A 65-year-old male with a history of transurethral resection (TUR) for bladder cancer of superficial transitional cells of high-grade sigmoid (pT1 G3), with subsequent recurrence of low-grade cardiomyopathy, who smoked the following pack:
Abdominal computed tomography (CT) without intravenous contrast (IV) was performed in the follow-up of her bladder neoplasm. The incidental finding was a heterogeneous nodular lesion with fat content (retroperitoneal hypodense edge) of 2 cm in diameter.
Abdominal ultrasound showed a retroperitonal hyperechoic lesion in contact with the right side of the inferior vena cava.
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Watchful waiting was decided and a control CT was performed one year later, showing growth of the mass (4 cm in maximum diameter) that displaces and compresses the inferior vena cava medially without showing signs of invasion.
Retroperitoneal liposarcoma was suspected. Magnetic resonance imaging (MRI) with gadolinium IV confirmed the fat content of the lesion and a discrete heterogeneous contrast uptake.
The T1 sequences showed a hyperintense lesion, although slightly lower than the retroperitoneal fat, subcutaneous mesentery, with a smaller area in the upper pole of the lesion.
The fat suppression technique showed a slight hyperintensity compared to the perilesional fat mainly in the upper half.
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In the images in the opposite phase, the lesion was hypointense, presenting a nodular zone in its upper pole of higher signal intensity and corresponding to the area of lower intensity in the T1 sequence and higher intensity in the fat suppression.
After gadolinium administration, a slight uptake was observed.
With the radiological diagnosis of fat tumor probably liposarcoma (due to its predominant frequency within the retroperitoneal masses), surgery was decided.
A reniform mass was surgically removed, posterior to the inferior vena cava and anchored retroperitoneum to the anterior vertebral ligament at 2 cm from the right renal vein at its lower edge.
Non vascular lesions show only small peripheral lymphatic vessels.
A 6 x 5 cm pseudoencapsulated lobular tumor of adipose consistency and grayish-yellow color was referred for pathological study.
Histology of the specimen reveals a well-defined adipose tumor, which shows extensive hematopoietic islots with the presence of the 3 series together with rounded lymphoid aggregates, pre-malignant myelolipoma diagnostic bone marrow.
This last possibility was ruled out by bone marrow analysis confirming the diagnosis of retroperitoneal extra-adrenal myelolipoma.
