Case Report: Primary clear cell adenocarcinoma of the urethra-imaging features and literature review

Primary clear cell adenocarcinoma of the urethra (PCCAU) is an extremely rare malignant tumor. Its clinical manifestations are nonspecific, and preoperative diagnosis relies primarily on imaging studies. To date, most reports on this disease are isolated case presentations, and systematic studies correlating imaging findings with pathological results remain scarce.

A 58-year-old woman was admitted due to voiding dysfunction for 14 months, worsened with gross hematuria for 2 months. Preoperative imaging evaluation included ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). US revealed an irregular hypoechoic mass in the post-bladder urethral region with minimal internal blood flow; CT scan indicated a heterogeneously enhancing mass in the urethral area accompanied by necrotic changes; MRI demonstrated a periurethral lesion showing a slightly high signal on T2-weighted imaging (T2WI) with a low-signal capsule. Diffusion-weighted imaging (DWI) showed restricted diffusion, with an apparent diffusion coefficient (ADC) value of 0.79 × 10^-³ mm²/s, heterogeneous enhancement in the arterial phase of dynamic contrast-enhanced imaging, and a centripetal filling pattern. Postoperative histopathology confirmed the diagnosis of PCCAU. Immunohistochemical findings were as follows: AE1/AE3 (+), CK7 (focal +), PAX8 (+), P504S (+), Napsin A (scant +), p53 (~5%+), and Ki-67 (~35%+). The patient declined adjuvant therapy after surgery. Seven months postoperatively, she developed lymph node metastasis and peristomal metastasis around the right ureteral abdominal wall orifice, and was subsequently treated with toripalimab immunotherapy. She remained alive at the 1-year postoperative follow-up.

PCCAU is extremely rare. Imaging examinations, particularly multimodal MRI, combined with histopathological and immunohistochemical analyses, play a crucial role in its diagnosis. Early surgical intervention contributes to improved prognosis, and personalized treatment strategies, including immunotherapy, may offer clinical benefits in advanced cases.