Multifocal Diffuse Sclerosing Papillary Thyroid Carcinoma: A Rare Variant with Diagnostic Challenges

Abstract

Diffuse sclerosing papillary thyroid carcinoma (DS PTC) is a relatively rare variant of papillary thyroid carcinoma. It is characterized by distinct histological features like scattered microscopic tumor islands, diffuse sclerosis, lymphocytic infiltration, numerous psammoma bodies, radiological features like snowstorm appearance and biologically aggressive behavior in the form of invasion and metastasis. A preoperative diagnosis is often challenging in the absence of nodules and scanty fine needle aspiration cytology sample. We describe a case of multifocal diffuse sclerosing variant of papillary thyroid carcinoma in a 29 year old young male who presented with a swelling in the right side of neck of 2 month duration in the absence of a visible thyroid swelling. Neck swelling was non tender, well defined, firm, not moving with deglutition. Laboratory studies showed normal thyroid function, neck ultrasound revealed heteroechoic right lobe with multiple punctate echogenic foci and enlarged right sided cervical nodes with echogenic foci, fine needle aspiration cytology of which was consistent with metastasis from papillary adenocarcinoma. Based on the above investigations, a total thyroidectomy with central compartment lymph node dissection and modified radical neck dissection of right side was performed. Histological analysis revealed Multifocal Diffuse Sclerosing variant of papillary Thyroid Carcinoma. Clinical and histological challenges usually occur when DS PTC present as diffuse thyroid enlargement, dispersed microscopic tumor islands, extensive fibrosis, abundant lymphocytic infiltration mimicking thyroiditis and when the fine needle aspiration cytology sample is non representative.