Thyroid low‐grade B‐cell lymphoma (MALT type) with extreme plasmacytic differentiation: Report of a case diagnosed by fine‐needle aspiration and flow cytometric study

Abstract

We describe a case of thyroid marginal-zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) with extreme plasmacytic differentiation in an 80-year-old woman who had presented with a rapidly growing thyroid swelling. The diagnosis was initially suspected on fine-needle aspiration (FNA) and subsequently confirmed by flow cytometric analysis of the aspirated material. The smears revealed features of Hashimoto's thyroiditis admixed with large numbers of atypical large plasmacytoid lymphoid cells accompanied by variable numbers of small lymphocytes and mature plasma cells. The differential diagnosis of a predominantly plasmacytic smears on FNA of the thyroid is discussed herein, with emphasis on the role of immunophenotypic studies to exclude or confirm the diagnosis of lymphoma.

Utilility of flow cytometry as ancillary study to improve the cytologic diagnosis of thyroid lymphomas

“…To our knowledge, only few articles have reported the systematic use of FC in detecting TL (11,(19)(20)(21)(22). In this study, FC was utilized together with FNAC to improve the detection of lymphomas among lymphoid infiltration of the thyroid.…”

Cytological Findings for the Diagnosis of Primary Thyroid Mucosa-Associated Lymphoid Tissue Lymphoma by Fine Needle Aspiration

“…However, some of those studies [8,9,10,11,12,17,22,23,24,25,26,27,29,30] did not include any cases of MALT lymphoma, while those that did [7,13,14,15,16,17,18,19,28,31] only examined a few cases. For this reason, we considered the present conditions for cellular analysis based on the concept of MALT lymphoma to be insufficiently accurate.…”

“…FNAC of thyroid primary malignant lymphoma is useful as a preoperative qualitative diagnostic procedure, and previous studies have attempted to improve the diagnostic accuracy of FNAC [6,7,8,9,10,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28,29,30,31]. However, some of those studies [8,9,10,11,12,17,22,23,24,25,26,27,29,30] did not include any cases of MALT lymphoma, while those that did [7,13,14,15,16,17,18,19,28,31] only examined a few cases.…”

“…However, the diagnosis of lymphoma has been considered more appropriate than plasmacytoma when lymphocytes and PC in the lesion are CD20 positive [3]. Among cytological studies [7,19,22,23,24,25,26,27,28,29,30,31] regarding plasmacytoma or MALT-EPCD of the thyroid gland, prior to the publication of the WHO classification in 2001, immunohistochemical classification is discussed in only 1 article [27], and there are only few studies [7,19,28,29,30,31] on cytology based on the WHO classification [2,3]. Therefore, more data should be collected to discriminate MALT-EPCD from extramedullary plasmacytoma.…”

Marginal zone B cell lymphomas with extensive plasmacytic differentiation are neoplasms of precursor plasma cells

“…Occasionally MZL demonstrate extensive plasmacytic differentiation (P-MZL). These tumors are similar to or may be identical with primary extra-osseous plasmacytomas (EP) (1,3,(7)(8)(9)(10)(11)(12)(13).…”