Keywords
18F-fluorodeoxyglucose positron emission tomography/computed tomography - portal vein
thrombosis - tumor thrombosis - venous thrombosis
A 73-year-old woman known for a remote history of pulmonary sarcoidosis and an invasive
ductal carcinoma of the breast, positive for estrogen and progesterone receptors,
treated by segmental mastectomy, radiation therapy, and ongoing hormone therapy presented
at oncology follow-up with systemic symptoms of fatigue, weight loss and night sweats
as well as postprandial abdominal pain 4 years after breast cancer diagnosis. Contrast
computed tomography (CT) abdomen revealed a soft-tissue mass posterior to the pancreas,
several enlarged retroperitoneal lymph nodes, and dilated portal vein. Focused abdomen
ultrasound proved portal vein thrombosis. Recurrence of breast cancer, lymphoma, and
sarcoidosis was entertained as diagnostic possibilities. 18F-fluorodeoxyglucose positron
emission tomography (18F-FDG PET)/CT was performed [Figure 1], revealing intense activity in the retroperitoneal mass and lymph nodes. Moreover,
metabolic activity extended along the portal vein, branching within the hepatic parenchyma
to involve most of the liver intrahepatic venous system, however with distinctively
less uptake than the extrahepatic tumors. This “tree-like” appearance was diagnostic
of acute portal vein thrombosis. The intrahepatic component is presumed nontumoral
(bland) thrombosis, from vascular occlusion of the extrahepatic portal system by the
retroperitoneal mass. Biopsy of the mass later confirmed undifferentiated adenocarcinoma
without breast cancer marker expression, presumably from the pancreatic origin.
Figure 1 (a) Transaxial 18F-fluorodeoxyglucose positron emission tomography image of the retroperitoneal
mass. (b) Corresponding transaxial computed tomography image. (c) Maximum Intensity
Projection of positron emission tomography image. 18F-fluorodeoxyglucose positron
emission tomography/computed tomography reveals intense activity in the retroperitoneal
mass (arrowhead frames) and lymph nodes (not displayed). Moreover, metabolic activity
along the portal vein, "tree-like" branching within the hepatic parenchyma to involve
most of the liver intrahepatic venous system (black arrowhead) is distinctively less
intense than the extrahepatic tumor. This appearance was diagnostic of acute portal
vein thrombosis
Due to neutrophils and macrophages activated by the acute inflammatory phase of venous
thrombosis, FDG-PET sports high sensitivity and specificity.[1],[2],[3],[4] Various cancers are associated with bland or tumor thrombosis, including hepatocellular
carcinoma, pancreaticobiliary carcinoma, renal cell carcinoma, and various adenocarcinomas.[5],[6],[7],[8],[9] As proposed by recent literature, FDG-PET may differentiate direct tumor invasion
from bland thrombus. Despite the fact that both acute bland thrombosis and tumoral
growth display metabolic activity, there seems to be a significant discrepancy in
the intensity of uptake in most cases, the former being less intense than the latter.[10] In addition, venous thrombosis uptake subsides in the chronic phase to normal values
at approximately 3 months, allowing for proper distinction from malignancy in the
absence of targeted treatment.[1],[2],[3],[4] As opposed to previously reported extensive portal vein tumor thromboses,[6] the current case illustrates the interesting pattern of branching metabolic activity
in an extensive portal vein thrombosis with mild intrahepatic intensity suggestive
of bland thrombosis, highlighting once more the instrumental role of FDG-PET in thrombosis
and cancer staging. Unfortunately, in this case, cancer stage was not suitable for
curative intent, and the patient received appropriate palliative therapy.
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