Table 6. Clinical vignettes illustrating... | American Society of Hematology

Table 6.

Clinical vignettes illustrating specific situations that can be encountered in patients with ET

Case	Situation
Case 6: Familial ET	A 26-y-old woman (proband in Figure 2) was diagnosed with JAK2 (V617F)-mutant ET after the incidental discovery of thrombocytosis. During the diagnostic workup (described in Table 2), we learned that 1 uncle was followed in another hospital because of ET. Considering the familial history, we decided to perform a CBC count and to screen for JAK2 (V617F) in all family members. The patient’s father had thrombocytosis and carried JAK2 (V617F): a bone marrow biopsy confirmed a diagnosis of ET (Figure 2). The remaining relatives had normal CBC counts and no evidence of JAK2 (V617F).
Case 7: A woman with ET becomes pregnant	A 35-y-old woman followed at our Department for a low-risk JAK2 (V617F)-mutant ET (PLT count at diagnosis equal to 726 × 10⁹/L, no history of thrombosis or major bleeding) became pregnant. Three years before, she had had a pregnancy complicated by severe preeclampsia that required preterm delivery at the 30th week. Before conception, she was treated with low-dose aspirin: when she became pregnant, we added LMWH to low-dose aspirin throughout pregnancy. This woman had a normal delivery.
Case 8: ET complicated by SVT	A 40-y-old woman was diagnosed with low-risk JAK2 (V617F)-mutant ET in 2005 (PLT count at diagnosis equal to 706 × 10⁹/L, no history of thrombosis) and was given low-dose aspirin. She had a history of recurrent miscarriages (4 previous events before diagnosis of ET). Two years later, she was admitted to our hospital because of abdominal pain; abdomen ultrasound and computed tomography scan showed massive splenic-portal thrombosis. Positivity for lupus anticoagulant was found, and anticoagulation with LMWH was started, followed by warfarin. Because this was now a high-risk condition, we started a cytoreductive treatment with hydroxyurea. After 6 y of hydroxyurea, we enrolled this patient into a clinical trial on the use of the JAK inhibitor ruxolitinib for treatment of SVT associated with MPNs. Under ruxolitinib treatment, she obtained complete normalization of the CBC and complete regression of splenomegaly; reduction of spleen volume was confirmed with sequential magnetic resonance imaging.
Case 9: ET resistant to conventional treatments and responsive to ruxolitinib	A 25-y-old man was referred to our Department in 2005 because of extreme thrombocytosis (PLT counts steadily >1500 × 10⁹/L). At that time, we made a diagnosis of JAK2 (V617F)-negative ET and, because of the extreme thrombocytosis and the young age, we started a treatment with interferon α. Twelve months later, interferon treatment was discontinued because of lack of hematologic response, and hydroxyurea was started. Despite a dose of 2 g per day, this treatment was also ineffective and PLT count increased to >2000 × 10⁹/L. This patient was therefore enrolled into a clinical trial on the use of ruxolitinib⁸⁴: his PLT count decreased to about 600 × 10⁹/L, and remained stable around this value. This patient was recently found to carry a CALR mutation.

Case	Situation
Case 6: Familial ET	A 26-y-old woman (proband in Figure 2) was diagnosed with JAK2 (V617F)-mutant ET after the incidental discovery of thrombocytosis. During the diagnostic workup (described in Table 2), we learned that 1 uncle was followed in another hospital because of ET. Considering the familial history, we decided to perform a CBC count and to screen for JAK2 (V617F) in all family members. The patient’s father had thrombocytosis and carried JAK2 (V617F): a bone marrow biopsy confirmed a diagnosis of ET (Figure 2). The remaining relatives had normal CBC counts and no evidence of JAK2 (V617F).
Case 7: A woman with ET becomes pregnant	A 35-y-old woman followed at our Department for a low-risk JAK2 (V617F)-mutant ET (PLT count at diagnosis equal to 726 × 10⁹/L, no history of thrombosis or major bleeding) became pregnant. Three years before, she had had a pregnancy complicated by severe preeclampsia that required preterm delivery at the 30th week. Before conception, she was treated with low-dose aspirin: when she became pregnant, we added LMWH to low-dose aspirin throughout pregnancy. This woman had a normal delivery.
Case 8: ET complicated by SVT	A 40-y-old woman was diagnosed with low-risk JAK2 (V617F)-mutant ET in 2005 (PLT count at diagnosis equal to 706 × 10⁹/L, no history of thrombosis) and was given low-dose aspirin. She had a history of recurrent miscarriages (4 previous events before diagnosis of ET). Two years later, she was admitted to our hospital because of abdominal pain; abdomen ultrasound and computed tomography scan showed massive splenic-portal thrombosis. Positivity for lupus anticoagulant was found, and anticoagulation with LMWH was started, followed by warfarin. Because this was now a high-risk condition, we started a cytoreductive treatment with hydroxyurea. After 6 y of hydroxyurea, we enrolled this patient into a clinical trial on the use of the JAK inhibitor ruxolitinib for treatment of SVT associated with MPNs. Under ruxolitinib treatment, she obtained complete normalization of the CBC and complete regression of splenomegaly; reduction of spleen volume was confirmed with sequential magnetic resonance imaging.
Case 9: ET resistant to conventional treatments and responsive to ruxolitinib	A 25-y-old man was referred to our Department in 2005 because of extreme thrombocytosis (PLT counts steadily >1500 × 10⁹/L). At that time, we made a diagnosis of JAK2 (V617F)-negative ET and, because of the extreme thrombocytosis and the young age, we started a treatment with interferon α. Twelve months later, interferon treatment was discontinued because of lack of hematologic response, and hydroxyurea was started. Despite a dose of 2 g per day, this treatment was also ineffective and PLT count increased to >2000 × 10⁹/L. This patient was therefore enrolled into a clinical trial on the use of ruxolitinib⁸⁴: his PLT count decreased to about 600 × 10⁹/L, and remained stable around this value. This patient was recently found to carry a CALR mutation.