[983] Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Kidney: A Clinicopathologic Study of 23 Cases

Paari Murugan, Pheroze Tamboli, Bogdan Czerniak, Charles C Guo. University of Texas MD Anderson Cancer Center, Houston, TX

Background: Primary Ewing sarcoma/primitive neuroectodermal tumor (PNET) of the kidney is a rare neoplasm. There has been limited clinicopathologic data on this distinct tumor.
Design: We retrospectively searched our pathology database from 1995 to 2010 and found 23 cases of Ewing sarcoma/PNET of the kidney. No patient had history of Ewing sarcoma/PNET elsewhere in the body. The pathology specimens included resections (n=21) and biopsies (n=2), and the histologic slides were reviewed for pathologic analysis. Clinical information was collected from patients' medical records.
Results: The patients included 13 male and 10 female with a mean age of 31 years (range, 8-70 years). The most common presenting symptoms were flank pain (n = 13) and hematuria (n = 8). The average tumor size was 11.7 cm (range 5-20 cm). Grossly, the tumors were usually solid with focal cystic, necrotic, and hemorrhagic changes. Microscopic analysis showed a predominantly lobular growth pattern (n = 14), with focal papillary (n = 3), alveolar (n = 1), and hemangiopericytoma-like (n = 1) patterns. Most tumors (n = 11) showed robust mitotic activity with mitotic figures of >10/10 high-power fields. Necrosis (n = 13) and lymphovascular invasion (n = 14) were common. Homer Wright rosettes (n = 6) and perivascular pseudorosettes (n = 1) were also identified. The tumors invaded the renal sinus or perinephric fat (n = 11), renal vein (n = 13), and adrenal gland (n = 2). Immunohistochemical analysis showed that tumor cells were positive for CD99 (21/23), vimentin (7/8), neuron-specific enolase (6/6), synaptophysin (5/13), and CD56 (3/7) and negative for cytokeratin (0/16) and desmin (0/9). Molecular and fluorescence in situ hybridization analysis showed rearrangement of the EWSR1 gene (10/10), which was associated with EWSR1-FLI1 gene fusion (7/10). Follow-up information was available for 18 patients. All 18 patients had metastasis, commonly in the lungs (n = 12), bone (n = 6), lymph nodes (n = 4), and liver (n = 2). Twelve patients died from the disease in a mean of 21 months after diagnosis; 6 patients were alive at a mean of 49 months after diagnosis.
Conclusions: Primary Ewing sarcoma/PNET of the kidney occurs in patients of a wide age range. Tumors usually present in an advanced stage with extrarenal spread and metastasis. Although primary Ewing sarcoma/PNET of the kidney shares histologic, immunohistochemical, and molecular features with its counterpart in the bone and soft tissue, Ewing sarcoma/PNET of the kidney appears to be a more aggressive tumor with a poorer clinical outcome.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 147, Monday Morning


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