Burkitt-like lymphoma infiltrating a hyperfunctioning thyroid adenoma and presenting as a hot nodule.

BACKGROUND

Most solitary hyperfunctiong regions on thyroid scan consist of benign tissue. Here we report a patient with a Burkitt-like lymphoma that was infilterated into a region containing a hyperfunctioning nodule.

SUMMARY

A 56-year-old man was referred to our Endocrine Unit in May 2009 due to the incidental discovery of a large left thyroid lobe nodule by a computed tomography study. This had been performed to search for a primitive tumor in a patient with bone metastasis. He was clinically and biochemically thyrotoxic with no evidence of humoral thyroid autoimmunity. The nodule had a dyshomogenous appearance at neck ultrasonography, with multiple hypoechogenic areas and calcifications. (99m)-Technetium thyroid scintiscan revealed a hot nodule with suppression of the contralateral lobe. Fine-needle aspiration cytology indicated the presence of neoplastic cells not of thyroid origin. Remission of hyperthyroidism was obtained with methimazole, and the patient was submitted to left lobe thyroidectomy and istmectomy. Histological analysis of the surgical specimen led to a diagnosis of Burkitt-like large B-cell lymphoma harbored within a thyroid adenoma. After further staging, the final diagnosis was stage IV E Burkitt-like lymphoma with the involvement of the bone and the thyroid. This is the first description of an aggressive Burkitt-like lymphoma that infiltrated an hyperfunctioning thyroid adenoma, thus presenting as a hot nodule at thyroid scintiscan. In our patient there was no humoral or histological evidence of thyroid autoimmunity, thus suggesting a metastatic seeding of the lymphoma within the hyperfunctioning thyroid nodule.

CONCLUSIONS

Involvement of the thyroid gland by Burkitt-like lymphoma is extremely rare as is close localization of malignancy and a hyperfunctioning thyroid nodule. As highlighted by the present report, performing fine-needle aspiration cytology should be always considered in the clinical context of a metastatic disease of unknown origin or when there are ultrasonography signs suggesting malignancy, even when the nodule is hyperfunctioning.