Multilocular cystic renal cell carcinoma

Multilocular Cystic Renal Cell Carcinoma (MCRCC), also known as multilocular cystic nephroma or multilocular clear cell renal cell carcinoma, is a rare subtype of renal cell carcinoma (RCC) characterized by the presence of multiple cysts. The World Health Organization (WHO) classifies it under the group of clear cell renal cell carcinomas. MCRCC is known for its generally favorable prognosis and distinct histopathological features compared to other types of RCC.

Epidemiology

MCRCC is a rare entity, accounting for approximately 1-2% of all renal cell carcinomas. It has a predilection for males and is most commonly diagnosed in adults, with a peak incidence in the fifth to seventh decades of life. Unlike other forms of RCC, MCRCC is less commonly associated with genetic syndromes and risk factors such as smoking and obesity.

Pathophysiology

The exact pathogenesis of MCRCC is not well understood. Histologically, it is characterized by the presence of multiple non-communicating cysts separated by septa that are composed of fibrous tissue. The cysts are lined by clear cells with minimal atypia, which are similar to the cells seen in conventional clear cell renal cell carcinoma. However, the absence of solid areas and the presence of a multilocular appearance distinguish MCRCC from other RCC subtypes.

Clinical Features

Patients with MCRCC typically present with nonspecific symptoms or are asymptomatic. The tumor is often discovered incidentally during imaging studies performed for unrelated reasons. When symptoms do occur, they may include flank pain, abdominal mass, and hematuria. Due to its benign behavior, MCRCC generally has a favorable prognosis, with a low potential for metastasis and recurrence after surgical resection.

Diagnosis

The diagnosis of MCRCC is primarily based on imaging studies, including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). These modalities can help differentiate MCRCC from other cystic renal lesions by demonstrating the multilocular nature of the cysts and the absence of solid components. However, definitive diagnosis often requires histopathological examination of the surgical specimen.

Treatment

The mainstay of treatment for MCRCC is surgical resection. Nephron-sparing surgery, such as partial nephrectomy, is preferred due to the benign nature of the tumor and the desire to preserve renal function. Radical nephrectomy may be considered in cases where partial nephrectomy is not feasible. Follow-up after surgery is important to monitor for recurrence, although the risk is low.

Prognosis

The prognosis of MCRCC is generally excellent, with high survival rates after surgical resection. The benign histological features and low potential for metastasis contribute to the favorable outcome. Regular follow-up is recommended to detect any recurrence early, although this is rare.