Diagnostic Tissue Re-Evaluation Supporting the Observation of a ¹¹C-Methionine PET-Negative Residual Paraskeletal Mass in Multiple Myeloma
Abstract
A 52-year-old man with Bence Jones protein λ-type multiple myeloma developed a large sacral bone-associated, paraskeletal mass. After radiotherapy and idecabtagene vicleucel, serum and urine immunofixation tests were negative, marrow minimal residual disease assessment was negative, and post-treatment 11C-methionine positron emission tomography/computed tomography showed no abnormal uptake in the residual lesion, although computed tomography showed a persistent mass. A re-biopsy was not clinically justified in this case. A re-evaluation of the diagnostic tissue revealed plasma cell-rich areas and acellular collagen-rich stroma with extracellular matrix-associated proteins and λ light chain-derived peptides. Observation was selected, and the mass gradually decreased without any clinical relapse.
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BibTeX
@article{kakiuchi2026diagnostic,
title = {{Diagnostic Tissue Re-Evaluation Supporting the Observation of a ¹¹C-Methionine PET-Negative Residual Paraskeletal Mass in Multiple Myeloma}},
author = {Seiji Kakiuchi and Chiharu Mishima and Kanae Yamakawa and Naru Tomigaki and Akimasa Sakamoto and Shutaro Fujioka and Isamu Harima and Hiroaki Akiyama and Ryotaro Niwa and Ikumi Takagi and Yoko Kozuki and Yoshiharu Miyata and Nobuko Iwata and Kyoko Yoshihara and Satoshi Yoshihara and Kyoko Otani},
journal = {Internal Medicine},
year = {2026},
month = aug,
doi = {10.2169/internalmedicine.7907-26},
url = {https://www.jstage.jst.go.jp/article/internalmedicine/advpub/0/advpub_7907-26/_article},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Diagnostic Tissue Re-Evaluation Supporting the Observation of a ¹¹C-Methionine PET-Negative Residual Paraskeletal Mass in Multiple Myeloma
AU - Seiji Kakiuchi
AU - Chiharu Mishima
AU - Kanae Yamakawa
AU - Naru Tomigaki
AU - Akimasa Sakamoto
AU - Shutaro Fujioka
AU - Isamu Harima
AU - Hiroaki Akiyama
AU - Ryotaro Niwa
AU - Ikumi Takagi
AU - Yoko Kozuki
AU - Yoshiharu Miyata
AU - Nobuko Iwata
AU - Kyoko Yoshihara
AU - Satoshi Yoshihara
AU - Kyoko Otani
PY - 2026
DA - 2026/08/19
JO - Internal Medicine
DO - 10.2169/internalmedicine.7907-26
UR - https://www.jstage.jst.go.jp/article/internalmedicine/advpub/0/advpub_7907-26/_article
AB - A 52-year-old man with Bence Jones protein λ-type multiple myeloma developed a large sacral bone-associated, paraskeletal mass. After radiotherapy and idecabtagene vicleucel, serum and urine immunofixation tests were negative, marrow minimal residual disease assessment was negative, and post-treatment 11C-methionine positron emission tomography/computed tomography showed no abnormal uptake in the residual lesion, although computed tomography showed a persistent mass. A re-biopsy was not clinically justified in this case. A re-evaluation of the diagnostic tissue revealed plasma cell-rich areas and acellular collagen-rich stroma with extracellular matrix-associated proteins and λ light chain-derived peptides. Observation was selected, and the mass gradually decreased without any clinical relapse.
SN - 1349-7235
SN - 0918-2918
ER -