Use of Marrow Scintigraphy to Confirm Compensatory Marrow Rather than Active Myeloma

We read with much interest the article entitled “Use of marrow scintigraphy to confirm compensatory marrow rather than active myeloma” by Bartel et al. published in your esteemed journal. This article enlightens us regarding a very interesting case of false positive fluorodeoxyglucose (FDG) uptake in a follow‐up case of multiple myeloma (MM). The authors in the present case have very nicely described the role of sulfur colloid bone marrow scintigraphy to differentiate reactive bone marrow from active disease. In MM, 18F FDG-positron emission tomography/computed tomography (PET/CT) can scan the whole body in reasonable time frame and in a single scan which can detect focal and diffuse bone marrow involvement with high sensitivity and specificity. However, as 18F‐FDG is a nonspecific radiotracer which is taken up by any metabolically active tissue, it is not specific for disease detection. False-positive PET/CT scans may also occur in settings of negative bone marrow and negative M-component markers and these conditions include inflammatory conditions, chemotherapy (within 1 month), or radiation therapy (within 2–3 months).[1] 99Technitium sestamibi (methoxy-isobutyl-isonitrile [MIBI]) imaging using Tc-99m-2-MIBI, is an alternative nuclear imaging modality to identify areas of active disease in MM, not only morphological disease activity but also functional disease activity which may be of use in assessing response to treatment. It is better than PET/ CT in identifying diffuse disease involving spine and pelvis.[2] Somatostatin receptor scintigraphy using 111In-pentetreotide can also be a good alternative to find the malignant plasma cells in MM and plasmacytoma patients, especially at relapse.[3] MM is a process characterized by neoplastic proliferation of plasma cells, and these cells nearly always produce complete monoclonal immunoglobulins or monoclonal immunoglobulin light chains. On the basis of increased methionine uptake in plasma cells, active MM can also be imaged with 11C-methionine PET.[4] 99mTc-sestamibi has also been proposed as a potential tracer in patients with MM. The presence of focal uptake or of intense diffuse bone marrow uptake suggests that the patient has active and advanced stage disease while a negative scan in a patient with MM clearly indicates remission.