Acute "Crack-Like" Hemorrhage of the Thyroid During Fine-Needle Aspiration Biopsy: A Case Report

Fine-needle aspiration biopsy (FNAB) is the preferred pathological examination to exclude thyroid cancer. We describe two case studies of acute thyroid lytic hemorrhage and swelling with pain during FNAB. We observed hemorrhages with a crack-like appearance and swelling during the first needle prick, accompanied by pain, in two patients with no coagulation dysfunction. Symptoms were relieved after the intervention. Thyroid hemorrhage with a crack-like pattern is a rare acute hemorrhagic complication of FNAB. The cause is unclear, and an allergic reaction of the glands could not be excluded. Emergency measures must be prepared in advance, as unpredictable complications may occur during FNAB.