Neck and Neck: To treat or not to treat- that is the question

Summary: Primary thyroid lymphoma (PTL) is a rare malignancy, constituting 5% of all thyroid cancers and < 3% of non-Hodgkin’s extra-nodal lymphomas. There are limited numbers of randomized or prospective trials to guide management, and optimal treatment remains subject to debate. Herein, we present a case of PTL status-post thyroidectomy followed by adjuvant chemoradiation (CRT), to demonstrate the feasibility and safety of this treatment modality, and to discuss existing literature. A 68-year-old female initially presented with dysphagia, hoarseness, and globus sensation. She underwent thyroid ultrasound, which showed a 5.1 cm solid hypoechoic right-sided nodule. Excisional biopsy was suspicious for papillary carcinoma, but low cellularity in the aspirated material complicated the results. The patient underwent total thyroidectomy, with pathology demonstrating aggressive, mature diffuse large B-cell lymphoma (DLBCL) of the thyroid, Ki-67 proliferation index of 100%, extensive necrosis, and focal EBER positivity. Fluorescent in-situ hybridization (FISH) studies were negative for BCL6, MYC, and BCL2 gene rearrangement. PET/CT showed a probable inclusion cyst in the posterior right neck but was otherwise negative. Patient was therefore staged IE bulky, NCCN-IPI low-intermediate risk. The patient received 4 cycles of adjuvant R-CHOP, with post-chemotherapy PET/CT demonstrating no residual disease. Afterwards, she underwent consolidative radiation therapy to 30 Gy in 15 fractions via daily image-guided IMRT photon therapy, covering the tumor bed and bilateral lymph nodes. At her 5-month follow-up, the patient continued to experience dysphonia, moderate dysphagia and xerostomia. Examination revealed soft phonation; otherwise, no cervical masses, adenopathy, or tenderness were noted. Laryngoscopy showed normal vocal fold mobility and hyperfunction. She was referred to speech therapy for vocal exercises, with significant improvement in phonation at her 6-month follow-up. Thyroid lymphomas present unique challenges in management, as standards of care are not well established. Involved-site radiation therapy (ISRT) may be effective; however, a more comprehensive radiation field may be justified in the presence of aggressive histological features or bulky adenopathy with stage I DLBCL. It remains unclear whether the patient's total thyroidectomy obviates the need for additional local therapy, but literature suggests a possible benefit of CRT over surgical resection alone, with evidence of high cure rates and improved disease-free survival with adjuvant radiation. Continued investigation is needed to guide evidence-based decision-making on the extent of treatment fields and nodal volumes in these cases. Jovan Z. Pierre-Charles (he/him/his), MD (Presenting Author) - University of Kentucky; Waleed F. Mourad, MD (Co-Author) - University of Kentucky; Aradhana Kaushal, MD (Co-Author) - University of Kentucky; Evans Amoah, MD (Co-Author) - University of Kentucky; James A. Knight, Resident Physician (Co-Author) - University of Kentucky