A 35-year-old man was referred to the urology clinic by his primary care physician for consultation regarding bilateral, multifocal renal masses. The patient reported a 3-month history of intermittent right flank pain and chronic right flank soreness not associated with nausea, vomiting, fevers, or chills. He denied any urinary complaints or hematuria. Physical examination was largely unremarkable, except for facial angiofibromas; urinalysis revealed no blood or infection. Postvoid residual urine volume per bladder scan was 26 mL. Vital signs were within normal limits. The patient denied any tobacco or alcohol abuse. He did have a known history of tuberous sclerosis complex, and had undergone resection of several brain tumors (giant cell astrocytomas) as a child.
Laboratory values, including results of a complete blood cell count with differential, liver function tests, coagulation panel, and basic chemistry panel, were unremarkable. A CT scan of the abdomen and pelvis with IV contrast was obtained, and it showed bilateral, multifocal, lipid-rich renal masses, possibly consistent with angiomyolipomas (Figure 1). On cross-sectional imaging, the largest renal mass on the right side measured 3.7 × 4.1 cm, and the largest renal mass on the left side measured 3.1 × 3.6 cm. Multiple smaller renal masses were present bilaterally throughout the parenchyma of both kidneys, ranging in size from 0.8 × 0.4 cm to 1.2 × 1.1 cm.
The patient underwent CT-guided needle biopsy of one of the renal masses for definitive diagnosis and to rule out a lipid-rich renal cell carcinoma with macroscopic fat due to osseous metaplasia. Microscopic examination of the tissue by the pathologist revealed mixed uniform spindle and adipose cells in the presence of small vascular channels (Figure 2A). Immunoperoxidase staining was positive for melanocyte antigen recognized by T cells–1 (MART1) (Figure 2B); and for alpha-smooth muscle actin (Figure 2C), which confirmed the smooth muscle origin of the spindle cells. This histopathology was consistent with a diagnosis of renal angiomyolipoma.
Which of the following is the recommended initial treatment strategy for this patient?
A. Observation only
B.Treatment with an mTOR inhibitor
C. Angiography and embolization
D. Partial nephrectomy
E. Total nephrectomy
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