Small bowel metastasis from pulmonary rhabdomyosarcoma causing intussusception: a case report

BACKGROUND: Rhabdomyosarcoma (RMS), especially primary pulmonary RMS, is an extremely rare type of soft tissue sarcoma in adults. Small bowel is an uncommon site for metastases. CASE PRESENTATION: This report described an unusual case of jejunum metastasis from primary pulmonary RMS causing intussusception in a 75-year-old man. The patient consulted for 2 weeks of continuous dyspnea. Chest computed tomography (CT) demonstrated a large mass involving the left lower lobe. Transthoracic biopsy confirmed the existence of pleomorphic RMS. Immunohistochemical studies showed positive findings about desmin and MyoD1. The results of gastroscopy, colonoscopy and abdominal CT were all negative. Positron emission tomography/CT demonstrated a fluorodeoxyglucose-reactive large lesion in the left lower lobe without metastatic lesions. The patient received synchronous chemoradiotherapy. After 9 months, the patient presented with intermittent upper abdominal pain with nausea and vomiting. CT showed small bowel dilatation secondary to intussusception. The patient subsequently received laparotomy, and the intussuscepted small bowel segment was resected. Histological examination revealed pleomorphic RMS involving the mucosa, submucosa, and muscular tissues. CONCLUSIONS: RMS is highly aggressive and metastatic. The metastatic disease can rapidly progress to cause subsequent complications. The possibility of small bowel metastasis should be considered, although it is extremely rare.