokeratins. Post-operative course was uneventful, and the patient was discharged 2 days after the operation. The patient is currently alive without evidence of recurrence at 6 months.

Figure 1

Magnetic resonance imaging (a) and computed tomography scan (b) showed a low-density fluid-filled polilobate cystic lesion with internal septations and calcifications located between the liver, stomach and pancreas

Figure 2

Intraoperative view of the cyst before aspiration

Figure 3

Histopathologic examination showing a thin fibrous cyst wall lined by a single layer of flattened to cuboidal mesothelial cell

DISCUSSION

Most of the cysts of mesothelial origin are asymptomatic and represent incidental findings during the course of investigations for other reasons. However, the growth may produce non-specific symptoms depending on size and location. Diagnosis is usually based on clinical examination and radiographic imaging, including CT scan or MRI but precise site, and origin cannot always be determined. Moreover, precise pre-operative differential diagnosis with other intra-abdominal cystic lesions remains challenging. Immunohistochemistry is used to differentiate histologic type, with simple mesothelial cysts being positive for cytokeratins and calretinin and negative for CD31.[123] If symptoms or complications occur, complete surgical excision with clear margins in order to avoid the risk of recurrence is recommended, and prognosis is excellent.[2345] Different entities of the cystic lesions within the round ligament of the liver were described. Perivascular epithelioid cell tumor and fibroma with size over 5 cm were recently described.[67] The laparoscopic approach has been reported only in sparse cases of true simple mesothelial cyst, with different locations comparing to ours.[8910]

CONCLUSION

To the best of our knowledge, this is the first case reported treated with a laparoscopic approach. Laparoscopy appears safe, feasible and less invasive without compromising surgical principles and today should be considered the gold standard in most cases. In the presence of a voluminous mass, complete aspiration before excision may allow to achieve adequate space for dissection.