Introduction
Plasmacytoid urothelial carcinoma (PUC) is rare, and is known to mimic invasive lobular carcinoma of the breast and signet cell gastric adenocarcinoma. PUC has a very poor prognosis, with high cancer mortality, despite being chemo-sensitive, largely due to its high recurrence rate. Metastatic lesions presenting as bladder tumours, are also rare and has poor prognosis when presenting as a widespread metastatic disease process.

Patient Background
A 69-year-old woman with a history of metastatic lobular carcinoma of the breast was noted to have new unilateral hydronephrosis with associated luminal thickening of the proximal right ureter. She originally had a previously wide local excision thirteen years prior, subsequently re-excision then requiring salvage mastectomy due to positive margins. She underwent appropriate neoadjuvant chemotherapy and anastrozole. She then developed evidence of gastric involvement of lobular carcinoma. She was then placed on exemestane which showed radiological and biochemical regression. The finding of hydronephrosis was identified on surveillance imaging with no haematuria.

Clinical findings
Given the clinical findings the patient came forwards for ureteroscopy. Upon entering the bladder, a small raised erythematous lesion was identified just below the right ureteric orifice and was biopsy. Ureteroscopy of the affected ureter was abandoned due to excessive tightness of the ureter. Ureteric washings of the renal pelvis were taken, and a retrograde pyelogram was performed. A 6 Fr stent was placed.

Diagnosis
Despite the initial histology suggestion of PUC, clinical correlation and evaluation of the ureteric washing sample was in keeping with metastatic lobular. Evaluation of the ureteric washings revealed mammaglobin positive, and oestrogen receptor and progesterone receptor positive.

Treatment
Given the asymptomatic nature of metastatic disease, the patient was kept under observation. Unfortunately, the patient presented acutely with contralateral hydronephrosis, due to extrinsic compression from a metastatic peritoneal deposit. Retrograde decompression with a JJ stent was performed and subsequent palliative paclitaxel and then Palbociclib were trailed.

Conclusion
PUC is a rare variant malignancy, and clinicians should be aware of its mimicry of metastatic malignancy. The need for clear communication between surgical and pathology teams is also highlighted for accurate reporting. Positive staining of mammaglobin and hormone receptors in a bladder tumour with initial appearance of plasmacytoid urothelial carcinoma should raise suspicion for metastatic lobular carcinoma of the breast.

Metastatic Invasive Lobular Carcinoma Mimicking Plasmacytoid Urothelial Carcinoma of the Bladder

For 2021, our focus remains: turning new data into your daily practice. The programme will consist of state-of-the-art lectures, case discussions and panel debates. Our faculty is a group of international & multidisciplinary experts.

We will take you on our journey to Ghent and beyond. Prior the congress, we send out case challenges, where you can compare your opinion with peers & experts. These cases will be part of the Global Congresses on Prostate & Bladder Cancer programme during the congress days (12 & 13 October for PROSCA and 14 & 15 October for BLADDR). After these days, you will be updated on prostate & bladder cancer management.