Impact of Fluoro-Choline PET/CT in Reduction in Failed Parathyroid Localization in Primary Hyperparathyroidism.

INTRODUCTION: Accurate localization of the pathological parathyroid gland is a prerequisite for minimally invasive surgical management of hyperparathyroidism (HPT). Poor imaging or discordance in odd situations like ectopic adenomas, parathyroid hyperplasia, syndromic HPT results in localization dilemma thus causing failed parathyroidectomy. We studied the impact of Fluoro-Choline (FCH) PET/CT imaging in reduction in localization failure of parathyroid adenoma. MATERIALS AND METHODS: We did a retrospective observational study (2018-2021) of HPT among which 97 patients underwent focused parathyroidectomy (FP). All patients had undergone ultrasound imaging and 99mTc-sestaMIBI scan with early SPECT/CT (MIBI). When this preliminary imaging was doubtful or negative or multiple lesions were expected, FCH PET/CT was performed. We compared the localization accuracy of MIBI scan and FCH PET/CT with surgical outcomes as reference standard. RESULTS: MIBI scan showed overall lesion detection rate (LDR) of 88.65% in localization of pathological parathyroid gland in 97 patients. The addition of FCH PET/CT improved the overall lesion detection to 97.9%. The overall possible localization failure was reduced from 11.34 to 2.06% with the addition of FCH PET/CT (p < 0.05). Out of 97 patients of FP, 87 patients showed features of parathyroid adenoma. Single hyperplastic gland was seen in 7 patients, lipoadenoma was seen in 1 patient and 1 patient had features suggestive of parathyroiditis on histopathology. FCH PET/CT was a useful adjunct and showed significant reduction in localization failure of parathyroid adenoma.

Amphicrine Medullary Thyroid Carcinoma - a Case-Based Review Expanding on Its MUC Expression Profile.

Amphicrine phenotype in medullary thyroid carcinoma (MTC) is a rare phenomenon characterized by tumor cells that show both endocrine differentiation (calcitonin secretion) and exocrine differentiation (mucin production and secretion). Not much is known about the pathobiology of amphicrine MTCs. This report undertook a case-based review approach by discussing the cytological, histopathological, and ultrastructural features of this rare enigmatic entity, expanding on the radiological and novel MUC immunohistochemistry findings from a 28-year-old MEN2B syndrome patient with C cell hyperplasia and multifocal MTC with amphicrine features. The patient had widespread hematogenous metastases at presentation. MUC immunoexpression analysis revealed evidence of micro-lumina formation, and unique to-date unreported expression patterns of MUC1, MUC5AC, and MUC6 in an amphicrine subtype of MTC. Review of the literature identified five other MTC cases with well-documented amphicrine features. Of these six cases, two were associated with MEN2B syndrome, and four had metastatic disease. Follow-up was available in three patients, and two died of disease. Recognition of this rare subtype of MTC may be of clinical interest given their frequent link to MEN2B syndrome and biological aggressiveness.