Incidental thyroid C cell hyperplasia: clinical significance and implications in practice

Medullary Thyroid Carcinoma in a Patient with MEN 1 Syndrome. Case Report and Literature Review

Medullary thyroid cancer (MTC) is typically associated with multiple endocrine neoplasia type 2 syndrome (MEN 2), but not with multiple endocrine neoplasia type 1 (MEN 1). We report a very rare case of MTC in a patient with MEN 1 syndrome. A 60-year-old Caucasian woman with sporadic MEN 1 syndrome was admitted in October 2018 for recurrent hyperparathyroidism unresponsive to medical therapy. Her medical history included the diagnosis of a non-functioning pancreatic neuroendocrine tumor (NF-pNET) of the head of the pancreas 1.5 cm in size in 2001, and subtotal parathyroidectomy for uncontrolled hyperparathyroidism due to bilateral parathyroid hyperplasia in the same year. This history prompted genetic studies, and MEN 1 syndrome was confirmed. Family screening was performed in first-degree relatives, with negative results. Other typical clinical manifestations of MEN 1 syndrome were ruled out. In November 2018, the patient underwent excision of the residual left inferior parathyroid, extended to include the left thyroid lobe, for recurrent uncontrolled hyperparathyroidism. The pathologist identified MTC and adenoma of the parathyroid gland. Genetic tests were performed to identify any RET mutation, with negative results. The patient underwent total thyroidectomy about 6 months later, and the subsequent histological report showed only focal reactive C-cell hyperplasia of the thyroid. A literature review identified only three previously published cases of MTC coexisting with MEN 1 syndrome. This association may have two etiological hypotheses: either a sporadic MTC arising in a patient with MEN 1 syndrome, or a rare case of medullary cancer linked to a MEN 1 gene mutation.

Reactive C cell hyperplasia as an incidental finding after thyroidectomy for papillary carcinoma

The biologic and clinical significance of reactive C cell hyperplasia (CCH), adjacent to differentiated thyroid cancers, remains unknown. Our aim was to investigate the presence of CCH in thyroidectomy specimens with papillary thyroid carcinomas (PTC) and discuss its epidemiology and histology. In total, 413 patients were prospectively included in the study (189 benign goiters, 224 PTC). Reactive CCH was observed in 9.8% of PTC cases (32% males, 68% females, mean age 48.3 ± 16.4 years) and usually ipsilateral to the primary tumor (91%). Histologically, CCH was either focal (91%) or diffuse (9%) and almost always (92%) found in the middle or upper thirds of the thyroid lobes. Patients with PTC/CCH were generally younger than patients with benign goiters (0.027). On the other hand, patients with PTC and with PTC/CCH did not differ in terms of age, gender, basal calcitonin levels, primary tumor size, multifocality, extrathyroidal invasion, or lymph node metastasis. Thyroiditis, however, was more frequent in cases with PTC/CCH compared to PTC alone. Reactive CCH is considered a physiological response of the C cells to various stimuli, differentiated thyroid cancer among others. It bears no malignant potential and requires no additional treatment, following thyroidectomy.