Case Presentation: 59 year-old male with history of hypertension, presented with right arm weakness and slurred speech for 15 minutes. He reported feeling difficulty grabbing items while at the grocery store with his cousin and after starting to slur his words, EMS was called. Upon exam in the emergency department, he regained full strength in his right arm, but speech remained slurred. He also started experiencing tingling/numbness in both arms. Physical exam was significant for decreased strength in the right upper extremity and speech was slow, but fluent. He was able to name, repeat, and follow commands, but had minor word finding difficulty and global speech delay. Significant labs included an elevated troponin to 85 ng/L. EKG was concerning for new ST elevation on V3 and hyperacute T waves on lateral leads. Initial CTH was negative for acute ischemic or hemorrhagic changes. While awaiting MRI Brain, the patient developed severe non-radiating substernal chest pain with diaphoresis and altered mental status. A rapid response was called and further labs obtained at the time showed an interval increase in the troponin to 3000 ng/L and a platelet count of 1000 x 10^9/L. The patient was started on a heparin drip and taken to the CCU for close neurologic monitoring. The patient then reported bilateral total vision loss concerning for bilateral amaurosis fugax. The heparin drip was stopped and repeat CTH remained negative for acute findings. Urgent ophthalmology consult was also obtained, but no retinal hemorrhage was observed. MRI brain without contrast was expedited and showed recent bilateral infarcts in the right and left parietal lobes and the left frontal lobe. Hematology was consulted for possible essential thrombocytosis and the patient was started on hydroxyurea with improvement in platelet count and symptoms. Following stabilization of the patient, further testing to determine the etiology was performed including JAK2 and BCR ABL. JAK2 was found to be positive. This led to the diagnosis of multifocal bilateral hemispheric strokes and Type II NSTEMI secondary to essential thrombocytosis.
Discussion: Essential thrombocytosis is a chronic myeloproliferative neoplasm associated with clonal proliferation of platelets. The most common mutations seen in this condition include JAK2, CALR, and MPL. While patients can initially remain asymptomatic from essential thrombocytosis, they are at an increased risk for both thrombosis and abnormal bleeding. Symptoms include vasomotor manifestations such as headaches, visual disturbances, and dizziness, or with more severe complications including thrombotic or hemorrhagic events. Many clinicians may treat this like ischemic strokes, but the symptoms, including amaurosis fugax as seen in this patient, will not improve until aspirin and hydroxyurea are started to lower the platelet count.
Conclusions: This is a noteworthy case of JAK2 essential thrombocytosis in a classic patient. This patient’s initial platelet count was elevated to 1000 x 10^9/L on admission, so essential thrombocytosis should have been higher on the differential. This case highlights the need for broad initial differentials especially when it is not possible to localize a lesion to a specific vascular distribution. Since patients with essential thrombocytosis may initially be well-appearing before decompensating in the setting of multiple infarcts or sites of bleeding in several small vessel distributions, this condition is of practical importance in hospital medicine.