Primary Adrenal Lymphoma Diagnosed by Endoscopic Ultrasound Fine-Needle Aspiration Biopsy: A Case Report

BACKGROUND Primary adrenal lesions pose significant diagnostic challenges, as noninvasive imaging often fails to differentiate malignant from benign lesions. Percutaneous fine-needle aspiration (FNA) could be risky and undiagnostic, particularly in patients with hematologic disorders and low platelet counts. Performing surgery risks adrenal dysfunction, potentially resulting in poor prognosis. Since adrenal glands are located in the retroperitoneal space, endoscopic ultrasound-guided FNA (EUS-FNA) may be a good choice to obtain biopsy. While adrenal metastasis diagnosed by EUS-FNA has been reported, primary adrenal lymphoma (PAL) detected incidentally in asymptomatic patients remains undocumented in literature. CASE REPORT A 72-year-old man presented to our hospital with bilateral adrenal lesions (4.3×1.3 cm left, 3.7×2.0 cm right) found via ultrasound. Further examinations suggested lymphoma, but low platelet counts made surgery and percutaneous FNA dangerous. With the assistance of gastroenterologists, EUS-FNA was performed safely and successfully led to diagnosis of primary adrenal diffuse large B-cell lymphoma. Based on this diagnosis, the patient underwent R-CHOP chemotherapy followed by radiotherapy. At the 1-year follow-up, the left adrenal lesion was reduced in size, and the right lesion had resolved completely, indicating clinical remission. CONCLUSIONS PAL is a rare and life-threatening disease, and its retroperitoneal location and potential association with thrombocytopenia can render conventional biopsy methods high-risk procedures. Despite thrombocytopenia, EUS-FNA remains a safe and effective method for diagnosing PAL without harming normal adrenal function. Moreover, the biopsy specimens obtained through this approach were sufficient to establish a definitive lymphoma diagnosis and guide subsequent therapeutic interventions. This approach provides a novel diagnostic alternative for PAL.