RESUMEN
Summary: Large-cell neuroendocrine carcinoma (LCNEC) is a rare neuroendocrine prostatic malignancy. It usually arises after androgen deprivation therapy (ADT), while de novo cases are even more infrequent, with only six cases described. The patient was a 78-year-old man with no history of ADT who presented with cervical lymphadenopathy. Diagnostic approaches included PET/CT, MRI, CT scans, ultrasonography, biopsies, and cytological and immunohistochemical evaluations. Results showed a poorly differentiated carcinoma in the thyroid gland accompanied by cervical lymph node enlargement. Thyroid surgery revealed LCNEC metastasis to the thyroid gland. Additional metastases were identified in both the adrenal glands. Despite appropriate treatment, the patient died of the disease. De novo LCNEC of the prostate is a rare, highly aggressive tumor with a poor prognosis. It is resistant to most therapeutic agents, has a high metastatic potential, and is usually diagnosed at an advanced stage. Further studies are required to characterize this tumor. Learning points: De novo LCNECs of the prostate gland can metastasize almost anywhere in the body, including the thyroid and adrenal glands. LCNECs of the prostate are usually associated with androgen-depriving therapy, but de novo cases are also notable and should be accounted for. Further studies are required to fully understand and treat LCNECs more effectively.
RESUMEN
Differentiated thyroid cancer (DTC) represents the vast majority of all thyroid cancers, with the papillary variant being the most common. According to the previous 2009 American Thyroid Association (ATA) guidelines, papillary thyroid microcarcinoma (PTMC; ≤1 cm in diameter) exhibiting cervical lymph node metastasis corresponded to an intermediate-risk group for recurrence or metastasis. However, the latest 2015 ATA guidelines advocate that a patient with PTMC is low-risk if there are ≤5 regional node micrometastases. This means that therapeutic radioactive iodine (RAI) is not required. The current study reports a rare case of a patient who underwent total thyroidectomy due to multi-nodular goiter where the pathologic specimen exhibited two PTMC foci in regional lymph nodes, but no primary cancer was identified in the thyroid despite thorough examination of the thyroid parenchyma. The etiology of such results is unknown and it was hypothesized that it may be the consequence of insufficient pathologic examination or due to the regression of a primary PTMC in the thyroid. Moreover, the risk-stratification of cases with intra-lymph node PTMC without any evidence of primary cancer in the thyroid is not considered in the ATA recommendations. The aim of the current report was to elucidate the risk-stratification of this rare occurrence and to reconsider the possible etiologies. By extrapolating the latest ATA recommendations concerning a patient with a known primary PTMC and ≤5 metastatic micro-foci (thus the only difference between cases being the absence of a primary tumor), it was concluded that the patient should be considered low-risk. As a consequence, RAI therapy should be deemed as unnecessary despite the presence of lymph node microfoci. Moreover, it was proposed that cervical lymph node PTMC with no evidence of a primary tumor in the thyroid could be the consequence of normal thyroid tissue micro-deposit progression to cancer within the lymph node, which is a rare benign entity.