Table 4_A case report and diagnostic-therapeutic analysis of de novo bilateral papillary thyroid carcinoma complicated with stage I a diffuse large B-cell lymphoma (ABC subtype, double-expressor).docx

This article reports a 49-year-old female patient with de novo double primary bilateral PTC (with right cervical lymph node metastasis, metastasis rate 4/6) and stage I A DLBCL (not otherwise specified, activated B-cell-like subtype, double-expressor). The diagnosis was confirmed by preoperative imaging evaluation, puncture biopsy pathology, as well as postoperative specimen pathology, immunohistochemistry, and fluorescence in situ hybridization (FISH) detection.

The patient received radical thyroidectomy combined with polatuzumab vedotin (Pola)-anti-CD20 monoclonal antibody-CHP regimen for immunochemotherapy. Grade III neutropenia occurred during treatment, which returned to normal after symptomatic treatment and secondary prevention, with good tolerance in subsequent treatment. After 6 cycles of immunochemotherapy, DLBCL achieved complete remission (CR), and the patient recovered well after thyroidectomy, completing planned iodine-131 therapy postoperatively.

As of October 2025, the total follow-up duration was 6 months, with no signs of tumor recurrence noted to date; nevertheless, longer-term continuous surveillance is still required to definitively exclude late relapse risk, given the aggressive nature of double-expressor DLBCL. Meanwhile, combined with the diagnosis and treatment process of this case and relevant literature, we discuss the clinical characteristics, diagnostic key points, and individualized treatment strategies of double primary DLBCL and PTC, aiming to provide a reference for the standardized diagnosis and treatment of similar rare clinical cases.</p>