Table 1.

Demographics and secondary diseases in LGL leukemia.

Category	Further details and references
Age at diagnosis
Typically in the 6th decade of life	Median 60 years, rare pediatric, <25% of adult patients <50 years old [1]; 66.5 years median age, 14% <50 years [9]; median age 67 [8]
Time to treatment
Treatment at diagnosis is ~60% [12]	45% required systemic therapy (of these, 60% within 1 month of dx, 37% between 1–6 months of dx) [9]
Survival rate
~10 years	Median overall survival 9–10 years [9]; overall survival 10 years ~70% [1]
Incidence
Overall incidence: 2–5% North America and Europe, 5–6% Asia; roughly same incidence for males and females [1]	Overall average=0.2 cases per 1,000,000 (US population) Male-to-female ratio 1.05 with females diagnosed at a younger age (65 vs. 68 years) [9] 53% male, 47% female [8] Aggressive NK-LGL leukemia incidence is mainly in Asia and affects younger patients [1]
Ethnicity incidence
Not significantly different among ethnic groups	White 0.2, Black 0.14, American Indian/Alaska Native 0.24, Asian/Pacific Islander 0.15 [9]
Subtypes of LGL leukemia
T-cell (αβ or γδ phenotype)	85% of cases, majority are TCRαβ+ phenotype [1] 85% of cases [9] 91% of cases [8]
NK-cell, chronic	<10% of cases [1] 6% of cases [8]
NK-cell, aggressive	<5% of cases [1]
Secondary diseases
Most common autoimmune disease: Rheumatoid arthritis (RA)	10–18% [1] 17–36% [14] 11–36% [12, 13]
Rarer occurring autoimmune diseases: systemic lupus erythematosus (SLE), Felty’s syndrome, Sjogren’s syndrome, and others.	Occasional (<1%) [1] Sjogren 2–27%, Felty 40%, SLE rare; thyroid disorders 2–3% [14] Case report [13]
Blood-related autoimmune diseases: pure red cell aplasia (PRCA), acquired autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), and others	5%; PRCA 5–27%, AIHA 5–9% [1] PRCA 5%, AIHA <2% [14] PRCA 5%, AIHA 3%, ITP rare [12, 13]
Blood disorders/bone marrow failure: aplastic anemia, myelodysplastic syndrome, B-cell malignancies	AA: Occasional association [12, 73] MDS: 3–10% [1]; <4% myelodysplasia [12, 13] B-cell malignancies: 5% [1]; 5–7% [13]; 27–43% [34]; 5–7% [12]
Other: Pulmonary artery hypertension	<1%[1]; Rare [13]