(14.14) Primary Thyroid B-Cell Lymphoma: Rare Location, Unique Presentation

Primary Thyroid Lymphoma (PTL) is a rare and aggressive malignancy, accounting for approximately 5% of thyroid cancers, with a significantly higher incidence in autoimmune chronic thyroiditis. We present a compelling case of a 77-year-old female with history of Hashimoto's thyroiditis who developed a rapidly growing thyroid mass, ultimately diagnosed as B-cell lymphoma.

Case(s) Description :

The patient presented with dysphagia and dyspnea from a large neck mass causing airway compression and needing intubation. Diagnostic imaging revealed a 5.0 cm x7.6 cm x 9.8 cm neck mass arising from the left thyroid gland, encasing left internal carotid artery, extending to retropharyngeal space with tracheal compression and deviation. Initial thyroid function tests returned within normal limits (TSH of 2.4 mlU/ml and free T4 of 1.7 ng/dl) while on replacement with levothyroxine 100 mcg daily. Further imaging, including CT brain, chest, abdomen and pelvis were obtained to rule metastatic process. Staging imaging was concerning for advanced disease on both sides of diaphragm. Core biopsy with flow cytometry from left thyroid mass confirmed aggressive high-grade B-cell lymphoma, leading to the prompt initiation of R-CHOP chemotherapy. Despite a complex hospital course, including pneumonia and pulmonary embolism, the patient's airway was preserved. However, due to persistent dysphagia a percutaneous endoscopic gastrostomy (PEG) tube was placed.
 

Discussion :

Diffuse Large B-Cell Lymphoma (DLBCL), encompassing 70% of PTL cases, demands multimodal treatment. The Lugano staging system directs PTL staging, with surgical intervention reserved primarily for airway protection. Diagnostic procedures involved ultrasound, often supplemented by CT scans to assess disease extension. Fine needle aspiration and flow cytometry, along with core needle biopsy for subtyping, played pivotal roles in guiding the diagnosis. The case underlines the urgency of core needle biopsy when lymphoma is suspected in thyroid masses.

In conclusion, the presented case emphasizes the significance of considering PTL in the context of rapidly growing thyroid masses, especially in patients with a history of autoimmune chronic thyroiditis. Early and accurate diagnosis through core biopsy with flow cytometry is essential for distinguishing PTL from other thyroid malignancies. Managing PTL's aggressive nature requires early detection and intervention to preserve patient outcomes.