Obstet Gynecol Sci.  2016 Mar;59(2):157-162. 10.5468/ogs.2016.59.2.157.

Genetic analysis of ovarian microcystic stromal tumor

• Lee JH
• Kim HS
• Cho NH
• Lee JY
• Kim S
• Kim SW
• Kim YT
• Nam EJ

• KMID: 2159013
• DOI: http://doi.org/10.5468/ogs.2016.59.2.157

Abstract

Microcystic stromal tumor (MCST) of the ovary is a rare subtype of ovarian tumor first described in 2009. Although high nuclear expression of β-catenin and β-catenin gene (CTNNB1) mutation are related with ovarian MCST, the origin and genetic background of ovarian MCST remain unclear. In this study, two cases of ovarian MCST are presented. Microscopically, the tumors showed a microcystic pattern and regions with lobulated cellular masses with intervening hyalinized, fibrous stroma. Tumor cells of both cases were stained with CD10, vimentin, and Wilms tumor 1. Genetic analysis was performed and β-catenin gene (CTNNB1) mutation in exon 3 was detected in both cases. This is the first report in regards of detecting CTNNB1 mutation in ovarian MCST through the use of pyrosequencing (a novel sequencing technique).

Keyword

CTNNB1 mutation; Microcystic stromal tumor; Ovary; Pyrosequencing

MeSH Terms

Exons
Female
Hyalin
Ovary
Vimentin
Wilms Tumor
Vimentin

Figure

• 

  Fig. 1 (A) Computed tomography (CT) findings of case 1. An 18×12-cm-sized cystic mass with smooth outer wall with no definite solid portion, suggesting benign epithelial ovarian tumor. (B) CT findings of case 2 presents a 24-cm-sized solid and cystic left ovarian mass, suspicious for malignant epithelial tumor. No pathologically enlarged lymph node or seeding mass was observed in the imaging study. (C) Magnetic resonance imaging findings of case 2 suggests malignant epithelial tumor of ovary. (D-F) Positron emission tomography-CT findings of case 2 shows intense uptake by a 24-cm-sized left ovarian mass and several lymph nodes in aortocaval space and left paraaortic space, which suggests ovarian malignancy with lymph node metastasis.

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  Fig. 2 Gross (A,B) and microscopic (C-F) findings. (A) Case 1. Fragmented specimen shows an admixture of gray-to-yellow, viable tumor tissues and red-to-tan, necrotic and hemorrhagic tissues. (B) Case 2. The resected specimen reveals a cystic mass displaying extensive internal tumor necrosis and hemorrhage. The cystic wall has multiple areas of irregular, nodular thickening, indicating viable tumor tissues. (C) Low-power view of case 1. Small, irregular, occasionally coalescing cystic spaces are lined by bland cells (H&E, ×100). (D) Low-power view of case 2. An area showing solid component exhibits similar nuclear features (H&E, ×40). (E,F) High-power views of (E) case 1 (H&E, ×400) and (F) case 2 demonstrate uniform, small, round to ovoid nuclei with absent or inconspicuous nucleoli. No mitotic activity is detected (H&E, ×200).

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  Fig. 3 Immunohistochemical findings (A,B) and pyrosequencing results (C,D). Immunostaining reveals the tumor cells are positive for (A) vimentin (immunohistochemistry; HRP-multimer method, ×200). (B) In addition, diffuse and strong nuclear immunoreactivity for β-catenin was identified, suggesting the nuclear translocation and accumulation of β-catenin protein in the individual tumor cells (immunohistochemistry; HRP-multimer method, ×400). (C,D) Pyrograms of a DNA sequence featuring a point mutation involving a single base pair substitution (c.98C>G; pS33C) in exon 3 of CTNNB1 gene. The mutated site is highlighted in blue and the allele frequencies are given in each table. (C) Case 1. (D) Case 2.

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