J Hematol

Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc

Journal website https://www.thejh.org

Original Article

Volume 10, Number 3, June 2021, pages 106-113

Essential Thrombocythemia in Children: A Retrospective Study

**Table 1.** Demographics and Clinical Characteristics (N = 28)
Variables of interest	Female	Male	Overall
^aTwenty patients (71.4%) were asymptomatic. ^bN = 18. Values are number (%) or median (minimum, maximum).
Patients, n (%)	19 (67.9)	9 (32.1)	28 (100.0)
Age at diagnosis (years)	10.0 (0.14, 13.8)	6.0 (at birth, 12.1)	8.8 (at birth, 13.8)
Height (cm)	127.0 (61.0, 163.0)	132.0 (70.0, 151.0)	130.0 (61.0, 163.0)
Weight (kg)	40.1 (6.7, 62.0)	28.7 (9.1, 41.0)	35.0 (6.7, 62.0)
Parental consanguinity, n (%)
Negative			12 (42.9)
Positive			16 (57.1)
Symptoms^a, n (%)
Headache			4 (14.3)
Bleeding			2 (7.1)
Vomiting			2 (7.1)
Abdominal pain			1 (3.6)
Nausea			1 (3.6)
Fatigue			1 (3.6)
Palpitation			1 (3.6)
Myopathy			1 (3.6)
Blood group^b, n (%)
A+			5 (27.8)
B+			1 (5.6)
O+			10 (55.6)
AB+			2 (11.1)

Table 1. Demographics and Clinical Characteristics (N = 28)

Variables of interest

Female

Male

Overall

^aTwenty patients (71.4%) were asymptomatic. ^bN = 18. Values are number (%) or median (minimum, maximum).

Patients, n (%)

19 (67.9)

9 (32.1)

28 (100.0)

Age at diagnosis (years)

10.0 (0.14, 13.8)

6.0 (at birth, 12.1)

8.8 (at birth, 13.8)

Height (cm)

127.0 (61.0, 163.0)

132.0 (70.0, 151.0)

130.0 (61.0, 163.0)

Weight (kg)

40.1 (6.7, 62.0)

28.7 (9.1, 41.0)

35.0 (6.7, 62.0)

Parental consanguinity, n (%)

Negative

12 (42.9)

Positive

16 (57.1)

Symptoms^a, n (%)

Headache

4 (14.3)

Bleeding

2 (7.1)

Vomiting

2 (7.1)

Abdominal pain

1 (3.6)

Nausea

1 (3.6)

Fatigue

1 (3.6)

Palpitation

1 (3.6)

Myopathy

1 (3.6)

Blood group^b, n (%)

A+

5 (27.8)

B+

1 (5.6)

O+

10 (55.6)

AB+

2 (11.1)

**Table 2.** Hematological Profile at Presentation
Parameters	Female (n = 19)	Male (n = 9)	Overall (n = 28)	P value
Values are median (minimum, maximum). WBC: white blood cell; Hb: hemoglobin; RBC: red blood cell; RDW: red cell distribution width; MCV: mean corpuscular volume; MPV: mean platelet volume; TIBC: total iron binding capacity; ESR: erythrocyte sedimentation rate; vWF: von Willebrand factor.
Platelets (× 10⁹/L)	826.0 (529.0, 2,003.0)	848.0 (625.0, 1,556.0)	846.5 (529.0, 2,003.0)	0.562
WBC (× 10⁹)	8.8 (4.1, 16.5)	9.6 (7.8, 15.9)	9.2 (4.1, 16.5)	0.172
Hb (g/L)	123.0 (101.0, 156.0)	126.0 (119.0, 152.0)	125.5 (101.0, 156.0)	0.383
RBC (× 10¹²/L)	4.4 (3.4, 5.6)	4.8 (4.5, 5.4)	4.6 (3.4, 5.6)	0.142
Reticulocyte count (%)	1.3 (0.9, 2.0)	1.1 (0.7, 1.7)	1.3 (0.7, 2.0)	0.267
Reticulocyte count (× 10⁹/L)	60.7 (35.0, 93.0)	55.9 (15.0, 99.0)	55.9 (15.0, 99.0)	0.764
RDW	14.0 (12.1, 18.0)	13.0 (8.0, 15.0)	13.8 (8.0, 18.0)	0.085
MCV	81.8 (70.0, 95.0)	80.2 (75, 88.4)	80.9 (70.0, 95.0)	0.322
MPV	9.1 (8.4, 10.5)	8.8 (5.5, 10.0)	9.0 (5.5, 10.5)	0.129
Serum ferritin	40.0 (18.0, 237.0)	34.4 (23.0, 101.0)	40.0 (18.0, 237.0)	0.809
TIBC	57.6 (49.9, 80.8)	59.0 (53.8, 67.0)	58.1 (49.9, 80.8)	0.945
ESR	13.0 (5.0, 222.0)	16.0 (10.0, 113.0)	14.5 (5.0, 222.0)	0.443
vWF antigen	1.51 (0.5, 60.0)	39.5 (0.8, 94.0)	1.51 (0.5, 94.0)	0.556
vWF assay	0.6 (0.4, 50.0)	20.5 (0.6, 49.0)	0.93 (0.42, 50.0)	0.556

Table 2. Hematological Profile at Presentation

Parameters

Female (n = 19)

Male (n = 9)

Overall (n = 28)

P value

Values are median (minimum, maximum). WBC: white blood cell; Hb: hemoglobin; RBC: red blood cell; RDW: red cell distribution width; MCV: mean corpuscular volume; MPV: mean platelet volume; TIBC: total iron binding capacity; ESR: erythrocyte sedimentation rate; vWF: von Willebrand factor.

Platelets (× 10⁹/L)

826.0 (529.0, 2,003.0)

848.0 (625.0, 1,556.0)

846.5 (529.0, 2,003.0)

0.562

WBC (× 10⁹)

8.8 (4.1, 16.5)

9.6 (7.8, 15.9)

9.2 (4.1, 16.5)

0.172

Hb (g/L)

123.0 (101.0, 156.0)

126.0 (119.0, 152.0)

125.5 (101.0, 156.0)

0.383

RBC (× 10¹²/L)

4.4 (3.4, 5.6)

4.8 (4.5, 5.4)

4.6 (3.4, 5.6)

0.142

Reticulocyte count (%)

1.3 (0.9, 2.0)

1.1 (0.7, 1.7)

1.3 (0.7, 2.0)

0.267

Reticulocyte count (× 10⁹/L)

60.7 (35.0, 93.0)

55.9 (15.0, 99.0)

0.764

RDW

14.0 (12.1, 18.0)

13.0 (8.0, 15.0)

13.8 (8.0, 18.0)

0.085

MCV

81.8 (70.0, 95.0)

80.2 (75, 88.4)

80.9 (70.0, 95.0)

0.322

MPV

9.1 (8.4, 10.5)

8.8 (5.5, 10.0)

9.0 (5.5, 10.5)

0.129

Serum ferritin

40.0 (18.0, 237.0)

34.4 (23.0, 101.0)

40.0 (18.0, 237.0)

0.809

TIBC

57.6 (49.9, 80.8)

59.0 (53.8, 67.0)

58.1 (49.9, 80.8)

0.945

ESR

13.0 (5.0, 222.0)

16.0 (10.0, 113.0)

14.5 (5.0, 222.0)

0.443

vWF antigen

1.51 (0.5, 60.0)

39.5 (0.8, 94.0)

1.51 (0.5, 94.0)

0.556

vWF assay

0.6 (0.4, 50.0)

20.5 (0.6, 49.0)

0.93 (0.42, 50.0)

0.556

**Table 3.** Patient’s Profile at Presentation, Treatment Regimen and Follow-Up
Patient	Gender	Age at diagnosis (years)	Symptoms at presentation	Platelets (× 10⁹/L)	WBC (× 10⁹/L)	JAK2	CALR	MPL	Treatment regimen	Symptoms during follow-up	Duration of follow-up (months)
WBC: white blood cell; JAK2: Janus kinase 2 gene; CALR: calreticulin; MPL: myeloproliferative leukemia virus oncogene; LDA: low-dose aspirin.
1	Male	6.6	None	625	7.8	Negative	Not done	Not done	None	None	54.9
2	Male	9.9	None	633	9.0	Negative	Not done	Not done	LDA	None	228.6
3	Male	1.2	None	686	12.9	Negative	Negative	Negative	None	None	72.2
4	Male	5.8	None	845	13.2	Negative	Not done	Not done	Anagrelide	None	192.0
5	Male	12.1	None	848	9.2	Negative	Not done	Not done	None	None	41.5
6	Male	5.8	None	1,012	8.9	Negative	Not done	Not done	None	None	41.9
7	Male	3.5	None	1,104	12.8	Negative	Negative	Negative	None	None	12.5
8	Male	10.0	None	1,403	9.6	Negative	Not done	Not done	Hydroxyurea	Azoospermia	87.0
9	Male	6.0	None	1,556	15.9	Not done	Not done	Not done	LDA	None	148.6
10	Female	3.6	None	529	7.9	Negative	Not done	Not done	None	None	178.7
11	Female	8.9	Weakness, fatigue, myopathy	529	8.7	Positive	Not done	Not done	LDA + hydroxyurea	None	218.2
12	Female	10.0	None	543	4.1	Positive	Not done	Not done	Platelets + LDA	Budd-Chiari syndrome	208.4
13	Female	11.6	None	625	9.8	Negative	Negative	Negative	LDA	Stroke	219.5
14	Female	1.6	None	654	16.5	Negative	Not done	Not done	None	None	20.0
15	Female	1.8	Headache, abdominal pain, nausea, vomiting	677	5.3	Negative	Negative	Negative	None	None	113.8
16	Female	13.8	Headache	750	11.3	Not done	Not done	Not done	LDA	None	101.9
17	Female	4.1	Palpitation	769	8.8	Negative	Negative	Negative	None	None	17.6
18	Female	3.1	Bleeding (spontaneous)	805	7.0	Negative	Not done	Not done	None	None	78.7
19	Female	10.0	None	826	6.5	Negative	Not done	Not done	None	None	65.6
20	Female	13.6	None	850	11.9	Negative	Not done	Not done	None	None	21
21	Female	8.8	None	898	11.3	Negative	Not done	Not done	None	None	71.0
22	Female	1.1	None	903	14.2	Negative	Not done	Not done	None	None	32.6
23	Female	11.0	None	1,205	6.5	Negative	Not done	Not done	LDA + hydroxyurea	None	74.5
24	Female	12.0	None	1,207	4.7	Negative	Not done	Not done	LDA	None	227.5
25	Female	11.0	Headache, vomiting	1,277	8.7	Negative	Not done	Not done	LDA + hydroxyurea	None	55.4
26	Female	1.0	Bleeding	1,401	14.0	Negative	Negative	Negative	LDA	Stroke	26.0
27	Female	11.1	None	2,003	9.2	Negative	Negative	Negative	LDA	None	12.1
28	Female	10.5	Headache	873	11.3	Negative	Negative	Negative	Hydroxyurea	None	32.9

Table 3. Patient’s Profile at Presentation, Treatment Regimen and Follow-Up

Patient

Gender

Age at diagnosis (years)

Symptoms at presentation

Platelets (× 10⁹/L)

WBC (× 10⁹/L)

JAK2

CALR

MPL

Treatment regimen

Symptoms during follow-up

Duration of follow-up (months)

WBC: white blood cell; JAK2: Janus kinase 2 gene; CALR: calreticulin; MPL: myeloproliferative leukemia virus oncogene; LDA: low-dose aspirin.

Male

6.6

None

625

7.8

Negative

Not done

None

54.9

Male

9.9

None

633

9.0

Negative

Not done

LDA

None

228.6

Male

1.2

None

686

12.9

Negative

None

72.2

Male

5.8

None

845

13.2

Negative

Not done

Anagrelide

None

192.0

Male

12.1

None

848

9.2

Negative

Not done

None

41.5

Male

5.8

None

1,012

8.9

Negative

Not done

None

41.9

Male

3.5

None

1,104

12.8

Negative

None

12.5

Male

10.0

None

1,403

9.6

Negative

Not done

Hydroxyurea

Azoospermia

87.0

Male

6.0

None

1,556

15.9

Not done

LDA

None

148.6

Female

3.6

None

529

7.9

Negative

Not done

None

178.7

Female

8.9

Weakness, fatigue, myopathy

529

8.7

Positive

Not done

LDA + hydroxyurea

None

218.2

Female

10.0

None

543

4.1

Positive

Not done

Platelets + LDA

Budd-Chiari syndrome

208.4

Female

11.6

None

625

9.8

Negative

LDA

Stroke

219.5

Female

1.6

None

654

16.5

Negative

Not done

None

20.0

Female

1.8

Headache, abdominal pain, nausea, vomiting

677

5.3

Negative

None

113.8

Female

13.8

Headache

750

11.3

Not done

LDA

None

101.9

Female

4.1

Palpitation

769

8.8

Negative

None

17.6

Female

3.1

Bleeding (spontaneous)

805

7.0

Negative

Not done

None

78.7

Female

10.0

None

826

6.5

Negative

Not done

None

65.6

Female

13.6

None

850

11.9

Negative

Not done

None

Female

8.8

None

898

11.3

Negative

Not done

None

71.0

Female

1.1

None

903

14.2

Negative

Not done

None

32.6

Female

11.0

None

1,205

6.5

Negative

Not done

LDA + hydroxyurea

None

74.5

Female

12.0

None

1,207

4.7

Negative

Not done

LDA

None

227.5

Female

11.0

Headache, vomiting

1,277

8.7

Negative

Not done

LDA + hydroxyurea

None

55.4

Female

1.0

Bleeding

1,401

14.0

Negative

LDA

Stroke

26.0

Female

11.1

None

2,003

9.2

Negative

LDA

None

12.1

Female

10.5

Headache

873

11.3

Negative

Hydroxyurea

None

32.9

**Table 4.** Clinical and Laboratory Features^a by *JAK2* Mutation Positivity (N = 26)
	JAK2+ (n = 2)	JAK2- (n = 24)	P value
^aValues are median (minimum, maximum) unless otherwise specified. ^bOverall follow-up time, median (minimum, maximum): 71.6 months (one visit, 228.6). JAK2: Janus kinase 2 gene mutation; WBC: white blood cell; Hb: hemoglobin; NOS: not otherwise specified.
Age at diagnosis (years)	9.4 (8.9, 10.0)	7.7 (at birth, 13.6)	0.745
Platelets (× 10⁹/L)	536.0 (529.0, 543.0)	849.0 (529.0, 2,003.0)	0.012
WBC (× 10⁹)	6.4 (4.1, 8.7)	9.2 (4.7, 16.5)	0.123
Hb (g/L)	128.5 (101.0, 156.0)	124.5 (110.0, 152.0)	1.000
Reticulocyte count (× 10⁹/L)	89.5 (86.0, 93.0)	55.9 (35.0, 99.0)	0.042
Follow-up time (months)^b	213.0 (208.4, 218.2)	60.5 (one visit, 228.6)	0.098
Symptoms (at presentations), n (%)			0.474
Asymptomatic	1 (50.0%)	18 (75.0%)
Symptomatic	1 (50.0%)	6 (25.0%)
Weakness	1 (33.3%)	None
Fatigue	1 (33.3%)	None
Myopathy	1 (33.3%)	None
Headache	None	3 (30.0%)
Vomiting	None	2 (20.0%)
Abdominal pain	None	1 (10.0%)
Nausea	None	1 (10.0%)
Palpitation	None	1 (10.0%)
Bleeding (spontaneous)	None	1 (10.0%)
Bleeding (NOS)	None	1 (10.0%)
Complications (during follow-up), n (%)			0.289
None experienced	1 (50.0%)	21 (87.5%)
With issues	1 (50.0%)	3 (12.5%)
Budd-Chiari syndrome	1 (100%)	None
Stroke	2 (66.6%)	None
Azoospermia	1 (33.3%)	None

Table 4. Clinical and Laboratory Features^a by JAK2 Mutation Positivity (N = 26)

JAK2+ (n = 2)

JAK2- (n = 24)

P value

^aValues are median (minimum, maximum) unless otherwise specified. ^bOverall follow-up time, median (minimum, maximum): 71.6 months (one visit, 228.6). JAK2: Janus kinase 2 gene mutation; WBC: white blood cell; Hb: hemoglobin; NOS: not otherwise specified.

Age at diagnosis (years)

9.4 (8.9, 10.0)

7.7 (at birth, 13.6)

0.745

Platelets (× 10⁹/L)

536.0 (529.0, 543.0)

849.0 (529.0, 2,003.0)

0.012

WBC (× 10⁹)

6.4 (4.1, 8.7)

9.2 (4.7, 16.5)

0.123

Hb (g/L)

128.5 (101.0, 156.0)

124.5 (110.0, 152.0)

1.000

Reticulocyte count (× 10⁹/L)

89.5 (86.0, 93.0)

55.9 (35.0, 99.0)

0.042

Follow-up time (months)^b

213.0 (208.4, 218.2)

60.5 (one visit, 228.6)

0.098

Symptoms (at presentations), n (%)

0.474

Asymptomatic

1 (50.0%)

18 (75.0%)

Symptomatic

1 (50.0%)

6 (25.0%)

Weakness

1 (33.3%)

None

Fatigue

1 (33.3%)

None

Myopathy

1 (33.3%)

None

Headache

None

3 (30.0%)

Vomiting

None

2 (20.0%)

Abdominal pain

None

1 (10.0%)

Nausea

None

1 (10.0%)

Palpitation

None

1 (10.0%)

Bleeding (spontaneous)

None

1 (10.0%)

Bleeding (NOS)

None

1 (10.0%)

Complications (during follow-up), n (%)

0.289

None experienced

1 (50.0%)

21 (87.5%)

With issues

1 (50.0%)

3 (12.5%)

Budd-Chiari syndrome

1 (100%)

None

Stroke

2 (66.6%)

None

Azoospermia

1 (33.3%)

None