Abstract
<title>Abstract</title> <p>Background: Extranodal natural killer/T-cell lymphoma, nasal type (ENKTCL-NT) is a rare and highly aggressive subtype of non-Hodgkin lymphoma. Its diagnosis is often extremely challenging due to the lack of specific imaging markers. Although ultrasound-guided core needle biopsy (CNB) is a standard technique for detecting breast lesions, conventional ultrasound has difficulty in clearly demonstrating the heterogeneous blood flow characteristics of ENKTCL-NT, leading to deviations in biopsy positioning. This case report innovatively integrates contrast-enhanced ultrasound (CEUS) and CNB techniques, and for the first time systematically explores the precise diagnostic value of CEUS-guided CNB in breast ENKTCL-NT. Case Presentation: A 35-year-old female with a 3-year history of treated ENKTCL-NT in the right orbit presented with right breast pain for four months. A month prior, ultrasound at an external hospital revealed a 4×3 cm hypoechoic mass (BI-RADS 4C) in the right breast, accompanied by increased skin temperature. However, percutaneous biopsy failed to confirm the diagnosis. Upon referral to our hospital, physical examination revealed ulcers and scabs on the right breast. Laboratory testing detected elevated Epstein–Barr virus DNA load (8.62×10³ copies/ml). Diagnosis and Interventions: The previous unsuccessful biopsy indicated insufficient targeting of viable tumor regions. A combined CEUS-CNB strategy was adopted: After intravenous injection of sulfur hexafluoride microbubble contrast agent, the tumor exhibited heterogeneous hypo-enhancement in the arterial phase, accompanied by patchy and marked perfusion defects, followed by rapid washout (faster than surrounding breast tissue) and persistent marked hypo-enhancement in the venous phase. Ultrasound-guided CNB was precisely performed in the area with the most abnormal blood flow signals, as localized by CEUS perfusion defects. Outcomes: Pathological analysis confirmed the recurrence of ENKTCL-NT in the right breast. The patient subsequently received radiotherapy, chemotherapy, and immunotherapy to slow disease progression. Conclusion: This case report reveals the application value of CEUS in the diagnosis of ENKTCL-NT in the breast. By demonstrating the hypoenhancement patterns and perfusion defects associated with the lesions, CEUS can provide crucial imaging clues for early detection and differential diagnosis. CEUS can provide crucial imaging clues for early detection and differential diagnosis. Based on the evaluation of blood flow heterogeneity by CEUS, the selection of the target area for ultrasound-guided core needle biopsy can be further optimized, thus improving the efficiency of pathological confirmation.</p>