TEACHING POINTS
■ ITP is a diagnosis of exclusion. Laboratory abnormalities other than the platelet count widen the differential diagnosis.
■ Although most ITP cases are believed to be idiopathic, a small percentage of cases have identifiable etiologies. In this patient, quinine was thought to be the catalyst for disease development.
■ The natural history of ITP in adults is characterized by refractory or relapsing disease.
■ Repeated use of IVIG or anti-Rho in chronic ITP may allow patients to avoid splenectomy.
CASE
A 67-year-old female presented to the emergency department (ED) with a 12-hour history of oral petechiae and a single episode of epistaxis. In addition, she reported pruritus of the scalp and ears and episodes of melena and hematuria for 2 days preceding her arrival. She denied any current pain, although she reported two episodes of severe headache 1 week prior. She denied associated syncope, paresthesias, visual changes, or weakness. There had been no history of arthralgias, myalgias, or rashes. The patient reported recent travel to a rural region in the United States, but she had not noticed any ticks and/or bites. Review of systems was negative for fever, weight loss, nausea, vomiting, or diarrhea. Prescription medications included conjugated estrogens, levothyroxine, oxybutynin, and alendronate. In addition, the patient revealed periodic use of OTC nutritional supplements, including Ginkgo biloba, vitamin E, and red yeast rice. Two weeks before this illness, the patient had had leg cramps for which she had taken two quinine tablets of unknown quantity.
The medical history included hysterectomy secondary to cervical dysplasia, hemithyroidectomy, and bilateral mastectomy for fibroadenoma disease. Her mother and father had died secondary to multiple myeloma and prostate cancer, respectively. Her sister also died secondary to metastatic disease of unknown origin. There was no known family history of leukemia or platelet disorders. The patient had a 40-pack-year smoking history. She denied alcohol use.
Physical examination The patient was a well-nourished female in no acute distress, who was afebrile and normotensive. A 2-cm submucosal hemorrhagic lesion on the palate was noted, as well as multiple buccal petechiae and excoriations on the scalp. Diffuse petechiae were observed over the patient's legs, arms, and trunk. Multiple ecchymoses ranging from 1 to 5 cm in diameter were visible on the forearms and thighs. The abdomen was nontender and soft with no hepatosplenomegaly. No edema was observed in the extremities. There was no evidence of cervical or femoral lymphadenopathy. Cranial nerves were grossly intact. No focal neurologic deficits were noted.
Laboratory studies Initial laboratory results revealed a platelet count of 6×103/µL (reference range, 150-400×103/µL) with hemoglobin of 14.9 g/dL (reference range, 12.0-15.0 g/dL) and a hematocrit of 42.9% (35-45%), respectively. WBC count was 9×103/µL (3.2-9.8×103/µL). Results of a complete metabolic panel (CMP) were significant for a nonfasting glucose level of 156 mg/dL (reference range, less than 110 mg/dL). AST, ALT, total protein, albumin, and alkaline phosphatase levels were normal. Prothrombin time (PT), international normalized ratio (INR), and activated partial thromboplastin time (aPTT) were unremarkable. ESR was not elevated. Serum protein electrophoresis was normal.
Hospital course The patient was admitted to the hospital and underwent further laboratory and diagnostic testing. Fibrinogen, lactate dehydrogenase (LDH), haptoglobin, and serial PT/aPTT determinations were normal. HIV and hepatitis C virus (HCV) assay findings were negative. Results of a direct Coombs test were negative. Abdominal ultrasound found no sign of hepatosplenomegaly.
The diagnosis was immune thrombocytopenic purpura (ITP). The patient was treated aggressively with corticosteroids, platelet transfusion, IV immunoglobulin G (IVIG), and anti-Rho immunoglobulin. Within a few days, the platelet count had increased to 68×103/µL and all signs of hemorrhage ceased. There was no recurrence of headache or pruritus. The patient was discharged to outpatient therapy for continued monitoring of platelet levels.
Although the majority of ITP cases are believed to be idiopathic, a small percentage have identifiable etiologies. Given the temporal relationship between this patient's quinine dosing and development of ITP symptoms, she was advised to discontinue quinine permanently in the event that it was the causative variable.