Dear Editor:

A 57-year-old woman with a history of hypertension and breast cancer in complete remission was seen in late-March 2020 at the emergency ward in a private clinic with dry cough, anosmia, and dysgeusia. Physical examination found a low grade fever (37.8 °C) but was otherwise normal. A thoracic computerized tomography was normal, and a single nasopharyngeal swab (NPS) was reported as negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by a polymerase chain reaction (PCR)–based test. A complete blood work-up was normal except for mild lymphopenia (Day 1 on Table 1).

Table 1 Evolution of laboratory findings from the day of onset until end of plasma exchange therapy

Because of the pandemic state of SARS-CoV-2 and associated symptoms [1], the treating physicians considered the patient to have coronavirus disease 2019 (COVID-19) but with a false-negative result of the PCR NPS test. The patient was treated with lopinavir/ritonavir, hydroxychloroquine, and azithromycin. On the fifth day of treatment (Day 6 on Table 1) routine blood tests showed severe thrombocytopenia, moderate anemia with a normal reticulocyte count, and high serum lactate dehydrogenase (LDH) and bilirubin (Table 1). Treatment with methylprednisolone 1 mg/kg/24 h and intravenous immunoglobulin was added, but after no improvement in laboratory findings (Day 8 on Table 1), the patient was transferred to our institution for further management.

After initial clinical and laboratory work-up at our institution (Day 9 on Table 1), a diagnosis of autoimmune thrombotic thrombocytopenic purpura (TTP) was rapidly established, based on the presence of microangiopathic hemolytic anemia, severe thrombocytopenia, and very low activity (2%) of ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) in combination with the presence of an ADAMTS-13 inhibitor, which is an autoantibody to ADAMTS-13 [2, 3].

A NPS sample was retested in our center on admission and was negative for SARS-CoV-2, but serological tests were positive for SARS-CoV-2 IgG, thus confirming the past COVID-19 [4].

Treatment with plasma infusion on admission led to a rapid rise in the patient’s platelet count (Day 10 on Table 1). After placement of a central venous catheter, therapeutic plasma exchange was begun, with a favorable clinical and laboratory course over the next week (Day 17 on Table 1).

We present a case of acquired autoimmune TTP whose onset occurred immediately after COVID-19, since the patient was admitted for this latter infection with normal laboratory values.

Of course, this could be a mere coincidence rather than a causal relationship, owing to the very high incidence of SARS-CoV-2 infection [5].

As with other hematological disorders, the COVID-19 pandemic may change the way in which the approach to and management of patients may vary from the standard of care, as highlighted by the American Society of Hematology COVID-19 Resources Center (specific information on TTP can be found at https://www.hematology.org/covid-19/covid-19-and-ttp).