Activating BRAF Mutations Detected in Mixed Hürthle Cell Carcinoma and Multifocal Papillary Carcinoma of the Thyroid Gland: Report of an Unusual Case and Review of the Literature.

Despite the increase in the incidence of thyroid carcinomas, the occurrence of collision tumors in the thyroid remains a rare event. We present the case of a 69-year-old female who presented to the emergency department with a chief complaint of painful neck swelling. Imaging revealed a large right hemithyroid mass and a left hemithyroid nodule. Fine needle aspiration of the lesions and subsequent total thyroidectomy revealed a Hürthle cell carcinoma in the right lobe and bilateral multicentric papillary carcinoma foci, including 2 foci with a classical pattern and 1 encapsulated follicular variant in the isthmus. BRAF gene mutation analysis revealed V600E gene mutation in the classical variants of papillary carcinoma and in the Hürthle cell carcinoma. The focus of follicular variant of papillary carcinoma in the isthmus and a sample from normal thyroid tissue did not harbor BRAF mutations. This case is remarkable in being an unusual report of a follicular Hürthle cell carcinoma harboring the BRAF V600E mutation and occurring in collision with multifocal papillary carcinoma. Documentation of such cases is important as it helps better understand the pathogenesis, clinical behavior, and radiologic findings of such rare lesions and to determine the optimal treatment modalities.

An unusual case of autonomous hyperparathyroidism in a patient with X-linked hypophosphatemic rickets and Kallmann syndrome.

We are reporting an unusual patient who presented to our medical center at 18 years of age for evaluation of disabling bilateral lower extremity deformity and delayed puberty. Extensive clinical, laboratory, and radiologic evaluation confirmed the coexistence of 2 X-linked inherited disorders, X-linked hypophosphatemic rickets (XLH) and Kallmann syndrome (KS). Treatment with oral phosphate and calcitriol along with intramuscular testosterone injections was initiated. Despite a dramatic response, the course of treatment was complicated by secondary hyperparathyroidism and, 13 years later, by the development of an autonomous parathyroid adenoma that was surgically resected. Furthermore, the coexistence of XLH and KS has not been reported before. We believe that the proximity of the KAL-1 gene (Xp 22.3), involved in the pathogenesis of KS, to the phosphate regulating endopeptidase on the X chromosome gene (Xp 22.1-22.2), involved in XLH, might be responsible for this association.