Familial hairy cell leukemia

Medical history, lifestyle, and occupational risk factors for hairy cell leukemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Little is known about the etiology of hairy cell leukemia (HCL), a rare B-cell lymphoproliferative disorder with marked male predominance. Our aim was to identify key risk factors for HCL.

METHODS

A pooled analysis of individual-level data for 154 histologically confirmed HCL cases and 8834 controls from five case-control studies, conducted in Europe and Australia, was undertaken. Age-, race and/or ethnicity-, sex-, and study-adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression.

RESULTS

The usual patterns for age and sex in HCL were observed, with a median age of 55 years and sex ratio of 3.7 males to females. Cigarette smoking was inversely associated with HCL (OR = 0.51, 95% CI = 0.37 to 0.71) with dose-response relationships observed for duration, frequency, and lifetime cigarette smoking (P(trend) < .001). In contrast, occupation as a farmer was positively associated with HCL (OR = 2.34, 95% CI = 1.36 to 4.01), with a dose-response relationship observed for duration (OR = 1.82, 95% CI = 0.85 to 3.88 for ≤ 10 years vs never; and OR = 2.98, 95% CI = 1.50 to 5.93 for >10 years vs never; P(trend) = .025). Adult height was also positively associated with HCL (OR = 2.69, 95% CI = 1.39 to 5.29 for upper vs lower quartile of height). The observed associations remained consistent in multivariate analysis.

CONCLUSIONS

Our observations of an increased risk of HCL from farming exposures and decreased risk from smoking exposures, independent of one another, support a multifactorial origin and an etiological specificity of HCL compared with other non-Hodgkin lymphoma subtypes. The positive association with height is a novel finding that needs replication.

Two new cases of familial hairy cell leukemia associated with HLA haplotypes A2, B7, Bw4, Bw6

Hairy cell leukemia (HCL) is a rare hematological disorder of unknown origin. Thirteen familial cases of HCL have been reported, with 28 relatives affected. Here we report 2 cases of HCL in a family associated with HLA haplotypes A2, B7 and Bw4/6.

Hairy cell leukemia: current concepts

Hairy cell Leukemia (HCL) is a chronic lymphoproliferative disorder that was characterized in the late 1950s. HCL is defined, according to the WHO classification, as a mature (peripheral) B-cell neoplasm (1). HCL accounts for between 2-3% of all leukemia cases, with about 600 new cases diagnosed in the U.S. each year (1). HCL occurs more commonly in males, with an overall male to female ratio of approximately 4:1. The median age of onset is 52 years. This disease is seen more commonly in Caucasians and appears to be especially frequent in Ashkenazi Jewish males, with rare occurrence in persons of Asian and African descents (1). Hairy cells are distinct, clonal B cells arrested at a late stage of maturation. They are small B lymphoid cells that possess oval nuclei and abundant cytoplasm with characteristic micro-filamentous ("hairy") projections. They strongly express CD103, CD22, and CD11c (2). These cells typically infiltrate the bone marrow, the spleen, and to a lesser extent the liver, lymph nodes, and skin. Many patients present with splenomegaly and pancytopenia. Other clinical manifestations include recurrent opportunistic infections and vasculitis. Historically, HCL was considered uniformly fatal (2). However, recent treatment advances, using purine analogues such as Cladribine and Pentostatin, led to a significant improvement in prognosis with achievement of high response rates and durable remissions (2).

Hairy cell leukemia in father and son

Hairy cell leukemia (HCL) is an uncommon B cell disorder, and familial HCL is rarely encountered among the first degree relatives of HCL patients. A father and son, both of whom developed hairy cell leukemia, is presented in this report. The HLA haplotype shared by the father and son was A2, B18, BW6, CW7, DR3, DR10, and DQ8. Among these haplotypes, HLA A2 and Bw6 have previously been reported.

Hairy cell leukemia in first cousins and review of the literature

Familial hairy cell leukemia (HCL) occurs rarely. So far, 26 familial instances of HCL (in 12 families) have been reported in the literature. The consistent human leukocyte antigen (HLA) linkage could not be established in most cases of familial HCL. History of exposure to organic chemicals or employment in woodworking or farming was noted in only two out of 11 affected families. We present two familial cases of HCL as well as a thorough literature review. An influence of HLA or farming themselves on a predisposition to HCL remains unproven but does not rule out an HLA-linked and as yet unidentified gene responsible for increased disease susceptibility. HCL in families is unlikely to be due to random patterning, but there are insufficient data so far to decisively incriminate either HLA-related or environmental causative factors.