Atypical primary Burkitt lymphoma of the tyroid gland: a pratical approach for differential diagnosis and management

Primary thyroid lymphomas are rare diseases that continue to produce diagnostic and therapeutic dilemmas. Among these, Diffuse Large B-Cell Lymphoma (DLBCL) represents the more common subtype while Burkitt lymphoma (BL) is unusual. Distinguishing between BL and DLBCL is critical as the two disease require different therapeutic management. Diagnostic accuracy is therefore essential to obtain patient safety. Here, we described the second case of Burkitt Lymphoma of the thyroid gland reported in the English literature, investigate the differential diagnosis and explore the diagnostic approach that might be used when neoplasia with morphological features intermediate between BL and DLBCL happens on pathologist’s practice. A 56-year-old women presented to our attention for the evaluation of a rapidly growing neck mass causing compressive symptoms. Ultrasound examination demonstrated two hypoechogenic nodules within a diffusely enlarged thyroid gland. Histological analysis showed cells resembling DLBCL, as well as starry sky pattern and immunohistochemical pattern suggestive of BL. The final diagnosis of BL was confirmed by FISH analysis that demonstrated c-myc-IgH rearrangement with t(8;14) translocation. This study demonstrates that no single parameter alone (such as morphology, genetics analysis or immunophenotyping) can be used as gold standard for the diagnosis of BL, but a combination of several diagnostic techniques is necessary for an optimal practical approach. Since treatment regimens for BL and DLBCL differ significantly, we believe that our study should be useful to suggest the correct diagnostic algorithm to be used when a case of BL, with unusual localization and ambiguous morphological features, is encountered in routine setting.