Extramedullary hematopoiesis within cystic renal cell carcinoma with oncocytic and chromophobe cell types: A case report.

Extramedullary hematopoiesis (EMH) is a phenomenon in which hematopoietic cells are found in sites other than the bone marrow. It is usually observed in the liver and spleen but may occasionally be found within solid tumors. The current case report presents a 69-year-old female patient who presented with a renal cyst. Histopathological examination following surgical removal of the cyst revealed a lining of oncocytic- and chromophobe-type cells with capsular invasion and a mass forming EMH with evident bone trabeculae within the cyst wall. Circulating hematopoietic stem cells in the blood and their colonization within tissues is discussed in the present case report, emphasizing certain types of renal cell carcinoma.