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Microcystic stromal tumors (MCSTs) of the ovary are rare sex cord-stromal tumors that are considered benign neoplasms because almost all cases display unilateral, localized lesions and have benign outcomes, except for one recurrent case with familial adenomatous polyposis and another initial metastatic case with a CTNNB1 mutation. We report herein a sporadic case that relapsed as intra-abdominal spread 9 years and 1 month after primary left salpingo-oophorectomy for torsion of the ovarian tumor pedicle. The tumor relapsed as multiple disseminations at the subabdominal wall, Douglas pouch, and omentum. Histologically, the tumor cells formed microcysts and infiltrated the surrounding adipose tissue, similar to the invasive implants of ovarian epithelial borderline tumors. Mutation analysis of the recurrent tumor revealed a somatic CTNNB1 p.S33Y activated missense mutation and a germline KDR p.Q472H variant. In conclusion, long-term clinical follow-up may be needed to detect any recurrence of MCST, irrespective of familial adenomatous polyposis.

This study aimed to clarify the genetic features of endometrioid-type endometrial cancer arising in adenomyosis (EC-AIA) using targeted sequencing and immunohistochemistry (IHC) for both carcinoma and adjacent adenomyosis tissues. We identified three endometrioid-type EC-AIAs in 689 patients with endometrial cancer; two exhibited grade 3 endometrioid carcinoma. IHC revealed retained expression of PMS2, MSH6, ARID1A, and PAX2. Two of them showed diffuse strong p53 expression only in the carcinoma. PTEN expression was lost in carcinoma of only one of these cases. Carcinoma had many gene mutations than adjacent adenomyosis in all cases. KRAS and TP53 mutations were found in two of them. The other patient had mutations in KRAS, PIK3CA, and PPP2R1A. They were classified as two "p53-mutated" and one "non-specific molecular profile." These molecular alterations in endometrioid-type EC-AIA imply similar carcinogenesis to a subset of endometrial endometrioid carcinoma and might be used as targets of liquid biopsy after further validation.

Gastric-type adenocarcinoma (GAS) of the cervix is a human papilloma virus (HPV)–independent, aggressive, and chemo-resistant adenocarcinoma. However, although the histopathological features of GAS have been extensively investigated, squamous differentiation has not been mentioned. This study aimed to elucidate the frequency of GAS with squamous differentiation and describe their clinicopathological characteristics. We retrospectively evaluated 78 patients with GAS (n = 13) and adenosquamous carcinoma (n = 65) diagnosed between 2000 and 2020. Two patients with GAS with squamous differentiation were identified. Both tumors showed advanced stage (pT2bN1) and had predominant GAS and merged squamous cell carcinoma components without p16-block positivity and HPV DNA. Gastric-type adenocarcinoma in situ was confirmed in both cases. Some cases of GAS could show squamous differentiation mimicking the usual, HPV-associated, adenosquamous carcinoma. GAS with squamous differentiation is recognized as an HPV-independent cancer.