Presentation
Dermatitis. Rising amylase.
Patient Data
There is a large well-defined retroperitoneal lesion measuring 14.1 cm in maximum dimension. There is internal complexity and the impression of enhancement on the portal venous phase, though this is not certain in the absence of a pre-contrast series. No avid arterial enhancement.
The lesion lies above and wraps around the hepatic artery though there is no associated vessel stricturing. The mass runs alongside the superior mesenteric vein/splenic confluence and portal vein which are displaced but not stenosed.
The pancreas is in contact with the lesion but it is unclear whether this is arising from the pancreas. The pancreas appears normal with no features to suggest acute or chronic pancreatitis.
Normal biliary tree.
Arcuate ligament associated narrowing of the celiac axis. Otherwise patent non- stenosed abdominal vasculature.
Rest of the solid organs are unremarkable. Bowels are unremarkable. No free gas seen.
Unremarkable lung bases and bone review
Comment: Large well-defined retroperitoneal lesion with internal complexity but no overtly malignant features. This may represent a benign lymphatic malformation but a malignant retroperitoneal lesion such as sarcoma is a differential. The increasing amylase suggests mass effect on the pancreas which is concerning for growth.
Extracellular contrast (Gadovist) was utilized.
The hypoattenuating retroperitoneal mass on CT corresponds with a large retroperitoneal mass of heterogeneous T2 signal and low T1 signal, measuring 15 x 10 x 7.6 cm. The mass demonstrates gradual heterogeneous enhancement, a mixture of T2 shine through and mild diffusion restriction, and no frank fat signal. The mass displaces the adjacent viscera (including the stomach, pancreas, and left lobe of the liver) as well as the superior mesenteric vein, confluence of the SMV and splenic vein, and the portal vein; the portosystemic circulation remains patent.
Normal background liver. No liver metastases.
Conventional arterial anatomy (narrowed celiac axis with a median arcuate compression type picture).
Thin-walled gallbladder with small volume biliary sludge, without biliary dilatation.
Normal pancreas, adrenals, kidneys and spleen. No free abdominal fluid.
Impression:
Unusual large retroperitoneal mass with local mass effect but no local invasion. Felt unlikely to be of liver or pancreatic origin. Exact etiology unclear; a tumor of neural origin is likely the top differential, but a low-grade sarcoma is not excluded.
The mass abuts the stomach and duodenum and EUS-guided biopsy is the best option for tissue.
Case Discussion
The patient proceeded to an endoscopic ultrasound-guided biopsy of the lesion.
Histopathology demonstrated a spindle cell tumor admixed with ganglion cells giving a diagnosis of ganglioneuroma, with no evidence of malignancy.
The radiological appearances in this case are somewhat non-specific and the differential would include other neuromal tumors e.g. schwannoma.
The patient is awaiting discussion at the local sarcoma multidisciplinary team meeting to decide on further management.
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