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Year : 2022  |  Volume : 37  |  Issue : 2  |  Page : 192-193  

Polymicrobial pyomyositis in a patient with suspected myeloma on 18F-FDG PET-CT

1 Department of Nuclear Medicine and PET-CT, All India Institute of Medical Sciences, New Delhi, India
2 Department of Neurology, All India Institute of Medical Sciences, New Delhi, India

Date of Submission13-Aug-2021
Date of Decision14-Dec-2021
Date of Acceptance16-Dec-2021
Date of Web Publication08-Jul-2022

Correspondence Address:
Dr. Nishikant Avinash Damle
Department of Nuclear Medicine and PET-CT, All India Institutes of Medical Sciences, New Delhi - 110 029
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijnm.ijnm_130_21

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Pyomyositis is an infective involvement of systemic skeletal muscles. We discuss the case of 43-year-old male who presented with quadriparesis, anemia, and hypercalcemia, leading to suspicion of multiple myeloma, and on FDG PET-CT, incidentally, pyomyositis was found. FDG PET-CT thus helped in diagnosing an occult infection which helped in the treatment of the patient.

Keywords: FDG PET-CT, occult infection, pyomyositis

How to cite this article:
Kalra S, Damle NA, Gupta SD, Baghel V, Elavarasi A, Sathish P. Polymicrobial pyomyositis in a patient with suspected myeloma on 18F-FDG PET-CT. Indian J Nucl Med 2022;37:192-3

How to cite this URL:
Kalra S, Damle NA, Gupta SD, Baghel V, Elavarasi A, Sathish P. Polymicrobial pyomyositis in a patient with suspected myeloma on 18F-FDG PET-CT. Indian J Nucl Med [serial online] 2022 [cited 2022 Aug 11];37:192-3. Available from:

A 43-year-old bed-ridden man with known diabetes presented to us with acute-to-subacute-onset quadriparesis, following a prodrome of fever for 2–3 weeks. With these complaints, he was admitted to another hospital where he was treated with empirical antibiotics for his fever and was discharged. However, in view of no clinical improvement and severe bony tenderness and myalgia of the thighs, he presented to us for second opinion in a bed-ridden state. Examination was suboptimal in view of severe pain and tenderness all over the body and pressure sores. Baseline investigations showed anemia with elevated ESR, and renal function tests showed raised serum creatinine and raised serum calcium levels. CPK was within normal limits. In view of clinical presentation with fever prodrome, quadriparesis, bony pain, and tenderness and laboratories showing elevated serum creatinine with hypercalcemia, possibility of myeloma was suspected and further worked up. Serum free light chain assay showed elevated lambda, kappa chains with normal lambda: kappa ratio. Bone marrow aspirate and biopsy revealed 7% plasma cells. F-18 FDG PET-CT scan was ordered as a part of myeloma workup. Maximum intensity projection [Figure 1]a image of PET revealed heterogeneously increased metabolic activity in the bilateral thigh and gluteal and forearm region. CT [Figure 1]b and fused PET-CT [Figure 1]c of the thigh region in the axial view showed increased inter- and intra-muscular tracer uptake with air pockets and atrophy. PET-CT [Figure 1]d in the coronal view showed the same findings. Atrophy and hypodensity were seen in the gluteal muscles too on CT [Figure 1]e. In addition to muscular involvement, cortical break was seen in the right scapula, as seen in axial CT [Figure 1]f. Based on PET images, a differential of infective pathology of muscles, i.e., pyomyositis was concluded since muscular involvement in myeloma is a rare event and more diffuse in pattern.[1],[2] Culture from thigh aspirate confirmed the growth of methicillin-sensitive Staphylococcus aureus (MRSA), and PCR was positive for Mycobacterium tuberculosis. Antibiotic and antitubercular course were initiated accordingly. Magnetic resonance imaging (MRI) has been the investigation/imaging modality of choice in soft tissue infections. Previous reports in MRSA-pyomyositis have shown it to be multifocal, thus reducing the feasibility of MRI.[3],[4] However, unfortunately, the patient had progressed into multisystem sepsis, and despite vigorous intravenous antibiotic therapy, the patient succumbed to septic shock.
Figure 1: Depicting various skeletal muscle sites of heterogenous hypermetabolism as seen in MIP image (1a), in axial CT images along with muscular atrophy and air pockets (1b and 1e) and in PET-CT fused axial (1c) and coronal (1d) images. Additional lytic lesion noted in right scapula as seen in axial CT images (1f).

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Pyomyositis on FDG PET-CT has been documented in few case reports in the past.[3],[5] However, the usual presentation is of pyrexia of unknown origin. Due to likely concurrent neuropathy (LMN quadriparesis) and subsequent immobilization, prior antibiotic therapy, and afebrile status at admission, there was masking of underlying pyomyositis presentation. FDG PET-CT can successfully detect occult infections in such cases.

This case highlights the importance of FDG PET in detecting underlying occult infection as these are a common cause for mortality in myeloma. Although this patient was a suspected myeloma case, such detection is important in clinical practice as early institution of appropriate antimicrobial therapy is lifesaving. Had FDG PET/CT not been done in this case, pyomyositis would have probably gone undetected indefinitely.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Liang M, Su M, Wang R, Wang W, Fan C. Muscle involvement of multiple myeloma revealed by FDG PET/CT. Clin Nucl Med 2017;42:300-2.  Back to cited text no. 1
Özkan E, Araz M, Cengiz Seval G, Nak D, Beksaç M. A rare extramedullary presentation of multiple myeloma: Paraspinal muscle involvement revealed by FDG PET/CT. Turk J Haematol 2021;38:69-71.  Back to cited text no. 2
Gill H, Kwok H, To KK, Ho PL, Mak HK, Chim CS, et al. Positron emission tomography in the diagnosis of disseminated pyomyositis due to PVL-negative methicillin-resistant Staphylococcus aureus. QJM 2013;106:485-6.  Back to cited text no. 3
Turecki MB, Taljanovic MS, Stubbs AY, Graham AR, Holden DA, Hunter TB, et al. Imaging of musculoskeletal soft tissue infections. Skeletal Radiol 2009;39:957-71.  Back to cited text no. 4
Harisankar CN, Mittal BR, Kashyap R, Bhattacharya A, Singhi S. (18) F-FDG positron emission tomography in multifocal pyomyositis. World J Nucl Med 2012;11:22-3.  Back to cited text no. 5
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