Endocervical-like (Müllerian) mucinous borderline tumours of the ovary are frequently associated with the KRAS mutation.
OBJECTIVE
Clinicopathological aspects of the endocervical-like mucinous borderline tumour of the ovary (EMBT), including higher frequencies of bilaterality, endometriosis and hormone receptor reactivity, and often admixtures of various Müllerian-type epithelia, closely resembles endometrioid tumour more than mucinous borderline tumour of the intestinal type (IMBT). Thus, the aims of this study were to determine whether EMBT is really a subtype of mucinous borderline tumours, as shown in the current classification system, and to determine the best classification for EMBT.


RESULTS
The clinicopathological and immunohistochemical features of 17 EMBTs were analysed, including oestrogen receptor (ER), progesterone receptor (PR), PTEN, cytokeratins (CK) 7 and 20, and β-catenin. Additionally, mutational analyses of the KRAS (exon 1) and PTEN genes (all nine exons) were performed in all cases, and the results were compared with literature findings for IMBT and endometrioid tumours. Twelve patients (71%) were confirmed histologically to have endometriosis in one or both ovaries. In seven cases, gradual transitions from endometriotic foci to the EMBT were identified. Immunohistochemically, all cases were reactive for ER and PR, with no nuclear expression of β-catenin. CK7 positivity was strong in all patients, whereas there was no reactivity for CK20. PTEN reactivity was diffuse in the nuclei of epithelial and underlying stromal cells. Sixty-nine per cent showed KRAS mutations in exon 1 and codon 12, but no PTEN mutation was identified in any of the nine exons.


CONCLUSIONS
Our study suggests that EMBT has features of both mucinous and endometrioid tumours and is an additional tumour type arising in endometriosis. While clinicopathological features of EMBTs are closer to endometrioid tumours, they still have molecular characteristics closer to IMBTs.
Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center Seoul. krkim@amc.seoul.kr
Kyu-Rae
KR
Kim
Jene
J
Choi
Jeong-Eun
JE
Hwang
Young-Ae
YA
Baik
Jeong Yeon
JY
Shim
Yong Man
YM
Kim
Stanley J
SJ
Robboy
D000328:Adult; D004252:DNA Mutational Analysis; D004715:Endometriosis / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009154:Mutation; D009375:Neoplasms, Glandular and Epithelial / Q000145:classification* / Q000235:genetics* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000145:classification* / Q000235:genetics* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D020133:Reverse Transcriptase Polymerase Chain Reaction; D055815:Young Adult; D018631:ras Proteins / Q000235:genetics*
C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins