Diagnostic clues for hyalinizing trabecular tumor on fine needle aspiration cytology.

Objectives: The hyalinizing trabecular tumor (HTT) is a rare benign neoplasm of the thyroid gland. This neoplasm has overlapping cytological features with Papillary Thyroid Carcinoma, Medullary Carcinoma and Follicular Neoplasm with Nuclear Features of Papillary Carcinoma. This can lead to misdiagnosis of malignancy in fine needle aspiration (FNA) cytology specimens with unnecessary total thyroidectomy. The aim of this study is to determine if there are some cytological features that could help us to suspect HTT on FNA specimens and avoid radical surgery. Material and Methods: With this purpose we have collected 6 cases diagnosed of HTT in Hospital Clínico San Carlos of Madrid (Spain) in the last 10 years and reviewed the cytological specimens. Result: We conclude that the presence of hyaline material in FNA specimens of HTT is a constant feature being a diagnostic clue. We must be cautious not to confuse it with dense colloid or amyloid material, the latter seen in Medullary Carcinoma. Papillary architecture and fibrovascular cores are not present in a HTT. Special stains as ki-67, calcitonin and Congo Red staining could help us in achieving the correct diagnosis. Conclusion: We feel the cytopathologists must be aware of the distinguishing features of this lesion, mainly the typical hyaline material to achieve a proper diagnosis and be able to reduce unnecessary aggressive management of these patients.

Neuroendocrine Neoplasms in Rare Locations: Clinicopathological Features and Review of the Literature.

INTRODUCTION: Neuroendocrine tumors (NETs) occur more often in lungs, gastrointestinal tract, or pancreas. Data about terminology and grading of NETs in rare locations are scarce and variable, and they have been reported mainly as case reports. MATERIALS AND METHODS: We here describe our experience with NETs in unusual locations. We have reviewed all NETs diagnosed in our institution and summarized their clinicopathological features. We have also reviewed the literature and discussed the main characteristics of NETs in each site. RESULTS: Two hundred and forty-three primary NETs were diagnosed. About 55.2% of patients were men and the mean age was 62 years. About 90.7% of NETs were located in lungs, gastrointestinal tract, or pancreas, and 50.8% of them were low-grade tumors. We identified 13 NETs in rare locations: breast, ovary, endometrium, vulva, uterine cervix, extrahepatic biliary tract, kidney, sinonasal tract, and thymus. Three additional tumors were diagnosed by the senior author in other institution. Patients were asymptomatic or presented with nonspecific symptoms. All NETs were treated with surgery and 31% of patients received adjuvant therapy. There were 10 Grade 3 (62.5%), 2 Grade 2 (12.5%), and 4 Grade 1 (25%) tumors. Mean follow-up was 72 months. About 60% of G3 tumors recurred or progressed. G2 tumors were located in breast, and both patients are stable. About 50% of G1 tumors recurred or progressed (both renal NETs). CONCLUSIONS: NETs in rare locations are heterogeneous, and their behavior does not seem to correlate absolutely with tumor grade. More studies are needed to clarify the role of proliferation rate in these tumors.