**Core Concept**
Transitional cell carcinoma (TCC) of the bladder is a common malignancy in adults, often presenting with painless hematuria. The management of TCC depends on the tumor's grade, stage, and histological subtype. In this case, the tumor is a low-grade papillary TCC with no muscle invasion, which is amenable to organ-preserving therapies.

**Why the Correct Answer is Right**
Intravesical BCG (Bacillus Calmette-Guerin) is a form of immunotherapy that involves instilling live attenuated Mycobacterium bovis into the bladder. BCG stimulates an immune response against tumor cells, thereby reducing the risk of recurrence and progression. The mechanism of action involves the activation of immune cells, such as macrophages and T lymphocytes, which release cytokines and chemokines that target TCC cells. The use of BCG has been shown to be effective in reducing recurrence rates and improving survival outcomes in patients with low-grade TCC. In this patient, intravesical BCG is the preferred management option due to the low risk of progression and the potential for organ preservation.

**Why Each Wrong Option is Incorrect**
**Option A:** Just follow up is not an appropriate management strategy for a patient with a histologically confirmed TCC, as there is a risk of recurrence and progression. Regular follow-up is essential, but it does not address the underlying disease process.

**Option B:** Intravesical chemotherapy may be used in some cases of TCC, but it is not the preferred treatment for low-grade papillary TCC with no muscle invasion. Chemotherapy may be associated with higher toxicity and lower efficacy compared to BCG.

**Option D:** Cystectomy (surgical removal of the bladder) is a more aggressive treatment option that is typically reserved for high-grade TCC or muscle-invasive disease. In this case, the tumor is low-grade and non-muscle invasive, making cystectomy an unnecessary and potentially morbid treatment option.

**Clinical Pearl / High-Yield Fact**
The European Organization for Research and Treatment of Cancer (EORTC) guidelines recommend the use of intravesical BCG as the first-line treatment for non-muscle-invasive TCC with high-grade or recurrent disease. This highlights the importance of BCG in the management of TCC and the need for careful patient selection and follow-up.

**✓ Correct Answer: C. Intravesical BCG**