Histological classification of mucinous ovarian tumors: inter-observer reproducibility, clinical relevance, and role of genetic biomarkers.

The morphological distinction between the various types of mucinous ovarian tumors has major prognostic implications but may be challenging. The aims of our study were to describe inter-observer reproducibility in the morphological diagnosis of mucinous ovarian tumors, to evaluate the clinical relevance of possible diagnostic discrepancies, and to identify molecular abnormalities correlated with the histological type. Seventy-nine ovarian mucinous borderline tumors (MOB) and either expansile or infiltrative carcinomas (MOC) were independently reviewed by two gynecological pathologists. Molecular analysis was performed in 32 cases. Concordance between the two pathologists was reached in 67 cases (k: 0.78). The main discrepancies (8/12) were the evaluation of nuclear grade 3 or that of microfoci (< 5 mm) of infiltrative-type carcinoma in an otherwise typical expansile MOC. Our follow-up analysis showed that infiltrative MOC had a lower overall survival (OS) (p < 0.0024) and progression-free survival (PFS) (p = 0.0060) as compared with MOB and expansile MOC. The presence of nuclear grade 3 or microfoci (< 5 mm) of infiltrative-type pattern of invasion in an otherwise typical expansile MOC did not alter the prognosis as compared with expansile MOC without these features, in terms of OS (p < 0.0028) and PFS (p = 0.0074). KRAS mutations were more frequent in MOB (71%), than in expansile (50%) and infiltrative MOC (14%). In contrast, the prevalence of TP53 mutation was lower in MOB (43%), than in expansile (58%) and infiltrative MOC (71%). Our results confirm that in MOC, the expansile pattern of invasion is associated with a better prognosis than extensive (> 5 mm) infiltrative-type pattern of invasion. No specific or sensitive molecular profile might help in the differential diagnosis of mucinous ovarian tumors.

Colon Cancer Metastasis Within a NIFTP: A Case Report and Review of the Literature.

The thyroid is an unusual site for metastasis, and metastases in a preexisting primary thyroid tumor are exceedingly rare. We report the first case of a patient with colon cancer who was diagnosed with a thyroid metastasis in a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). A 55-year-old male patient presented with a 19 mm thyroid nodule in the inferior left lobe. It was EU-TIRADS 5 on echography and suspicious of papillary thyroid carcinoma (Bethesda V) on cytology. Macroscopically, the nodule was fleshy and completely encapsulated. At frozen section examination, it demonstrated follicular architecture with mild atypia. Inside the nodule was a focus of tumor with glandular architecture, marked cellular atypia, and necrosis. These findings suggested a secondary malignancy. The patient's medical history was significant for metastatic colon cancer. The definitive histology showed features of metastatic colorectal adenocarcinoma within a NIFTP. Immunohistochemical studies were confirmatory with expression of CDX2 and CK20 localized to the metastatic focus. PAX8, TG, and TTF were negative in the metastasis but expressed in the surrounding NIFTP lesion. The possibility of a metastasis to the thyroid may be considered in patients presenting with a solitary thyroid nodule with a previous history of cancer. Metastatic colorectal adenocarcinoma occurring in a NIFTP has never been reported before now, although metastases to the thyroid are documented in the literature. In cases of a secondary malignancy to the thyroid, treatment is controversial.