Difficulties in Differential Diagnosis of Aggressive Forms of Thyroid Cancer

Papillary carcinoma is the most common type of thyroid cancer, accounting for more than 85 % of all types of thyroid tumors. Currently, more than 15 histopathological variants of papillary thyroid cancer have been described, based on specific growth patterns, cell types, and stromal changes. This article describes a clinical case of complex differential diagnosis between diffuse sclerosing and cribriform morular forms of thyroid cancer in a young patient. Diffuse sclerosing variant of papillary thyroid cancer is a rare subtype of thyroid cancer, accounting for less than 6 % of papillary thyroid cancers. Among thyroid tumors, a rare variant of papillary cancer is identified – cribriform morular cancer, which occurs in less than 0.5 % of cases. Similar morphological characteristics of thyroid tumors with their different immunohistochemical and molecular genetic profiles make it difficult to establish a final diagnosis and may influence further treatment tactics. In this case of a comprehensive differential diagnosis, the patient achieved results that allow us to recommend further specialized systemic treatment in order to minimize the risk of disease relapse.