Use of Immunohistochemical Markers (HNF-1β, Napsin A, ER, CTH, and ASS1) to Distinguish Endometrial Clear Cell Carcinoma From Its Morphologic Mimics Including Arias-Stella Reaction

In this study, classic CC immunohistochemical markers (Napsin A, HNF-1β, and ER) and 2 recent novel markers, cystathionine gamma-lyase (CTH) and arginosuccinate synthase (ASS1), are assessed for their utility in distinguishing CC from its morphologic mimics. Tissue microarrays containing 64 CC, 128 EC, 5 EC with clear cell change, 16 SC, 5 mixed carcinomas, and 11 whole ASR sections were stained, with 12 additional examples of ASR stained subsequently. A cutoff of 70% and moderate intensity were used for HNF-1β, 80% of cells and strong intensity were used for CTH, and any staining was considered positive for the remaining markers. For differentiating CC from pure EC and SC, HNF-1β, Napsin A, and CTH all performed well. HNF-1β had higher specificity (99.3% vs. 95.1%) but lower sensitivity (55.8% vs. 73.1%) compared with Napsin A. CTH did not substantially outperform HNF- 1β or Napsin A (sensitivity 51.9%, specificity 99.3%). ASS1 and ER were not helpful (specificities of 60.1% and 22.6%). For differentiating CC from ASR, HNF-1β, Napsin A, and CTH stained a large proportion of ASR and were not useful. However, ER positivity and ASS1 negativity were helpful for identifying ASR (specificity 88.2% and 95.1%, respectively). EC with clear cell changes exhibited immunohistochemical patterns similar to pure EC (HNF-1β−, ER+, and CTH−). No markers were useful in confirming the CC components in mixed carcinomas.
Source: International Journal of Gynecological Pathology - Category: Pathology Tags: PATHOLOGY OF THE CORPUS: ORIGINAL ARTICLES Source Type: research