Cytomorphologic features of metastatic endometrioid carcinoma by fine needle aspiration

Background: Although metastatic disease is commonly seen in high grade carcinomas of gynecologic origin, it also occurs in low to intermediate grade endometrioid carcinomas (LGEMCAs), and may even be the primary presentation of disease. Tissue confirmation is necessary to guide therapy, but performing biopsies might not always be feasible or practical. In such instances, fine needle aspiration (FNA) is a safe and efficient alternative. No comprehensive series describing the cytomorphologic features of metastatic LGEMCA on FNA samples has been published. This study describes clinical and cytomorphologic features of metastatic LGEMCA diagnosed by FNA. Methods: The pathology archives at 2 academic institutions were searched for patients with endometrial or ovarian endometrioid carcinoma, with concurrent or subsequent sampling of metastatic sites by FNA. Results: Twelve cases were identified; all slides were reviewed and cytomorphologic features recorded. Four cases were obtained from metastatic sites as primary presentation of disease, and 8 cases were obtained from metastatic sites in patients with known history of LGEMCA. Metastatic LGEMCAs generate cellular specimens composed of cohesive clusters of cells with areas of gland formation. Consistent cytomorphologic features included nuclear overlapping, low to intermediate nuclear to cytoplasmic ratios, round to elongated nuclear shape, finely vacuolated cytoplasm, mild to moderate nuclear membrane irregularities, squamous metaplasia, and inconspicuous nucleoli. Variability was seen with regards to the presence of necrosis (50% of cases) and mitosis (25% of cases). Conclusion: The presence of these features on FNA samples should raise concern for an underlying gynecologic malignancy.