Abstract
Background Soft-tissue metastasis (STM) is a relatively rare, but not exceptional, manifestation of lung cancer. Since the lesions of STM are usually asymptomatic, they are easy to miss during clinical evaluation. The aim of the study was to explore the incidence and characteristics of STM in lung cancer using fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT), and evaluate its effect on tumor staging and treatment. Methods We analyzed 4543 patients with lung cancer who underwent 18 F-FDG PET/CT in our hospital between January 2013 and September 2018. 85 were diagnosed with STM and included in the study group. Imaging characteristics, clinical symptoms, and survival time (from confirmed STM to death) were recorded for all study subjects. Results A total of 219 lesions were identified by 18 F-FDG PET/CT: 215 were detected by PET (maximum standardized uptake value = 6.12); 139 were detected by CT. Muscle STM were primarily found in the hip, upper limb muscle; whereas subcutaneous STM were mainly distributed in the chest and abdomen, back. In 68 patients (80%), STM were found incidentally during routine 18 F-FDG PET/CT staging. The lesions were symptomatic in 17 cases (20%); in 10 patients (11.8%) STM was the first manifestation. Other site metastases were detected in 79 patients (92.9%). Isolated STM were found in 6 patients (7.1%), whose tumor staging and treatment were affected by PET/CT findings. At the end of the follow-up period, 69 patients were dead (median survival time= 5.0 months) and 5 were lost to follow-up. Conclusions STM may be a sign of advanced stage and poor prognosis in lung cancer. 18 F-FDG PET/CT is highly valuable in the detection of STM, and can impact tumor staging and management of lung malignancies.
An Atypical Presentation of Soft Tissue Metastasis in a Patient With Lung Cancer