[736] Invasive Urothelial Carcinoma with Chordoid Features: A Clinicopathologic Study of 12 Cases

RM Cox, AG Schneider, AR Sangoi, WJ Clingan, N Gokden, JK McKenney. UAMS, Little Rock, AR; Stanford University, Stanford, CA

Background: Variant forms of urothelial carcinoma are well-described. We have recently encountered urothelial carcinomas with a unique chordoid morphology characterized by extensive myxoid stromal change and cellular cording, which to our knowledge, has not been described previously.
Design: 12 urothelial carcinomas with myxoid stroma and cellular cording were identified. The patient age, patient sex, tumor stage, association with typical urothelial carcinoma, and clinical outcome were recorded. Immunostains for CK20, CK34BE12, p63, calponin, GFAP, S-100 protein, oncofetal protein glycipan-3, and brachyury were performed in 7 cases with available blocks.
Results: 11 of 166 (7%) consecutive invasive urothelial carcinomas had foci with chordoid morphology, and 1 consult case was added (n=12). The patients' ages ranged from 50 to 85 (mean: 68) years; 8 were male and 4 were female. 7 had cystectomies, 4 transurethral resections, and 1 nephroureterectomy. Morphologically, each case had at least focal areas (range 5-95%) with chordoid morphology. When well-developed, the neoplastic cells had scant eosinophilic cytoplasm and were arranged into cords closely mimicking chordoma, extraskeletal myxoid chondrosarcoma, myoepithelioma, or yolk sac tumor. No sarcomatoid component, no intracytoplasmic mucin, and no glandular formation were present in any case. All 12 cases had foci of typical urothelial carcinoma present at least focally. Immunophenotypically, 7 of 7 cases showed immunoreactivity for p63 (nuclear) and cytokeratin 34BE12 (cytoplasmic). S-100 protein showed only focal cytoplasmic staining in 1 of 7 cases. Immunostains for CK20, calponin, GFAP, oncofetal protein glypican-3, and brachyury were negative in the 7 cases studied. 11 of 12 cases were high stage (pT4: 5, pT3: 4, pT2: 2, and pT1: 1). 6 of the 8 cases (75%) with nodal sampling had metastatic disease. In 1 case, the lymph node metastasis had areas with chordoid morphology. 9 of 12 patients had available follow-up: 2 died of disease (1 and 10 months), 4 alive with disease (2-8 months), 3 NED (2-108 months).
Conclusions: Urothelial carcinomas can show an unusual chordoid morphology mimicking other myxoid neoplasms, but they maintain an immunophenotype typical of high grade urothelial carcinoma. Foci of typical urothelial carcinoma were present, facilitating the diagnosis, but the chordoid component may comprise the majority of the tumor and may be present in metastatic foci.
Category: Genitourinary (including renal tumors)

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 117, Monday Morning