Clinicopathologic characteristics and prognostic factors of sarcomatoid renal cell carcinoma

We seek to summarize the clinicopathologic characteristics and prognostic factors of sarcomatoid renal cell carcinoma (SRCC), an uncommon type of renal cell carcinoma.

Between 2004 and 2012, 23 patients with SRCC were treated at a large urology center in south central China. We collect patient's clinicopathologic features from medical records to assess diagnosis, prognostic factors and efficacy of systemic therapy. Clinical data were absent in 3 cases, and 20 patients were enrolled in the final study.

Immunohistochemically, almost all SRCC expressed cytokeratin (91%), epithelial membrane antigen (87%) and vimentin (100%). Sarcomatoid differentiation occurs in various kinds of subtypes of RCC with almost the same probability. The median tumor size was 10.5 cm. The CT findings of these tumors revealed low-density (n = 5; 25%) or mixed (n = 15; 75%) masses with necrotic areas and often showed an infiltrative morphology (n = 15; 75%). All 20 cases demonstrated heterogeneous enhancement, and eleven (55%) cases demonstrated >50% necrosis. Six cases complicated with calculus and hydronephrosis. Sixteen (80%) patients demonstrated invasions of tissues localized in Gerota's fascia, and 8 (40%) tumors invaded beyond Gerota's fascia. Fifteen (75%) patients demonstrated lymph node metastasis, and sixteen (80%) patients had distant metastasis. Five patients received systemic therapy, and one patient given high-dose interferon-α had a completely response, and one patient received chemotherapy based on gemcitabine had partial response. The median overall survival of all patients was 5.8 months. Patients without distant metastasis had a median overall survival of 35 months compared with 3 months of those with distant metastasis (P < 0.002). The percentage of the sarcomatoid components did not have an obvious influence to the prognosis (P = 0.197).

Heterogeneity, hugeness, infiltration and necrosis are typical image features of SRCC. The prognosis of SRCC is poor and clinic stage especially the existence of distant disease is the important factor influencing prognosis.