Rare Ovarian Carcinoid Tumors Show Favorable Outlook in Seven-Case Analysis

A new retrospective analysis from Shandong Medical and Pharmaceutical University Hospital, published in Diagnostic Pathology, examines seven cases diagnosed at the institution between 2014 and 2023, systematically documenting their clinical presentation, microscopic morphology, immunohistochemical profile, treatment, and follow-up outcomes.

The study team, led by Jing Qi and colleagues, collected clinical data and pathology records for all seven patients and reviewed the relevant literature. Their goal was to better define the clinicopathological characteristics of a neoplasm so uncommon that individual centers rarely accumulate enough cases to draw meaningful conclusions.

Histological classification revealed that insular carcinoid was the most common subtype, accounting for five of the seven cases, or 71.4 percent. Four of the tumors were associated with ovarian cystic teratoma, a well-recognized context in which these neuroendocrine tumors arise.

Immunohistochemical staining showed positive reactivity for neuroendocrine markers in all cases, confirming the neuroendocrine nature of the tumors. The Ki-67 proliferation index, a measure of cellular growth activity, was low in six cases, at 3 percent or below, with a range of less than 1 percent to 3 percent. One case, identified as case 5, showed a slightly higher index of 5 percent together with cellular atypia, marking it as the most proliferatively active tumor in the cohort.

Treatment and follow-up data carried the most reassuring message of the study. No tumor recurrence or metastasis was observed during postoperative follow-up in any of the seven patients. All patients in the series were diagnosed at stage I, and all remained disease-free during the follow-up period.

The authors conclude that primary ovarian carcinoid is a rare ovarian tumor that often lacks specific clinical symptoms and is frequently accompanied by cystic teratoma. In their experience, the prognosis is generally favorable after surgical resection, a finding they note is consistent with the favorable outcomes reported in the broader literature.

The rarity of the tumor presents a persistent challenge for clinicians.

The study’s authors are careful to frame their conclusions within the limits of the sample. With only seven cases, all diagnosed at stage I, the series cannot assess how clinical stage, histological type, or proliferative activity influence long-term outcomes. The researchers explicitly state that further studies with larger cohorts are needed to evaluate these factors, and the single case with a higher Ki-67 index and cellular atypia illustrates the kind of variation that larger datasets will need to address.

For now, the analysis adds a carefully documented set of seven cases to the limited published record of primary ovarian carcinoid, confirming low proliferative activity, frequent association with teratoma, and disease-free follow-up in this small cohort, while underscoring how much remains to be learned about this uncommon neoplasm.

Subject of Research: Clinicopathological features and prognosis of primary ovarian carcinoid tumors in a seven-case retrospective series

Article Title: Primary ovarian carcinoid: a clinicopathological analysis of 7 cases

Article References: Qi, J., Zhang, K., Li, H., Wang, N., & Yu, N. (2026). Primary ovarian carcinoid: a clinicopathological analysis of 7 cases. Diagnostic Pathology. https://doi.org/10.1186/s13000-026-01860-1

Image Credits: AI Generated

DOI: 10.1186/s13000-026-01860-1

Keywords: primary ovarian carcinoid, ovarian tumor, neuroendocrine tumor, insular carcinoid, cystic teratoma, Ki-67 index, immunohistochemistry, surgical resection, prognosis, Diagnostic Pathology, retrospective study, stage I