Diffuse large B cell lymphoma of thyroid as a masquerader of anaplastic carcinoma of thyroid, diagnosed by FNA : A case report

Abstract

BackgroundBoth thyroid lymphoma and anaplastic carcinoma of thyroid present with rapidly growing mass in eldery patients. Anaplastic carcinoma has high mortality rate and combination of surgery, radiation therapy and multidrug chemotherapy are the best chance for cure. Prognosis of thyroid lymphoma is excellent and chemotherapy for widespred lymphoms and radiotherapy with or without adjuvant chemotherapy for tumors localized to the gland, are the treatment of choice.Case reportThis article reports a 70 year old man presenting with diffuse neck swelling and hoarseness of few weeks duration. Fine needle aspiration was done and reported as anaplastic carcinoma of thyroid which thyroidectomy was planned. The slides were sent for second opinion. After review, with initial diagnosis of anaplastic carcinoma versus lymphoma, immunocytochemical study was performed. Smears were positive for B cell markers and negative for cytokeratin, so with the impression of diffuse large B cell lymphoma, the patient received two courses of chemotherapy by which the tumor disappeared during two weaks.ConclusionDespite previous reports, stating easy diagnosis of high-grade thyroid lymphoma on the grounds of cytomorphological features we like to emphasize, overlapping cytologic features of the curable high grade thyroid lymphoma form noncurable anaplastic thyroid carcinoma and usefulness of immunocytochemistry to differentiate these two disease.

Thyroid Lymphoma: Recent Advances in Diagnosis and Optimal Management Strategies

“…Focusing on IHC, the realization that PTLs are positive for leucocyte common antigen, MS4A1 (CD20), and light chain and negative for cytokeratins on immunohistochemical staining has already improved the sensitivity and specificity of FNAC [61]. A study by Ito et al identified increased expression of CDC25A and CDC25B, which have oncogenic potential, in 47% and 67% of thyroid lymphomas, respectively, using IHC [62].…”

PAX8 is expressed in anaplastic thyroid carcinoma diagnosed by fine-needle aspiration: a study of three cases with histological correlates

“…The expression of PAX8 has been studied in C-cell-derived neoplasms with variable results ranging from negativity to focal positivity (13,23,24,27). In doubtful cases, positivity for medullary cancer markers (calcitonin, synaptophysin and chromogranin) is diagnostic (28). High-grade lymphomas closely mimic ATCs on FNA (29).…”

Undifferentiated Malignant Neoplasm Involving Parotid and Thyroid: Sampling and PAX8 Cross-Reactivity Can Obscure the Diagnosis of Lymphoma

“…While a single cell, dispersed cytologic architectural pattern is typical of lymphoma, ATC cells can occur singly or in dyshesive groups or intermixed with areas of better-differentiated thyroid carcinoma. TL can also be pleomorphic with dispersed cells arranged into tissue fragments and may be indistinguishable from ATC by light microscopy [11]. While the cell block material did contain several cellular groups and single cells, the material was nonetheless quantitatively limited and ultimately did not lead to a specific diagnosis, similar to the experience of others reported in the literature [12].…”