Primary Squamous Cell Carcinoma with Thyroid Collision Tumors: A Case Report of Rare Thyroid Collision Phenomenon

Abstract

The term “collision tumor” is described as the coexistence of two or more histologically distinct neoplastic morphologies separated by normal tissue in the same organ. Collision phenomenon involving two and more neoplasms of the thyroid gland is a rare entity. A 54 year old female presented with a diffuse large swelling of thyroid gland increasing in size over a period of 20 years. Clinicoradiological examination reveal heterogenous enhancing lesion involving bilateral neck up to skull base. Patient underwent total thyroidectomy with central compartment clearance and bilateral selective neck node dissections. On histopathology, collision tumors with components of five histologically different entities were identified, including hurtle cell adenoma, well differentiated tumor of uncertain malignant potential, papillary thyroid carcinoma-classical variant, follicular variant of papillary thyroid carcinoma and primary squamous cell carcinoma of thyroid within different lobes of thyroid. To the best of our knowledge, this is the first documentation of a collision tumor with five histologically different entities within a single thyroid gland.

Keywords

• collision tumors
• follicular variant of papillary thyroid carcinoma
• hurtle cell adenoma
• primary squamous cell carcinoma
• papillary thyroid carcinoma
• well-differentiated tumour of uncertain malignant potential