Endocrine Abstracts

Introduction: Primary thyroid lymphoma is rare and accounts for less than 5% of all thyroid malignancies. The risk is almost 60 times higher in those with thyroiditis and is more common in females, with a ratio of 4:1. The most frequent local symptom is a rapidly enlarging thyroid gland along with the resultant obstructive symptoms. Fine needle aspiration is the initial diagnostic procedure for thyroid tissue sampling. The main differential diagnosis is anaplastic thyroid carcinoma by its aggressive behaviour and rapid growth.

Case Report: A 69 year old man was referred to our outpatient clinic with a symptomatic, rapidly growing cervical mass with an ultrasound suggestive of thyroid cancer. The patient primarily complained of progressive dysphagia and, more recently, hoarseness related to the past 4 weeks rapid enlargement of the thyroid gland. Past medical history included multinodular goiter and thyroiditis, having been discharged from our specialized consultation 4 years prior to this event. Fine needle aspiration cytology was performed, with no conclusive result, showing signs of cystic degeneration and chronic thyroiditis. A surgical biopsy was then proposed and undertaken 2 weeks later. Immunohistochemistry study favored a tumor of lymphoid-hematopoietic/histiocytic origin. However, the highly proliferative representation of the tumor, along with conflicting histochemistry marker positivity, determined another inconclusive diagnosis. As time went by, dysphagia got worse and orthopnea ensued. The lacking histologic diagnosis prevented our patient from starting any type of systemic therapy. The previously incised skin became infiltrated with the underlying tumor. Given the imminent airway compromise, the patient was submitted to a percutaneous endoscopic gastrostomy and an attempt at a tracheostomy procedure which could not be done due to significant posterior displacement of the trachea and risk of direct airway invasion. A second incisional biopsy was performed which excluded any malignant epithelial proliferation and confirmed the diagnosis of a T-cell/histiocyte rich large B-cell lymphoma. CT staging found 2 possible secondary lesions in the right lung and involvement of paratracheal nodes. He was started on systemic therapy with R-CHOP protocol and for the moment awaits restaging.

Conclusion: Primary thyroid lymphoma remains an extremely rare and life-threatening occurrence. Its high proliferation rate makes the histologic diagnosis both challenging and urgent, given that time is of the essence when a rapidly growing bulky thyroid mass threatens the airway. Bailout procedures should be sought when a definitive airway is not feasible.