MALIGNANT COLLISION TUMORS OF THYROID: TWO CASE REPORTS

Collision neoplasm is when two different types of tumors affect the same organ. Collision tumors of the thyroid are extremely rare. This paper describes two cases of patients who had these mixed tumors. The first case is a 59-yearold male patient who presented complaining of mass that was growing for over a year. After a thorough investigation the patient was initially diagnosed with Papillary Thyroid Carcinoma (PTC) and thyroidectomy was performed, however further histologic evaluation of the gland revealed PTC and Medullary Thyroid Carcinoma (MTC). The second case was of a 21-year-old female who presented with a neck swelling for only a month. Radiograph showed two nodules of variable sizes on right and left lobes. After an FNA a diagnosis of PTC was made. The patient later on had a complete thyroidectomy. Histology of the gland revealed PTC in right lobe and Oncocytic carcinoma in left lobe. Since CT tumors are rare, the diagnosis could be challenging. Although, it is of great importance as in some cases the management depends on it. The reported cases here shed the light on the importance of careful and meticulous histological diagnosis, as the accompanied tumors with PTC were both incidentally found.