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Clinical Imaging
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CLINICAL IMAGING
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Suprarenal retroperitoneal liposarcoma with intracaval tumor thrombus: an imaging mimic of adrenocortical carcinoma
Zsoka Vajtai ª, Elena Korngold ª, Jody E. Hooper b, Brett C. Sheppard ℃, Bryan R. Foster ª, Fergus V. Coakley a,*
a Department of Diagnostic Radiology, Oregon Health and Science University, Portland, OR 97239
b Department of Pathology, Oregon Health and Science University, Portland, OR 97239
” Department of Surgery, Oregon Health and Science University, Portland, OR 97239
ARTICLE INFO
Article history: Received 8 April 2013 Received in revised form 11 July 2013 Accepted 23 August 2013
Keywords:
Retroperitoneal liposarcoma Adrenocortical carcinoma PET/CT
ABSTRACT
We report a 57-year-old previously healthy man who presented with dull right upper quadrant pain, weight loss, fatigue, and night sweats. Computed tomography demonstrated a large, heterogeneously enhancing, soft tissue mass with no macroscopic fat above the right kidney with tumor thrombus extending into the inferior vena cava and right atrium. Positron Emission Tomography scanning demonstrated intense Fluorodeox- yglucose avidity in the primary tumor and tumor thrombus. The presumptive radiological diagnosis was adrenocortical carcinoma, but surgical pathology revealed a dedifferentiated liposarcoma. We conclude that suprarenal retroperitoneal liposarcoma should be included in the differential diagnosis for an apparent adrenal mass with venous invasion.
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1. Introduction
Intravenous tumor extension is a well-known feature of adreno- cortical carcinoma, occurring in approximately one third of cases [1], and accordingly, adrenocortical carcinoma is generally the primary diagnostic consideration for an adrenal mass with intravenous tumor thrombus seen at imaging. We recently encountered a patient in whom a right-sided suprarenal retroperitoneal liposarcoma with intracaval tumor thrombus mimicked an adrenocortical carcinoma at imaging. The purpose of this case presentation is to present the computed tomography (CT) and Positron Emission Tomography (PET) findings in this case so that the differential diagnosis for an apparent adrenal mass with venous invasion can be broadened to include retroperitoneal liposarcoma.
2. Case description
A 57-year-old previously healthy man presented with dull right upper quadrant pain, weight loss, fatigue, and night sweats. Contrast- enhanced CT demonstrated a large, heterogeneously enhancing, soft tissue mass with no macroscopic fat content above the right kidney. The right adrenal gland was not visible separately from the mass. Tumor thrombus extended into the inferior vena cava and right atrium (Fig. 1). PET/CT scanning demonstrated intense Fluorodeox- yglucose (FDG) avidity in the primary tumor and in the tumor
thrombus with standard uptake value of 21.2 (Fig. 2). No distant metastases were identified. The presumptive radiological diagnosis was adrenocortical carcinoma. En bloc surgical resection of the tumor was performed and entailed right adrenalectomy, right nephrectomy, resection of portion of the inferior vena cava, and a Segment 8 liver resection. Extension of tumor thrombus into the heart was removed by open atriotomy with the patient on cardiopulmonary bypass. Grossly, the surgical resection specimen consisted of a 16.5-cm heterogeneous tan-red to yellow mass with areas of necrosis, surrounding but distinct from the remnant adrenal gland and adherent to the superior portion of the kidney. The mass was also adherent to the undersurface of the liver, which necessitated a resection of hepatic Segment 8. Microscopically, the mass showed focal areas of adipose tissue with adipocytes of varying size and dark, atypical vacuolated nuclei, consistent with well-differentiated lipo- sarcoma. The majority of the tumor demonstrated increased cellular- ity with severe nuclear atypia, consistent with dedifferentiated liposarcoma. Invasion into large veins was present. Segment 8 of the liver showed a 2-cm nodule of adherent dedifferentiated liposarcoma. The final histopathological diagnosis was primary retroperitoneal dedifferentiated liposarcoma (Fig. 3). Tumor recurred in the inferior vena cava and right atrium 4 months after surgery, and the patient died of his disease within 6 months of initial diagnosis.
3. Discussion
Most suprarenal masses with intravenous tumor thrombus are adrenocortical carcinomas. Other adrenal tumors that have
* Corresponding author. Oregon Health and Science University, Portland, OR 97239. Tel .: +1 503 494 2333; fax: + 1 503 494 4982. E-mail address: coakleyf@ohsu.edu (F.V. Coakley).
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occasionally been reported to invade the inferior vena cava include metastases from hepatocellular carcinoma [2,3], metastases from lung cancer [4,5], pheochromocytoma [6,7], and primary leiomyosarcoma of the adrenal gland [8]. We believe that this is the first report of a suprarenal primary retroperitoneal liposarcoma invading the inferior vena cava and mimicking an adrenocortical carcinoma.
Liposarcoma is the most common primary retroperitoneal malig- nancy and is classified by the World Health Organization as well- differentiated, myxoid, round cell, pleomorphic, or dedifferentiated [8]. The imaging appearance of retroperitoneal liposarcoma varies with subtype, such that well-differentiated liposarcoma often con- tains radiologically evident macroscopic fat while dedifferentiated liposarcoma may appear as a heterogeneous soft tissue mass with no radiologically visible macroscopic fat content [9]. In a series of 45 patients with dedifferentiated retroperitoneal liposarcoma, the average macroscopic fat content at CT ranged from 25% to a little over 50% [10]. While retroperitoneal liposarcoma are typically large at presentation, adjacent organ invasion is rare and usually seen in higher grade tumors [11,12]. Invasion of the inferior vena cava occurred in only 2 of 39 patients (5%) with retroperitoneal liposarcoma, one with dedifferentiated and one with round cell subtype. Our case is unusual in that the adrenal gland was engulfed in the mass, precluding preoperative identification of the mass as being
of retroperitoneal rather than adrenal origin, and no macroscopic fat was radiologically detectable in the mass, which might have helped suggest a diagnosis other than adrenocortical carcinoma. Complete absence of macroscopic fat in dedifferentiated liposarcoma is unusual but recognized [10]. The PET/CT findings in our case were helpful in confirming the malignant nature of the mass and intracaval extension but did not contribute to the differential diagnosis because both retroperitoneal liposarcoma and adrenocortical carcinoma are FDG avid with intensity of FDG uptake shown to be related to patient prognosis for both tumors [13,14]. While sarcoma is known to have a predilection for venous invasion, the mechanism of tumor thrombus development is unknown. More generally, venous tumor thrombus is regarded as a form of metastatic spread, and portal venous invasion by hepatocellular carcinoma has been associated with overexpression of MicroRNA-135a [15].
In conclusion, suprarenal retroperitoneal liposarcoma with intra- caval tumor thrombus may mimic adrenocortical carcinoma at imaging and should be included in the differential diagnosis for an apparent adrenal mass with venous invasion. This consideration could be clinically important because neoadjuvant chemotherapy has potential utility in the setting of retroperitoneal sarcoma but not for adrenocortical carcinoma [16].
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