J Breast Cancer.  2013 Mar;16(1):117-121.

Skeletal Muscle Metastases from Breast Cancer: Two Case Reports

• Kim YW
• Seo KJ
• Lee SL
• Kwon KW
• Hur J
• An HJ
• Ko YH
• Kim JS
• Won HS

Abstract

The skeletal muscle is an unusual site for metastasis from breast cancer. We present two cases of breast cancer that relapsed as skeletal muscle metastasis without other distant organ metastasis. We performed the core needle biopsy of metastatic sites and confirmed discordance in estrogen receptor, progesterone receptors, and human epidermal growth factor receptor 2 expression between primary breast cancer and skeletal muscle metastases. In the second case, we found the skeletal muscle metastasis through F-18 fluorodeoxyglucose positron emission tomography/computed tomography scans (PET/CT). Intramuscular hot spots on PET/CT scans should be considered as a sign of metastasis even in the absence of abnormalities on computed tomography scans. Our patients received systemic chemotherapy, and showed a partial response. Further studies are needed to determine the prognosis and proper management of isolated skeletal muscle metastasis in breast cancer.

Keyword

Breast; Carcinoma; Neoplasm metastasis; Skeletal muscle

MeSH Terms

Biopsy, Large-Core Needle
Breast
Breast Neoplasms
Electrons
Estrogens
Humans
Muscle, Skeletal
Neoplasm Metastasis
Prognosis
Receptor, Epidermal Growth Factor
Receptor, erbB-2
Receptors, Progesterone
Estrogens
Receptor, Epidermal Growth Factor
Receptor, erbB-2
Receptors, Progesterone

Figure

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  Figure 1 (A) Computed tomography scan of the abdomen, showing soft tissue density lesions in rectus abdominis muscle. (B) F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography, showing abdominal muscle mass with increased FDG uptake (SUVmax, 7.1).

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  Figure 2 Diffuse scattered neoplastic cells with distraction of muscle fascicles. (A) Abdominal muscle mass (H&E stain, ×400). (B) Gluteal muscle mass (H&E stain, ×400).

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  Figure 3 (A) F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography, showing right gluteal muscle mass with increased FDG uptake (SUVmax, 14.0). (B) Computed tomography scan of the abdomen, showing poorly-demarcated, round, isodense mass in right gluteal muscle.

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