Papillary renal cell carcinoma (PRCC) is a malignant, heterogeneous tumor originating from renal tubular epithelial cells of the kidney, which comprises approximately 10-15% of all kidney neoplasms. Based on its morphological features, PRCC can be classified into two main subtypes, which are type 1 (basophilic) and type 2 (eosinophilic).As with other types of renal cell cancer, most cases of PRCC are discovered incidentally without showing specific signs or symptoms of cancer. In advanced stages, hematuria, flank pain, and abdominal mass are the three classic manifestation. While a complete list of the causes of PRCC remains unclear, several risk factors were identified to affect PRCC development, such as genetic mutations, kidney-related disease, environmental and lifestyle risk factors. For pathogenesis, type 1 PRCC is mainly caused by MET gene mutation while type 2 PRCC is associated with several different genetic pathways. For diagnosis, PRCC is detectable through computed tomography (CT) scans or magnetic resonance imaging (MRI), which commonly present a small homogeneous hyposvascular tumor. Nephrectomy or partial nephrectomy is usually recommended for PRCC treatment, often accompanied with several targeted molecular therapies to inhibit metastatic spread. PRCC patients are predominantly male with a mean age of 52–66 years. When compared to conventional clear cell renal cell carcinoma (RCC), the prognosis of non-metastatic PRCC is more favorable, whereas a relatively worse outcome was reported in patients with metastatic disease. Globally, the incidence of PRCC ranges between 3,500 to 5,000 cases, while it greatly varies depending on gender, age, and race/ethnicity.
Prognosis
The five-year survival rate of PRCC has been reported as 82-90%, which is slightly higher than that of other kidney cancers. The reduced survival rate has been positively correlated to several factors, which are high nuclear grade and stage, vascular invasion, DNA aneuploidy, and more. Patients with type 1 PRCC have significantly improved survival rates than those with type 2, which is a reflection of its lower TNM stage with a well-encapsulated tumor. Compared to other common types of RCC, PRCC exhibits a relatively lower risk of tumor recurrence and cancer-related death after nephrectomy. Specifically, the cancer-specific survival rate at five years following surgery with PRCC has reached up to 91%, while clear cell RCC and chromophobe RCC were 72% and 88%, respectively. Epidemiology
Among different histologic subtypes of RCC, PRCC is the second most predominant type and accounts for 10-15% of all renal tumors. In the case of the United States, it is estimated that the incidence of PRCC will rise to 3,500 to 5,000 cases annually. Generally, PRCC is more prevalent among men than women, while the reported sex ratio (M: F) varies from 1.8:1 to 3.8:1. The mean age at presentation is identified as 52–66 years old; however, no statistically significant difference was found in the incidence of PRCC between the younger (< 40 years) and older adult groups (>40 years). In terms of racial variation, several studies have proven that people with African or Afro-Caribbean ancestry tend to have higher chances of being diagnosed with PRCC.