Epidemiology of Hairy Cell Leukemia (HCL) and HCL-Like Disorders

Abstract

Hairy cell leukemia (HCL) is a very rare and well-defined entity that is characterized by the presence of hairy cells expressing the characteristic markers CD11c, CD25, CD103 and CD123 and in most cases by the presence of the BRAFV600E mutation. The incidence rate, directly adjusted to the 2000 United States standard population is estimated at 0.62 per 100 000 person-years (PA) in white men, 0.21 in black men, 0.20 in Asian men and 0.06 American Indian or Alaska native men. Based on the estimated 2019 leukemia incidence, of 61,780 in the United States, approximately 1,240 new HCL cases are expected per year, with only 60–75 new patients having a variant form of HCL each year. In France, the median age of patients at diagnosis is 63 years in men and 59 years in women. There is a strong male predominance, with a sex ratio of 5:1. HCL is a malignant disorder with a good prognosis, with a standardized average survival at 1 year and 5 years of 95% (95% CI: 91-97 for both). The etiology of HCL remains unknown. The risk of secondary cancers is high, especially that of another malignant hematologic disorder. This high risk justifies the need for prolonged hematological monitoring. HCL must be distinguished from other HCL-like disorders, including the variant form of HCL (HCL-V) or splenic diffuse red pulp lymphoma (SDRPL), warranting the development of international epidemiologic studies.

Immunophenotypic Analysis of Hairy Cell Leukemia (HCL) and Hairy Cell Leukemia-like (HCL-like) Disorders

“…Initially described in 1958 [ 1 ], HCL is a well-defined and distinct entity in the 4th revised 2017 classification of the World Health Organization (WHO) of hematopoietic and lymphoid tumors [ 2 ]. With approximately 1500 new yearly cases in Europe and the United States, HCL is four to five times more common in men than women [ 3 , 4 ]. The median age of patients at diagnosis is 63 years in men and 59 years in women [ 4 ].…”

“…With approximately 1500 new yearly cases in Europe and the United States, HCL is four to five times more common in men than women [ 3 , 4 ]. The median age of patients at diagnosis is 63 years in men and 59 years in women [ 4 ]. Patients present at diagnosis with splenomegaly, pancytopenia or infections.…”

Hairy Cell Leukemia and HCL-Like Disorders: Diagnosis and TreatmentLeuc閙ie �Tricholeucocytes et Autres Prolif閞ations �Cellules Chevelues: Diagnostic et Traitement

“…La leucémie à tricholeucocytes (LT) appelée aussi HCL (Hairy Cell Leukemia) représente moins de 1% de l'ensemble des hémopathies malignes (HM) et 2% de l'ensemble des leucémies [1][2][3][4]. Le nombre de cas incidents est de 1,500 en Europe [5], 300 en France [4] et de 1,100 aux Etats-Unis [6].…”

Deciphering Genetic Alterations of Hairy Cell Leukemia and Hairy Cell Leukemia-like Disorders in 98 Patients

“…Hairy cell leukemia (HCL) is a rare B-cell chronic lymphoproliferative disorder, with an incidence rate adjusted to the American population of 0.7/100,000 in males and 0.3/100,000 in females [1] and adjusted to the world population of 0.5 and 0.1/100,000 in France [2]. HCL is a well-defined entity characterized by the presence of hairy cells in the peripheral blood and/or bone marrow.…”