Case report: poorly differentiated thyroid carcinoma in a young female patient

Background: Poorly differentiated thyroid carcinoma (PDTC) is a rare subtype of thyroid cancer that is often overlooked on differentials for thyroid neoplasms, and its etiology is poorly understood. This report provides an additional clinical and genetic profile to the literature of this rare and often complex entity as well as discusses a multitude of genetic findings seen in PDTC. Case Description: A young female patient (<21) presented to her primary care provider with a history significant for a large, asymptomatic, right sided, immobile neck mass. A CT scan revealed a mass measuring 4.0×4.0×2.6 cm3 lying adjacent to the thyroid. The mass was subsequently removed via a right hemithyroidectomy. The histology demonstrated a diffuse trabecular, and solid growth pattern consisting of poorly differentiated follicular cells with mitotic figures, capsular invasion, lymphovascular invasion, nerve involvement and focal areas of necrosis. Immunohistochemical stains were performed and were useful in determining the tumor’s thyroid origin. Multiple pathology consults were obtained in the workup for this case along with the application of the Turin criteria. The patient was recommended to undergo a complete thyroid resection and seek genetic counseling due to a known association between this disease and a rare syndrome known as DICER syndrome. Genetic studies did not identify a DICER1 mutation, and the patient was lost to follow-up after referral to a tertiary care center. Conclusions: This tumor type is rare in this age group and has few studies explaining its etiology. The genetic analysis in this case had a unique genetic profile showing MYC amplification and mutations of undetermined significance without the previously reported finding of a DICER1 mutation.