Primary thyroid T-lymphoblastic lymphoma: a case report and review of the literature.

Most thyroid lymphomas are B-lineage, and T-cell lymphomas are rare. Here, we report a case of primary T-cell lymphoblastic lymphoma (T-LBL) of the thyroid gland. A 15-year-old boy presented with a painless thyroid mass. Ultrasonographic examination revealed a hypoechoic thyroid nodule measuring 4.6 cm × 1.9 cm × 3.4 cm. The thyroid function and antibodies were normal. Hemithyroidectomy was performed. Intraoperative frozen section was suggestive of malignant lymphoma. Histological examination showed diffuse round to oval medium sized cells with high nuclear/cytoplasmic ratio, finely dispersed chromatin, scanty cytoplasm, and numerous mitoses. Immunohistochemical studies revealed malignant cells were positive for terminal deoxynucleotidyltransferase, CD5, CD7, CD8, CD10, CD45RO, CD99, CD79a, CD3, CD1a and Ki-67 (>40%) and negative for CD34, CD20, BCL6, CD23, BCL2, Pax5 and EBV. A diagnosis of thyroid T-LBL was made. The patient was treated by intensive chemotherapy followed by allogeneic hematopoietic stem cell transplantation and has been in event-free survival for 65 months. The patient was unique because no cases of thyroid T-LBL have been previously reported, to our knowledge. Moreover, intensive chemotherapy followed by alloHSCT might be one of the adoptive options in therapy for this aggressive disease.