BACKGROUND: Anaplastic thyroid carcinoma (ATC) is an uncommon and aggressive form of human cancer. Despite advancement in multimodal therapy for patients with ATC, the prognosis remains poor. Most patients presenting with ATC have metastasis to the lungs and regional lymph nodes. Gastrointestinal tract metastasis is a rare entity observed among patients with ATC. We report a case of ATC with gastrointestinal metastasis.

CASE REPORT: A 72-year-old euthyroid female with hypertension presented to the clinic with swelling of the neck and breathlessness. Fine needle aspiration cytology revealed colloid goiter. Positron emission tomography and computed tomography revealed hypermetabolic, lobulated mass in left hemi-thyroid, displacing trachea, and hypermetabolic lymph nodes on the left side. The patient underwent total thyroidectomy along with left modified radical neck dissection. Histopathology and immunochemistry were suggestive of ATC with thyroid transcription factor 1 (TTF-1), cytokeratin, Pax8, and C53 positive while calcitonin and thyroglobulin were negative. The patient presented with persistent nausea and vomiting during adjuvant radiation therapy. After radiation therapy, the patient underwent upper gastrointestinal endoscopy that revealed large polypoidal lesions in the stomach. No active bleeding was observed. Biopsy results confirmed it to be metastasis from ATC.

CONCLUSIONS: ATC can spread to distant sites including the gastrointestinal tract. Patients with ATC metastasis have a poor prognosis despite multimodal therapy. This is the first case of ATC with gastrointestinal metastasis reported in India.

Keywords: Carcinoma, Endoscopy, Gastrointestinal, Thyroid (USP), Thyroid Carcinoma, Anaplastic