PMC5457931_01
Representative computed tomography and positron emission tomography (PET) images. (A) Swollen lymph nodes were observed in the right axilla (arrows) and abdominal para-aortic region (arrowhead). (B) A PET scan showed a 20 mm-nodule in the right lobe of the thyroid with the uptake of fluorodeoxyglucose (FDG) (maximum standardized uptake value, 11.13 units). The swollen lymph nodes, including those shown in (A), did not show the significant uptake of FDG.
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It showed a 20-mm nodule in the right lobe of the thyroid, which showed the most significant uptake of FDG (maximum standardized uptake value, 11.13 units) (Fig. 1), and swelling of the bilateral axillary (maximum, 12 mm), inguinal (maximum, 10 mm), and the abdominal para-aortic lymph nodes, without the significant uptake of FDG.
The histology of the sigmoid colon biopsy specimens. (A) The infiltration of inflammatory cells (mostly plasma cells) was observed (arrows). Malignant findings were not indicated (Hematoxylin and Eosin staining, magnification x400). (B) Most of the plasma cells were positive for immunoglobulin light chain kappa (arrowheads) (In situ hybridization for immunoglobulin light chains; magnification: x400).
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Colonoscopy was performed because of the patient's chronic diarrhea and weight loss, which showed a normal appearance, although a mucosal biopsy of the colon revealed the infiltration of plasma cells (Fig. 2A). An in situ hybridization assay for immunoglobulin light chains showed a deviation in the kappa light chain (Fig. 2B), suggesting that these plasma cells were clonal and consistent with the M protein.
The bone marrow histology (clot section). (A) A bone marrow section revealed the infiltration of lymphocyte- and plasmacyte-like atypical cells of various sizes (Hematoxylin and Eosin staining; magnification: x400). (B) The tumor cells showed the restriction of the immunoglobulin light chain, with an elevated kappa/lambda ratio, consistent with the findings in sigmoid colon tissue (In situ hybridization for immunoglobulin light chains; magnification: x400).
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The in situ hybridization assay again showed immunoglobulin light chain restriction, with an elevated kappa/lambda ratio (Fig. 3).