陰莖瀰漫性大型 B 細胞淋巴瘤於免疫化學治療四個療程前後之臨床變化：病例報告

¹詹旻融、²許兆畬、³歐明哲、⁴曹唐義, ²林益聖、²歐宴泉、²童敏哲

¹童綜合醫院 一般醫學 ; ²童綜合醫院 外科部 泌尿科 ; ³童綜合醫院 內科部 血液腫瘤科 ; ⁴童綜合醫院 解剖病理科

Clinical and Metabolic Changes of Penile Diffuse Large B-Cell Lymphoma Before and After Four Cycles of Chemo-Immunotherapy: A Case Report

Min-Jung Jan¹, Chao-Yu Hsu² , Ming-Che Ou³, Tang-Yi Tsao⁴, Yi-Sheng Lin², Yen-Chuan Ou², Min-Che Tung²

¹Department of Medical Education, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan

²Division of Urology, Department of Surgery, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan

³Department of Hematology and Oncology, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan

⁴Department of Anatomical Pathology, Tungs' Taichung Metro Harbor Hospital, Taichung City, Taiwan

Abstract:

Primary penile diffuse large B-cell lymphoma (DLBCL) is an extremely rare extranodal lymphoma that may clinically mimic more common penile malignancies, leading to delayed diagnosis and inappropriate management. Due to the rarity of this disease, data regarding clinical course, staging characteristics, and treatment response remain limited. We present a rare case of primary penile DLBCL with serial FDG PET/CT findings before and after systemic chemo-immunotherapy.

Case presentation:

A 58-year-old man presented with a progressively enlarging painful penile mass that had been present for approximately three months and was refractory to empirical antibiotic therapy. The patient reported worsening penile pain and tenderness, significantly affecting daily activities. Physical examination revealed a firm mass involving the penile shaft.

Initial penile ultrasonography demonstrated a heterogeneous lesion surrounding the urethra within the tunica albuginea. Pelvic magnetic resonance imaging revealed a large soft tissue mass measuring approximately 8.0 × 4.6 cm involving the right corpus cavernosum and tunica albuginea, with imaging features suspicious for malignancy.

Ultrasound-guided core biopsy of the penile lesion was performed. Histopathological examination confirmed diffuse large B-cell lymphoma, centroblastic type, non–germinal center B-cell subtype with MYC and BCL-2 double expression.

Baseline fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated intense metabolic activity in the penile lesion, as well as additional extranodal FDG-avid involvement in the stomach, corresponding to Lugano stage IV disease.

The patient was treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy.

After four cycles of systemic therapy, the patient reported marked improvement in penile pain and swelling, with reduction in tumor size on physical examination. Follow-up FDG PET/CT demonstrated significant decrease in metabolic activity of the penile lesion, with reduced metabolic activity in the gastric lesion. No newly developed hypermetabolic lesions were detected. These findings were compatible with partial metabolic response to systemic chemo-immunotherapy.

Conclusion:

Penile lymphoma is a rare malignancy that can clinically mimic more common penile diseases and therefore requires heightened clinical awareness. Early recognition and tissue diagnosis are essential to avoid delayed or inappropriate management. FDG PET/CT plays a critical role not only in initial diagnosis and accurate staging, but also in monitoring treatment response. In this case, serial PET/CT demonstrated partial metabolic response after chemo-immunotherapy, highlighting the value of metabolic imaging in treatment evaluation of extranodal lymphoma.