Clear-cell adenocarcinoma of the female genital tract: presence of hyaline stroma and tigroid background in various types of cytologic specimens.

Hyaline basement membrane-like stromal material and tigroid background are distinctive cytologic features observed in Diff-Quik (DQ)- or Giemsa-stained smears of clear-cell adenocarcinoma (CCA) of the female genital tract. However, it is uncertain how often these features are present in different types of cytologic specimens, and which type of preparation is optimal for this diagnosis. We therefore reviewed the cytologic features of CCA in three types of specimens, including 15 scrape cytology specimens, 7 fine-needle aspiration (FNA) specimens, and 15 peritoneal cytology specimens, with emphasis on the features observed in DQ-stained smears. The cell morphology in scrape cytology specimens and FNA specimens was comparable, whereas in peritoneal cytology specimens, the cytoplasm was better preserved. Most tumor cells had fragile cytoplasm containing variable amounts of fine vacuoles, and round nuclei with distinct or prominent nucleoli. Hyaline stroma was present in 93% of scrape cytology specimens, 71% of FNA specimens, and 80% of peritoneal cytology specimens. Tigroid background was observed in 47% of scrape cytology specimens, 43% of FNA specimens, but in none of the peritoneal cytology specimens. Formation of a tigroid background may be prevented by the abundant fluid content in peritoneal cytology specimens. Hyaline stroma and tigroid background were uncommonly seen in scrape smears from other types of primary ovarian tumors, mainly juvenile granulosa cell tumor and yolk sac tumor. However, the additional presence of papillary structures allows CCA to be readily distinguished from these other tumors. We propose that scrape cytology offers the best approach for the intraoperative cytologic diagnosis of CCA.