Case Presentation: A 56-year-old female presented to the ED complaining of epigastric abdominal pain for 5 days. Her past medical history was pertinent for a prior left upper extremity DVT. Her family history was positive for Factor V Leiden deficiency, for which she previously tested negative. She denied any pain radiation, nausea, vomiting, or change in bowel or bladder habits. She reported that 6 days prior she drove continuously for 10 hours. Routine lab work included a CBC, LFTs, and a lipase level. Her lab work was significant for a platelet count of 658, AST of 73, ALT of 74, ALP of 135, and a lipase of 688. CT of her abdomen/pelvis with contrast showed periportal edema. After being given IVF, she was discharged from the ED with subsequent resolution of symptoms. However, 2 days later she presented to her PCP complaining of similar abdominal pain warranting an MRI of the abdomen with contrast which was significant for thrombosed intrahepatic portal veins of the left and lateral right lobes. The PCP sent the patient to the ED, and additional blood work showed an increase in platelets to 803, ALT to 78, and ALP to 181. AST and lipase levels were normal during this visit. When reviewing the patient’s prior lab work, the patient had persistently elevated platelet counts. During her admission she was treated with heparin and morphine. After being discharged on apixaban, she received a positive JAK2-V6IF mutation result, consistent with a diagnosis of essential thrombocytosis (ET) which was the likely cause of both her previous upper extremity DVT and current portal vein thrombosis.
Discussion: Essential thrombocytosis is a myeloproliferative neoplasm that is characterized by elevated platelet levels. Assessing ET includes evaluating platelet count, obtaining a peripheral blood smear and a bone marrow biopsy, and having a positive gene mutation of JAK2, CALR, or MPL. Platelet counts in ET are typically higher than 450. Peripheral blood smear can show varying sizes of platelets from large to small, and bone marrow biopsy can show an abundance in largely sized megakaryocytes. Approximately 60-65% of ET cases will have a JAK2 mutation. About 9-22% of ET cases have already had episodes of thrombosis, such as TIAs, pulmonary embolism, or venous thrombosis. The International Prognostic Score of thrombosis calculates the severity of ET and therefore determines the course of treatment ranging from a cytoreductive agent in combination with systemic anticoagulation or low dose aspirin versus aspirin alone.
Conclusions: In patients with inexplicable persistent thrombocytosis, ET should be suspected warranting further workup. This case illustrates the importance of diagnosing ET because early recognition can lead to the appropriate treatment and prevent future complications including thrombosis.