Symptomatic involvement of the small bowel by metastasis from an extra-abdominal primary malignancy is rare, most commonly resulting from malignant melanoma and lung cancer; very rarely is small bowel involvement as first metastatic site. The Authors report a case of anaplastic thyroid carcinoma with lung metastasis, brain metastasis and an isolated metastasis to the small bowel leading intestinal obstruction due to small bowel intussusception. The Authors review the international literature about frequency, etiopathogenesis, clinical and diagnostic features and therapy of small bowel metastasis by extra-abdominal malignancies, especially by primary anaplastic thyroid carcinoma. Small bowel metastasis from extra-abdominal malignancies are very unusual, especially from anaplastic thyroid carcinoma, and the etiopathogenesis is still unknown. Clinical findings are typical for abdominal urgency, especially by small bowel obstruction from anaplastic thyroid carcinoma. Computed Tomography has an important role in detecting the type of intestinal obstruction despite it is often unable to diagnose an isolated metastasis. Best therapy is surgical resection, that allows the assessment of metastasis and the definitive staging. The prognosis is poor, despite long-term survival has been occasionally reported for isolated small bowel metastasis