ODP473 Critical Airway Obstruction Resolving with Medical Management of Newly Diagnosed Thyroid Lymphoma

BACKGROUND: Thyroid lymphoma is a rare malignancy that accounts for 1-5% of thyroid malignancies. The classic presentation of thyroid lymphoma is a rapidly enlarging, painless goiter. The main modalities used to confirm lymphoma are thyroid ultrasound and FNA. We report a case of critical airway obstruction (<5 mm) requiring core needle biopsy to diagnose thyroid lymphoma, with resolution of obstruction following chemotherapy. CASE: A 60-year-old man with a history of hypertension and BPH presented to the hospital with two weeks of progressive shortness of breath and dysphagia. He denied weight loss, night sweats, or thyroid dysfunction. CT demonstrated thyromegaly with substernal extension along with extension into tracheal-esophageal grooves, encasing the trachea with possible right sided tracheal invasion and tracheal narrowing to 4 mm. Thyroid ultrasound demonstrated an enlarged thyroid replaced by heterogenoushypoechoic lobular masses. Additional imaging demonstrated a 4 cm perirenal mass. Laboratory evaluation demonstrated TSH 0.97 uIU/mL (0.4–4. 0 uIU/mL), free T4 0.8 ng/dL (0.6-1.5 ng/dL), anti-TPO 16.9 IU/mL (<5. 0 IU/mL), and LDH 262 U/L (<240 U/L). He underwent a bronchoscopy which showed 60% tracheal obstruction 1 cm below the vocal cords. He underwent 2 FNAs which both resulted as Bethesda 3. The first FNA demonstrated lympho-histiocytic infiltrate, scant spindled cells and follicular cell groups with oncocytic features. The second FNA demonstrated chronic lymphocytic thyroiditis. Due to worsening respiratory status, he was given high dose dexamethasone and planned for tracheal stenting. He subsequently underwent a core needle biopsy demonstrating marked atypical B cell infiltration, concerning for mature large B cell lymphoma. Immunoperoxidase studies demonstrated atypical cells positive for CD10, 20, 79a, BCL-2, 6, and PAX5 with a 90% Ki67 proliferation diagnosing diffuse large B cell lymphoma. Biopsy of his perirenal mass was negative for lymphoma or carcinoma. He began R-CHOP chemotherapy and after one cycle experienced resolution of difficulty breathing, dysphagia, and thyromegaly. Tracheal stenting and thyroidectomy were thus avoided. After 4 cycles of R-CHOP, a PET CT demonstrated no evidence of residual lymphoma. A repeat thyroid ultrasound also demonstrated resolution of both thyromegaly and hypoechoic nodules. CONCLUSIONS: Patients with a rapidly enlarging goiter and obstructive symptoms should undergo evaluation for thyroid lymphoma, particularly if they have a history of Hashimoto's thyroiditis or positive TPO antibodies even when euthyroid upon presentation. Though FNA is the first line modality used to diagnose thyroid lymphoma, our case highlights the need to proceed with a timely core needle biopsy if FNA is non-diagnostic to obtain a definitive diagnosis. Once the diagnosis of thyroid lymphoma is confirmed, management with R-CHOP chemotherapy rapidly improves obstructive symptoms, avoiding unnecessary surgical intervention even in the setting of critical airway obstruction. References: Stein et al. JCEM. 2013; 98(8): 3131-3138Walsh et al. The Oncologist. 2013;18(9): 994-1003 Presentation: No date and time listed