Primary Thyroid Lymphoma : An Uncommon Etiology of Compressive Goiter

Abstract

Primary thyroid non-Hodgkin's lymphoma is a rare entity. It is defined as a lymphoma occurring in the thyroid gland with or without the involvement of regional lymph nodes. Diffuse large B-cell lymphoma is the predominant subtype, followed by the extranodal marginal zone B-cell lymphoma of MALT, mantle cell lymphoma, SLL, and follicular lymphoma. Hashimoto's thyroiditis is considering as a causal factor. Diffuse large B-cell lymphoma and mantle cell lymphoma are known by an aggressive course while MALT lymphoma and small lymphocytic lymphoma (SLL) are characterized by an indolent clinical course. The most common clinical presentation is an enlarging painless neck mass, growing rapidly and causing an obstruction of the upper airway. Differential diagnosis is an anaplastic carcinoma, squamous cell carcinoma, metastasis of unknown primary and thyroiditis. The sensitivity and the specificity of the FNAC can be increased if consolidated by the use of the flow cytometry, the immunohistochemistry (IHC) and PCR.Three modalities of treatment could be proposed: surgery, radiotherapy, and chemotherapy-dependent on the histologic subtype.