Metastatic Lung Adenocarcinoma With Occult Involvement of Gluteal Muscles as the Sole Site of Distant Metastases

Lung cancer metastases to soft tissues are rarely reported in the literature. In this report, we discuss a case of a 59-year-old female who presented with worsening shortness of breath for over five months. A CT scan of the chest revealed right upper lobe mass and ipsilateral mediastinal adenopathy. An endo-bronchial ultrasound (EBUS)-guided biopsy of the involved lymph nodes revealed cellular features consistent with lung adenocarcinoma. MRI of the brain was negative for metastases; however, a positron emission testing (PET) scan showed fluorodeoxyglucose (FDG)-avid nodules in the soft tissues of the bilateral buttocks. Tissue biopsy of the buttock lesions confirmed metastases of lung origin. To the best of our knowledge, this is the first case report of metastatic lung adenocarcinoma with occult involvement of the gluteal muscles as the sole site of distant metastasis.