Paraneoplastic leukocytosis secondary to carcinosarcoma: a report of two cases and literature review

Neutrophilia is an increase in the number of neutrophils over 7.5×103/µL. An increase in leukocytes over 50×103/µL is called a leukemoid reaction; and when it is associated with a solid tumor, it is considered a paraneoplastic syndrome called paraneoplastic leukemoid reaction (PLR). It is a very rare clinical condition and it is very unusual for it to be associated with carcinosarcoma. We present two cases of a leukemoid reaction observed in the Medical Oncology Department of the University Hospital of Salamanca between May and September 2023. The main objectives of our article are to describe the unusual appearance of paraneoplastic leukocytosis at the diagnosis of carcinosarcoma carcinosarcoma, explain in a detailed way its diagnostic procedure and to show the poor prognosis to which it is associated.