A collision tumour of thyroid (papillary carcinoma + medullary carcinoma of thyroid): A rare case

The autosomal dominant condition known as neurofibromatosis type 1 is typified by neurofibroma tumors, which are renowned for being many cutaneous masses with a strong likelihood of becoming malignant. On the other hand, benign solitary retroperitoneal neurofibromas (SRN) are rare and manifest alone, without coexisting medical conditions. This 60-year-old man complained of a painless swelling Infront of Neck when he arrived at the general surgery outpatient department. A 10x6cm butterfly shaped swelling noted infront of neck, Surface of the swelling is smooth, lower border of swelling seen on deglutition, Engorged veins present. The ultrasonography showed a 1) well defined hypoechoic nodule with peripheral calcifications and internal vascularity in right lobe of thyroid-TIRADS-4.2) A heteroechoic lesion which is predominantly hyperechoic with few hypoechoic areas and calcifications seen replacing left lobe of thyroid seen inferiorly extending upto sternum- TIRADS-4. FNAC showed 1)Smear from left lobe of thyroid shows moderate cellularity comprising of small clusters and discrete thyroid follicular cells 2)Smear from right lobe of Thyroid shows scant cell yield composed of occasional thyroid follicular cells. Impression: Papillary Carcinoma of Thyroid-TBSRTC-IV. CECT Neck showed both lobes of thyroid gland are enlarged in size with evidence of multiple nodules, calcifications and heterogeneous enhancement, Left lobe of thyroid is showing retrosternal extension into superior mediastinum-possible multinodular goitre Total Thyroidectomy with central neck dissection was done and sample excised was sent for HPE. This case reports presents a rare case of Papillary and medullary carcinoma of thyroid, a collision tumor, a rare incidence.