Blood clots in spleen were unusual first sign in case of acquired TTP
Young man with immune-mediated TTP made rapid recovery after diagnosis
A young man with unusual blood clots in the spleen was ultimately diagnosed with immune-mediated thrombotic thrombocytopenic purpura (TTP) — also known as acquired TTP — by Mayo Clinic doctors despite his symptoms developing in an atypical order.
It took eight trips to an emergency department, and multiple imaging and other tests, for the man to be diagnosed with immune-mediated TTP. However, once diagnosed, he recovered rapidly with a combination of treatments that involved plasma exchange, the approved TTP medication Cablivi (caplacizumab), prednisone, and rituximab, according to researchers.
Doctors at the Mayo Clinic in Rochester, Minnesota, described the man’s case in a letter to the editor published in Mayo Clinic Proceedings. The letter was titled “Arterial Thrombotic Event in Thrombotic Thrombocytopenic Purpura Predating the Development of Microangiopathic Hemolytic Anemia and Thrombocytopenia.”
“This case reflects an atypical presentation of TTP,” the team wrote, noting that the blood clots in the spleen “predated the development of thrombocytopenia by [four] weeks.” Thrombocytopenia is marked by lower than normal amounts of platelets — cell fragments that help blood clot — in the blood.
In TTP, blood clots form in small vessels and restrict blood supply to the body’s organs, leading to a wide range of possible symptoms. In immune-mediated TTP, this is caused by antibodies that mistakenly attack ADAMTS13, an enzyme that prevents blood clots from forming where they are not needed.
Getting a diagnosis required 8 trips to the emergency department
This report details the case of a man in his mid-30s who sought emergency department treatment for pain in the upper left side of his abdomen. Imaging of his abdomen showed an acute ischemic infarct of the spleen, which means tissue death in his spleen due to a lack of blood supply. The testing also revealed an enlarged spleen. An ultrasound of his heart did not show any problems.
A Holter monitor, which records the heart’s rhythm, did not detect atrial fibrillation — an irregular and often very rapid heart rhythm — which is a common cause of blood clots. Blood tests at this stage were mostly normal, and the man was treated with blood thinners: first heparin and aspirin, then apixaban.
In the following month, he returned to the emergency department six times with palpitations, chest pain, and headaches. These symptoms were attributed to anxiety, and his platelet counts were normal. Platelets were first found to be low at his sixth visit, four weeks after his initial emergency department visit.
Two days later, the man returned with weakness in his right leg and trouble speaking. An MRI of the brain showed infarcts in the left frontal lobe and cerebellum — regions that control cognition and movement. A scan of his abdomen revealed a new infarct in his left kidney.
Blood tests now showed more severe thrombocytopenia and elevated bilirubin, a sign of increased red blood cell destruction. His ADAMTS13 activity was less than 5%, confirming the diagnosis of immune-mediated TTP.
Man’s platelet counts returned to normal within 1 week after treatment
Treatment for the man’s acquired TTP included plasma exchange — a procedure that removes disease-causing antibodies from the blood — along with Cablivi to prevent platelets from forming blood clots. He was also given the corticosteroid prednisone to suppress the immune system, and rituximab to deplete B-cells, the immune cells that produce antibodies.
Within a week of treatment, his platelet counts returned to normal numbers, and almost two weeks later, ADAMTS13 activity was restored, the researchers reported.
This case is unusual, the team noted, because blood clots first occurred in the spleen, outside the brain, and before his platelets dropped to low numbers — all atypical for this type of TTP.
The reasons for this delay are not fully understood but may involve differences in blood flow in different organs, according to the researchers. In patients with unexplained blood clots, doctors should consider checking blood counts and looking for signs of thrombotic microangiopathy, or blood clots in small blood vessels, the team noted.
“Currently, we do not have conclusive evidence to recommend routine ADAMTS13 testing for every patient with a [blood clot of unknown origin in an artery]. We hope that this case contributes to the growing body of evidence that [thrombotic microangiopathy] can occur in the context of normal platelet counts,” the investigators concluded.
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