Skeletal Muscle Metastases on FDG PET/CT Imaging

Abstract

Our study confirmed the rare occurrence of SMM. Furthermore, FDG PET/CT can potentially detect unsuspected SMM. Interestingly, in our patient population, lung cancer was found to be the most frequent malignancy metastasizing to the skeletal muscles. Knowledge about the presence and appearance of widespread SMM may aid in appropriate interpretation of FDG PET/CT scans.

Detection of skeletal muscle metastasis: torso FDG PET-CT versus contrast-enhanced chest or abdomen CT

“…This result is not inconsistent with previous imaging studies reporting the prevalence of SMM of various cancer types in the range of 0.2-1.6% with PET-CT or CT (4)(5)(6)14). SMM has long been considered as a very rare form of hematogenous metastasis in several CT and MRI studies (3,4,8,15).…”

“…The more routine application of PET-CT in cancer patients has resulted in the detection of more distant metastases, such as SMM, that can be missed using CT (7). Recently, there have been many case reports about SMM detected by PET-CT (10-12) and a few comprehensive clinical studies (6,13). However, PET-CT and contrast-enhanced CT have not been directly compared regarding the detection of SMM.…”

“…The reported prevalence of skeletal muscle metastasis (SMM) among cancer patients varies, in the range of 0.03-17.5%, with a relatively higher prevalence of [6][7][8][9][10][11][12][13][14][15][16][17].5% in autopsy studies (2,3) compared to 0.03-5.6% in clinical imaging-based studies (4)(5)(6), indicating that more sensitive imaging modalities are required to detect SMM (7).…”

The Rare Isolated Solitary Muscle Metastasis of Breast Carcinoma Confirmed by 18F-FDG PET/CT

“…The muscular system is relatively resistant to metastatic disease. The factors for resistance are muscle movement causing mechanical tumor destruction, muscle pH, tumor removal ability of lactic acid production associated with muscle angiogenesis, the activation of lymphocytes, and natural killer cells in the muscular system [6][7]. However, in large autopsy series it is more evident than in the subclinical muscle metastases; incidence varies between 0.2% and 17.5% [7][8].…”

Detection of multiple muscle involvement in eosinophilic myositis with 18F-FDG PET/CT

“…FDG uptake in skeletal muscles can occur in a variety of conditions, such as primary malignancy [1], metastasis [2], inflammatory myopathies [3] and other physiological states [4]. Eosinophilic myositis is a rare inflammatory condition of skeletal muscle which can clinically mimic soft tissue sarcoma or metastasis [5].…”