Introduction/Background Signet-ring stromal tumor is a rare ovarian stromal neoplasm characterized by a population of bland signet-ring cells, devoid of mucin or lipid, in a generally cellular fibromatous stroma.

The presence of signet-ring cells in ovarian tissue is classically described as histological marker of Krukemberg tumor, which is a highly aggressive metastatic adenocarcinoma, with poor survival. In opposition, ovarian fibroid is a usually benign stromal tumor.

Methodology We report on a case of signet-ring stromal tumor of the left ovary in a 16-year-old woman, who attended the gynecology department, referred from primary care due to primary amenorrhea.

No diseases, or allergies. No prior surgical Interventions.

Does sports 3 times/week. No anosmia.

Gynecological history Primary amenorrhea.

Denies sexual intercourse

Normal hormonal profile (FSH 6.1, LH 2.4, Estradiol 68, normal TSH and PRL)

Results Exploration:

Weight 49kg. Size 170cm

Normal external genitalia with intact hymen. Developed secondary sexual characters.

Supplementary tests -Transrectal US: 42 x 22 mm retroverted uterus with 4.7 mm homogeneous endometrium. Left ovary with a solid cystic formation of 76x59x86 with peripheral vascularization and a larger cystic zone of 63x39mm without papillae at its lower pole. Healthy ovarian tissue is not visible. RO 23mm regular . No free fluid is observed

-Negative tumor markers (including HCG and AFP)

-Normal XX karyotype

Conclusion Signet-ring tumor of the ovary is a rare variant of benign ovarian stromal neoplasm and should be distinguished from metastatic mucin-secreting signet-ring adenocarcinoma.

The clinical history, operative finding, and histological examination should be considered as elements for the differential diagnosis.

In difficult cases, immunocytochemistry provides improved diagnostic accuracy in distinguishing signet ring stromal cell tumor and its mimics from Krukemberg tumor. The panel of histochemical techniques should include PAS, mucicarmine, and Alcian Blue. In addition to epithelial immunohistochemical markers such as EMA and pancytokeratin and stromal markers such as vimentin and calretinin.

Diagnosis Left adnexal tumor of 9 cm. 16 years

Given this diagnosis, exploratory laporoscopy is considered with probable left adnexectomy

Treatment Laparoscopic left oophorectomy is performed with the following intraoperative findings:

-Uterus and right adnexal normal.

Solid-cystic smooth-walled tumor free in Douglas dependent on the left ovary of about 8–9 cm. Left fallopian tube normal.

Pathology report -Left ovary:

ovarian fibroma with signet ring stromal cells

IHC study Calretinin, S100, CK AE1/AE3, PAS, ALCIAN BLUE, CD10 negative, Ki67<5%

-PAAF OI : negative for malignant cells

Differential Diagnosis The anatomopathological report points to an ovarian stromal tumor with signet ring cells and not to a metastatic lesion by Krukemberg by IHC (except for negativity of calretinin).

However, digestive pathology screening is requested with normal gastroscopy, colonoscopy and CT AP

Close follow-up is considered due to risk of recurrence