A 35-year-old male presented with gross haematuria with similar episodes occurring in the past 6 months. No H/O of fever, pain, or burning on urination weight loss or increased sense of urgency to void. There was no history of exposure to toxins either at work or during recreational activities. The patient underwent fibreoptic cystoscopy. A mass was noted in the fundus of the bladder, biopsy of which is shown in Figure. What is the drug of choice of the likely cause?

**Core Concept**
The patient's presentation of gross haematuria, a mass in the fundus of the bladder on fibreoptic cystoscopy, and the biopsy results suggest a diagnosis of bladder cancer, specifically transitional cell carcinoma (TCC). The primary treatment for TCC involves surgical resection and adjuvant chemotherapy.

**Why the Correct Answer is Right**
The drug of choice for the likely cause, bladder cancer, is a chemotherapeutic agent that targets rapidly dividing cells. Cisplatin (Option C) is a platinum-based chemotherapeutic agent that is commonly used in the treatment of bladder cancer, particularly in cases of muscle-invasive TCC. Cisplatin works by forming platinum-DNA adducts that inhibit DNA synthesis and function, leading to cell death. The correct answer is supported by the National Comprehensive Cancer Network (NCCN) guidelines, which recommend cisplatin as a first-line treatment for bladder cancer.

**Why Each Wrong Option is Incorrect**
**Option A:** Carboplatin is a platinum-based chemotherapeutic agent similar to cisplatin but is less commonly used in the treatment of bladder cancer due to its lower efficacy and higher toxicity profile.
**Option B:** Paclitaxel is a taxane chemotherapeutic agent that is primarily used in the treatment of ovarian, breast, and lung cancers, but not typically in bladder cancer.
**Option D:** Cyclophosphamide is an alkylating agent that is used in the treatment of various types of cancer, but it is not the drug of choice for bladder cancer.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the treatment of bladder cancer often involves a multimodal approach, including surgery, chemotherapy, and radiation therapy. The choice of treatment depends on the stage and grade of the cancer, as well as the patient's overall health and performance status.

**Correct Answer:** C. Cisplatin.

✓ Correct Answer: C. Praziquantel