Metastatic Malignant Peripheral Nerve Sheath Tumor To the Thyroid - Metastatic Malignant Peripheral Nerve Sheath Tumor To the Thyroid - Open Access Pub

It is extremely rare that sarcomas metastasize to the thyroid. We report a case of a 49 year old male with malignant peripheral nerve sheath tumor (MPNST) metastatic to the thyroid that was diagnosed by ultrasound guided fine needle aspiration (FNA). The FNA cytology showed numerous loosely cohesive pleomorphic small spindle cells, some of which were arranged in short fascicles or haphazard pattern. The nuclei were oval or spindle in shape, with hyperchromatic granular chromatin and inconspicuous nucleoli, and smooth nuclear membrane contours. The cytoplasm was scant to moderate in amount, and delicate. Some cells had long thin cytoplasmic projections. Based on the cytomorphology, a diagnosis of “consistent with metastatic MPNST from small intestine” was rendered and follow-up thyroidectomy confirmed the cytologic diagnosis. Therefore, FNA biopsy is a useful, easy to perform, cost effective, safe procedure that can diagnose secondary tumors of the thyroid, and help avoid unnecessary thyroidectomy in patients with a poor prognosis. DOI10.14302/issn.2574-4496.jtc-15-779 Malignant tumors of the thyroid gland were estimated to account for 3.8% of all malignancies in the United States in 2014 according to National Cancer Institute report (http://seer.cancer.gov/statfacts/html/thyro.html). According to the tumor classification of the World Health Organization (WHO), thyroid tumors are classified as epithelial or nonepithelial, benign or malignant, primary or metastatic tumors, with a separate category for lymphomas and miscellaneous neoplasms.1 Solitary thyroid nodules are common in clinical practice, however, nodular intrathyroid metastases are rare and may be underestimated.2 In most clinical reviews the incidence ranges from 2% to 3%. In autopsy studies, the incidence of intrathyroid metastases of non-thyroid origin ranges from 1.9% in unselected studies to 24% in patients with widespread malignant neoplasms.3, 4 In a review of 43 cases of metastatic disease to thyroid gland, the kidney was the most common primary tumor site (33%), followed by lung (16%), breast (16%), esophagus (9%), and uterus (7%).5 Soft tissue sarcomas metastatic to the thyroid are extremely rare with a few cases reported in the literature including10 leiomyosarcomas from uterus, leg and duodenum,6, 7, 8 2 histiosarcomas from the ankle or the thigh,9, 10 1 endometrial carcinosarcoma,11 and 1 liposarcoma of the thigh.12 We report a rare case of metastatic malignant peripheral nerve sheath tumor (MPNST) from the ileum diagnosed in the thyroid by fine needle aspiration (FNA) biopsy. The