Tumor trabecular hialinizante de tiroides: comunicación de un caso

Abstract

Abstract: 

Hyalinizing trabecular tumor (HTT) of the thyroid originates from the follicular cell and is a rare entity. It predominates in women at the age of 50 years. It owes its name to its histologic appearance, composed of preferentially elongated cells, arranged in trabeculae with dense intra- and intertrabecular hyaline material. In FNA (fine needle aspiration puncture) it is usually diagnosed as indeterminate or suspicious category according to the Bethesda system (TBS), since cytologically it resembles papillary or medullary carcinoma. The evolutive course is usually benign, but the 2017 WHO Classification considers it as borderline/precursor tumor, taking into account its potential for dissemination. The importance of a correct diagnosis lies in the conservative treatment for TTH.

Seventeen-year-old patient referred to the endocrinology service for polycystic ovary syndrome. Physical examination: thyroid nodule, ultrasonographically measuring 2x2x1.5 cm (TI-RADS 4a), was punctured. FNA was reported as category IV TBS, follicular neoplasm/suspected follicular neoplasm. Surgery was decided. Macroscopy: total thyroidectomy surgical specimen, right lobe measured 3x3x1.7 cm; left lobe 3x2x1.5 cm and isthmus. Capsule opaque and congestive. In the right lobe: solid whitish nodular lesion with well-defined borders measuring 2x2x1.5 cm. Rest of the parenchyma: normal appearance. Apart 3 lymph nodes and 2 fragments of parathyroid. It was processed and stained with the usual technique, then immunohistochemistry. Microscopy: the nodule showed a proliferation of follicular cells arranged in anastomosing trabeculae separated by a finely vascularized stroma, with a myxoid aspect in some areas and fibrosclerotic in others. The cells had fused nuclei with some nuclear clefts and ample eosinophilic cytoplasm, occasional mitosis figures. The capsule was complete and undamaged. The rest of the thyroid gland, lymph nodes and parathyroid: preserved. Immunohistochemistry positive for thyroglobulin, TTF-1 and CD56, negative for calcitonin, synaptophysin and chromogranin, Ki67: 3%. Therefore, the diagnosis was: hyalinizing trabecular tumor.

Although TTH has a low incidence, in the presence of a morphological aspect that suggests its diagnosis, it is necessary to differentiate it from entities such as papillary, follicular and medullary carcinomas, pathologies with a more aggressive course that require oncologic treatment. The therapeutic indication for TTH is lobectomy.