Severe Inflammatory Cystitis and Ureteritis Following Neoadjuvant TCHP (Docetaxel, Carboplatin, Trastuzumab, and Pertuzumab) Therapy in HER2-Positive Breast Cancer: A Case Report and Literature Review.

Haematuria is a rare complication in patients receiving docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) chemotherapy for breast cancer, with only a few cases reported. Here, we describe a 65-year-old woman with HER2-positive T2N1 breast cancer who developed visible haematuria and acute kidney injury (AKI) after her first cycle of neoadjuvant TCHP therapy. Ultrasound and computed tomography (CT) imaging of the renal tract demonstrated mild bilateral hydronephrosis and moderate bilateral hydroureter associated with inflammatory fat stranding, with findings most consistent with chemotherapy-associated inflammatory ureteritis and cystitis. Initial management included continuous bladder irrigation, intravenous fluids, and empirical antibiotic therapy. However, persistent haematuria and worsening renal function despite supportive treatment prompted initiation of oral prednisolone 60 mg once daily for presumed inflammatory urothelial toxicity. The patient showed a marked clinical response within 72 hours of corticosteroid initiation, with resolution of haematuria and recovery of renal function to baseline. Following multidisciplinary team (MDT) discussion, and given poor tolerance of systemic therapy alongside significant treatment-related anxiety, a decision was made to proceed directly to surgery rather than continue neoadjuvant chemotherapy. This case highlights chemotherapy-associated urothelial toxicity as a rare but clinically significant adverse effect of TCHP therapy and the need for early recognition and multidisciplinary management. A focused review of previously reported cases is also presented.