Metastatic Anaplastic Thyroid Carcinoma Presenting with Gastrointestinal Bleeding: A Case Report and Literature Review

Background: Thyroid cancer is increasing, particularly the differentiated type, with decreasing incidence of the anaplastic type. Anaplastic thyroid carcinoma (ATC) is a rare, aggressive, and often lethal form. It frequently presents with metastatic disease, regional and systemic, with common distant metastasis to the lung, bone, brain, and adrenal, and rarely to other places. Case presentation: A 74-year-old Arab male presented with symptomatic anemia and melena and was admitted for investigation of the cause. The patient was found to have a large retrosternal goiter and gastric tumor. CT scan showed a pedunculated, nonobstructive mass, suggestive of a GIST or leiomyoma. The neck mass presented with compressive symptoms. He underwent a combined neck and abdominal surgical resection based on a multidisciplinary team decision, as prior biopsies were not conclusive. The final pathology report identified similar tumors in the two specimens and suggested an anaplastic thyroid carcinoma as the primary tumor with metastasis to the stomach. Furthermore, the workup, including a PET scan 2 weeks post-surgery, revealed widespread metastases in the bone, lung, and liver, and the treatment was palliative. He was followed up in the outpatient clinic for 4 and a half months post-operatively. The patient developed sepsis and cardiopulmonary arrest and died. Conclusions: ATC can metastasize to many places in the body, including the stomach (as shown in our case), which can cause significant upper gastrointestinal bleeding and anemia. Metastatic ATC carries a poor prognosis; thus, physicians need to keep a high index of suspicion in approaching similar cases. A multidisciplinary approach for the management is of utmost importance for appropriate treatment. This disease’s pathology, behavior, and targeted new treatment modalities must be explored further.