[1194] Endometrial Clear Cell Carcinoma: Incidence and Clinicopathologic Features

Gloria H Lewis, Ann K Folkins, Christina S Kong, Richard L Kempson, Teri A Longacre. Stanford University, Stanford, CA

Background: The clinicopathologic features of endometrial clear cell carcinoma (CCC) are poorly described, in part due to the poor reproducibility of the diagnosis amongst experienced gynecologic pathologists.
Design: All cases of EC with “clear cell” in the diagnostic line were identified in archival files from 2001-0212. Four gynecologic pathologists (median post-training years: 17) independently classified the cases as pure CCC, CCC mimic favor endometrioid (ME), CCC mimic favor serous (MS), or unknown (U). IHC for ER, p53, p16, HNF1-β, and WT1 was performed on all cases.
Results: There were a total of 852 endometrial carcinomas and 15 with “clear cell” in the diagnostic line. All had tumor cells with clear cytoplasm. The 4 gynecologic pathologists' diagnoses and IHC results are in Table 1.

Table 1
1234ERp53p16HNF
CCCMEMEU--, 5%--
MEMEMEME3+, >95%3+, 90%--
CCCCCCCCCCCC--, 0%2+, 10%1+, 10%
MEMEMEME3+, 90%-, 0%2+, <1%-
UUUU3+, 60%3+, 80%2+, 80%-
UUUU-3+, 80%2+, 80%-
MEMEUME3+, 50%-, 0%2+, 90%-
MEMEUME-3+ 90%-1+, 80%
UUCCCMS-3+, >95%2-3+, 80%1+, 70%
UUCCCCCC3+, 80%-, <5%-2+, 90%
CCCCCCCCCCCC-3+, 90%2-3+, 50%1+, 80%
UUUME--, 0%-1+, 20%
UUUME2+, 60%3+, 30%2-3+, 50%2+, >95%
CCCCCCCCCCCC2-3+, 90%-, <5%1+, 50%2+, 90%
UUCCCCCC1+, 5%1+, 10%1+, 5%1+, 50%
1-4 refer to GP

There were only 3 confirmed CCC: each had hyalinized stroma, non-stratified epithelium, papillary or glandular architecture, abundant clear cytoplasm, and enlarged, centrally located, angulated nuclei. Figure 1 depicts the 3 CCC (A-C); 1 ME (D) and 1 U agreed upon by all 4 gynecologic pathologists (E) and 1 discrepant case (1 CCC, 2 ME, 1 U, panel F). The specificity of HNF1-β for CCC was 58%, with positive predictive value (PPV) of 0.46%. All were WT1-negative.


Conclusions: Endometrial CCC is extremely rare. The IHC phenotype of CCC appears to be ER-negative (2/3), WT1-negative (3/3), p53-negative (2/3), p16-patchy (3/3), and HNF1-β -positive (3/3), but data are limited. HNF1-β is not specific, and has a very low PPV (0.46%).
Category: Gynecologic & Obstetrics

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 114, Tuesday Morning

 

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