Risperidone-induced thrombocytopenia in a case of psychosis and neuroendocrine tumor: A case report.

Abstract

Sir, Drug-induced thrombocytopenia can be caused by numerous medications,[1] but since thrombocytopenia can have many other causes, the diagnosis of drug-induced thrombocytopenia can easily be overlooked. It can have devastating, even fatal consequences that can usually be prevented simply by discontinuing the causative drug. It is therefore important that clinicians have a general understanding of this condition and the drugs that can cause it. Here, we present a case of thrombocytopenia induced by risperidone. Our patient, a 38-year-old male, previously healthy, not on any medication, was referred for a psychiatric consult for suspiciousness and odd behavior. Evaluation revealed delusions of persecution and reference for which he was started on tablet risperidone, 2 mg once daily. He started improving gradually; however on the 10thday of starting risperidone, he developed erythematous, painless rash, occurring in small discrete dots, not associated with itching or discharge, initially on the legs, rapidly spreading to the whole body within 2 days. Complete blood count revealed a platelet count of 30,000/mm3. After hematology consult, investigations (including peripheral blood smear, autoimmune profile, and bone marrow studies) were undertaken to find a possible cause for thrombocytopenia.[2] With a further drop in platelet count (20,000 mm3), the patient developed spontaneous gum bleeding. Risperidone, being the only recently introduced medicine, was suspected as a possible cause and was stopped. Platelet count improved rapidly on stopping risperidone, adding strength to the suspicion. Naranjo score of 7 indicated probable adverse drug reaction. Further investigations revealed neuroendocrine tumor of the intestines which was treated. Later, he was started on aripiprazole which was tolerated well and patient the responded favorably. Currently, he is asymptomatic, on medication. Written informed consent for publication of the case was obtained from the patient. George et al. critically analyzed reports of drug-induced thrombocytopenia and identified 85 medications for which a cause-and-effect relationship was considered to be “definite” (58 agents) or “probable” (27 agents) on the basis of clinical criteria.[1] According to their criteria, risperidone falls in the category of “probable” drug causing thrombocytopenia.[1] In general, a patient takes the sensitizing drug for about 1 week before presenting with petechial hemorrhages and ecchymoses. Severely affected patients (platelet count <20,000 mm3) may have florid purpura and bleeding manifestations. Upon stopping causative medication, symptoms usually resolve within 1 or 2 days, and the platelet count returns to normal in less than a week.[3] To our knowledge, there are only two published cases of thrombocytopenia associated with the use of risperidone.[456] In this case, we concluded that the decrease in platelets occurred due to risperidone since there was a chronological relationship between risperidone administration and emergence of the thrombocytopenia. Mechanism by which drugs produce thrombocytopenia is antibody mediated, either autoantibodies or naturally occurring antibodies, modulated by the drugs.[3] To the authors' knowledge, there are no reports of neuroendocrine tumors causing thrombocytopenia. Since risperidone is a commonly prescribed antipsychotic, known to be safe, awareness of this side effect and periodic blood profile monitoring may be beneficial for patients. Further research needs to be undertaken to explore this association. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.