Image of the Month—Quiz Case

A 55-year-old morbidly obese man presented with recurrent lower back pain. Imaging with computed tomography showed a 6 × 6-cm hypervascular mass at the aortic bifurcation, immediately anterior to the iliac arteries, with a central area of focal necrosis (Figure 1). There was no radiological evidence of pelvic lymphadenopathy. Results of urine chemistry studies revealed mildly elevated catecholamine levels, with a norepinephrine level of 89 μg/g of creatinine (reference range, 7-65 μg/g of creatinine) and epinephrine, dopamine, and creatinine levels all within normal limits. The patient denied any history of episodic hypertension, dizziness, palpitations, headaches, or diaphoresis. He also denied any recent fevers, night sweats, or chills and had no history of cancer or irradiation therapy.

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Figure 1. Computed tomographic imaging of a large mass at the aortic bifurcation. Notable features include hypervascularity, large diameter, and central area of necrosis.

The patient was taken to the operating room, and the tumor was removed with hand-assisted laparoscopy. The gross specimen appeared tan and red, with a thin capsule encasing the tumor in its entirety. Histological analysis revealed a “patternless pattern” of mesenchymal cells with a high degree of vascularity and strands of collagen deposition (Figure 2). Immunohistological staining of the tumor specimen was strongly positive for CD34 and bcl-2.

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Figure 2. Histological section of the tumor with a “patternless pattern” of mesenchymal spindle cells, abundant vascular structures, and a collagen matrix, all typical features of solitary fibrous tumor (hematoxylin-eosin, original magnification ×40).

A.  Paraganglioma (organ of Zuckerkandl)

B.  Lymphoma

C.  Retroperitoneal sarcoma

D.  Solitary fibrous tumor

Answer