|What is Kidney Tumor?|
Different types of kidney tumors grow at different rates, have different prognoses and react differently to treatment. Determining the type of tumour is called histopathology.
BHD-related kidney cancer can be chromophobe, papillary or clear cell renal cell carcinoma (RCC). There have also been reports of mixed types as well as less common types. In the largest study to date of BHD-associated tumours, most were either solely benign oncocytomas or oncocytomas mixed with a type of cancerous kidney tumour. While among these types, chromophobe RCC is considered to have the best prognosis, followed by papillary and then clear cell RCC, recent studies have shown that the type of RCC is actually not as important as other variables, such as the stage and grade of the tumour. Therefore, it is important to be monitored regularly so that any potential cancer can be detected early.
Chromophobe kidney cancer is considered less aggressive than other forms of RCC, and is not usually metastatic in individuals affected by BHD, although metastatic cases have been reported. About 23% of BHD-related kidney tumours are chromophobe.
Although papillary renal cell carcinoma has been identified in BHD syndrome, it is not common. Papillary renal cell carcinoma (especially Type 2) can be aggressive and result in metastasis.
- Clear cell
Clear cell is one of the most common types of renal cell carcinoma. It is not generally considered common in families with BHD syndrome, though some doctors have recently identified more cases than expected. Clear cell carcinoma has also been identified in some hybrid tumours.
Oncocytomas are considered to be benign kidney tumours. While benign, oncocytomas can damage the kidneys as they may grow in places that might affect kidney blood flow or kidney function.
This type of tumour does not metastasise, or spread, to other parts of the body. About 3% of BHD-related kidney tumours were classified as oncocytic in the largest study of BHD kidney tumours to date.
- Hybrid tumours
Hybrid tumours are a mixture of two types. Several hybrids have been reported in BHD-related tumours, including oncocytic and chromophobe, and clear cell and chromophobe. In a study of 34 individuals with BHD-related kidney tumours, 67% of the tumours were identified as hybrid oncocytic/chromophobe.
- Other tumours
There have also been reports of other types of benign kidney tumours in BHD patients, such as renal angiomyolipomas, which are typically associated with tuberous sclerosis complex.