Brucellosis is the most common zoonotic disease in Saudi Arabia, with an incidence rate of 50–500 cases per 1,000,000 population (1, 2). Incidence of brucellosis among children ranges from 20% to 30% among endemic regions (2). It is a multisystem infection with broad-spectrum clinical manifestation. The most frequently involved sites are the musculoskeletal system, spleen, liver, and bone marrow (3, 4). Anemia, leukopenia, and pancytopenia are common hematological manifestations of brucellosis (4). Although there are few case reports of thrombotic microangiopathy associated with brucellosis, none have performed an ADAMTS13 (A Disintegrin and Metalloprotease with ThromboSpondian Type 1 motifs 13) test. This report presents the case of a 9-year-old boy with acquired thrombotic thrombocytopenic purpura (TTP) from brucellosis infection with an undetectable ADAMTS13 assay.

A 9-year-old previously healthy Syrian boy was admitted with a 1-day history of epistaxis, hematemesis, hematuria, and melena associated with periumbilical abdominal pain. He also has been complaining of pallor, decreased activity and appetite, and weight loss for a month prior to his presentation. A week before his admission, there was a noticeable increase in his pallor. Upon presentation, he was hypoactive, pale, and jaundiced. He was normothermic and hemodynamically stable. System examination revealed hepatosplenomegaly small palpable lymph node in the supraclavicular and inguinal region. The remainder of his physical examination was unremarkable.

His initial Laboratory tests at admission showed a picture of bi-cytopenia in the form of anemia and thrombocytopenia. Platelet 11 × 10⁹/L (normal range: 150–400 × 10⁹/L); hemoglobin 97 mg/L (normal range: 113–150 mg/J); white blood cells 10.2 × 10⁹/L (normal range: 4–12 × 10⁹/L); and reticulocyte counts 2.45% (normal range: 0.5%–1.5%). Peripheral blood smear showed red blood cell fragmentation (Schistocytes) at 1.45%, and white blood cells, mainly neutrophilia, displayed reactive changes in forms of toxic granulation.

Lactate dehydrogenase was 1,021 U/L (normal range: 125–220 U/L); aspartate aminotransferase 46 IU/L (normal range: 5–34 U/L); alkaline phosphatase 143 IU/L (normal range: 156–369 U/L); total bilirubin 41.3 µmol/L (normal range: ∼20.5 µmol/L); and direct bilirubin 12.7 µmol/L (normal range: ∼8.6 µmol/L). Blood urea nitrogen and creatinine were within normal limits. Urinalysis showed hematuria and hemoglobinuria. Coagulation screening tests were within the normal range; fibrinogen level was decreased to 1.72 g/L (normal range: 1.5–4.1 g/L); Coombs test was negative.

Initially, the patient was diagnosed with atypical idiopathic thrombocytopenic purpura (ITP) and treated with Intravenous Immunoglobulin (IVIG) 1 g/kg. He received two doses of IVIG without response, and his Hgb and platelet counts declined further.

In order to rule out bone marrow infiltration, bone marrow aspirations (BMA) and biopsy were performed. The preliminary report of the BMA did not suggest malignancy; however, it showed megakaryocytes which is suggestive of immune destruction. Therefore the patient was started on a six days trial of pulse steroid therapy (intravenous methylprednisolone 2 mg/kg/day divided twice a day), with no improvement in Hgb or platelet count. The final result of BMA revealed peripheral destruction of blood cells, indicating microangiopathic hemolytic anemia (MAHA), likely TTP, congenital or acquired due to an immune reaction to ADAMTS-13; this diagnosis was supported by repeated peripheral blood smear showing Schistocytes fragments of red blood cells >2.5% (Normal range <1.5%), accordingly a five days trial of fresh frozen plasma transfusion was initiated, in which the patient showed improvement in LDH and platelet levels.

In addition, bone marrow biopsy results showed morphologic evidence of frequent small epithelioid non-necrotizing granuloma. Considering that this is a nonspecific finding that could be attributed to various etiologies, including infections (viral, bacterial, and tuberculosis), infiltrating diseases such as sarcoidosis, and malignancies, further investigation has been pursued. Viral surveillance, including EBV, CMV, and HIV were negative. QuantiFERON-TB Gold was negative. Abdominal ultrasound and computerized chest and abdominal tomography (CT) scan showed splenomegaly with no significant lymph node enlargement. Since Brucella is endemic in Saudi Arabia and the patient had recently consumed a significant amount of unpasteurized goat milk and cheese, brucella titers were sent, and the result showed Brucella abortus 1:5,120 (normal range: <1:160), and Brucella melitensis 1:20,480 (normal range: <1:160).

A combination of Doxycycline (5 mg/kg/day orally twice a day) and Rifampin (20 mg/kg/day orally twice a day) antimicrobial therapy was commenced for a total of 6 weeks (42 days) to treat brucellosis. Once starting the anti-brucellosis management, the patient did not require further FFP transfusion. The ADAMTS-13 essay result showed: extremely low ADAMTS-13 activity, which was found at 0.02 IU/ml (normal range: 0.40–1.30 IU/ml), with an antigen assay below the detection level of 0.01 IU/ml (normal range: 0.41–1.41 IU/ml); and anti-ADAMTS-13 antibodies were detected at high concentrations of >95 IU/ml (>15 IU/ml is considered positive). All these findings, along with the presentation of thrombocytopenia and hemolysis, are specific to acquired TTP.

Several days following the commencement of antibiotic therapy, the platelets count and hemoglobin levels recovered to the normal range (Figure 1), while the lactate dehydrogenase levels decreased substantially to a normal level.

The infection of brucellosis, a zoonotic disease caused by a gram-negative coccobacilli bacterium named Brucella, is considered endemic in Central Asia, the Mediterranean, and the Middle East. In most cases, its presenting symptoms are non-specific, such as fever, malaise, weight loss, and hepatosplenomegaly, making its diagnosis challenging; however, systemic involvement is not uncommon and can affect multiple systems including Central Nervous System, cardiac, Musculoskeletal, and less commonly pulmonary (1, 3).

Hematological manifestations commonly accompany this infection, mainly in the form of anemia, leukopenia & thrombocytopenia (4, 5). These hematological disturbances are attributed to hypersplenism, hemophagocytosis & bone marrow infiltration of brucella granulomas (5, 6). Fewer reported cases in the literature were linked to hemolysis. These include MAHA and, to a lesser extent, autoimmune hemolytic anemia (7). MAHA is a descriptive term for non-immune hemolytic anemia resulting from intravascular RBC fragmentation, producing schistocytes on the peripheral blood smear. TTP is one of the disorders that presents with MAHA and thrombocytopenia. It is characterized by a deficiency of von Willebrand factor (VWF) cleaving protease (ADAMTS13), which is responsible for the cleavage of ultra-large VWF multimers. When ADAMTS13 is deficient, the accumulation of such ultra-large multimers leads to microvascular thrombosis, thrombocytopenia, and hemolytic anemia (8). In addition to bleeding, its’ clinical presentation might accompany gastrointestinal, neurological, and renal involvement. The severity of this illness varies from severe life-threatening to milder vague presentation.

TTP is classified as hereditary or, more commonly, acquired. The inherited form of TTP is caused by homozygous or compound heterozygous mutations of ADAMATS 13 that are inherited as recessive traits (9). In contrast, acquired TTP is secondary to the development of inhibitory autoantibodies against ADAMTS 13. These antibodies are believed to act by neutralizing ADAMTS 13 activity or, less commonly, by enhancing its clearance (8). These antibodies were identified in almost all (94%–97%) patients with acquired TTP (10). ADAMTS13 assay and its association with TTP had been linked to multiple infectious etiologies, including influenza, malaria, particularly falciparum, HIV, and Brucella infections (11–13). Although Brucella is not a well-known infectious etiology for TTP, few reports in the literature suggest their association (Table 1) (14–21). Most of these cases were reported in adults, primarily from countries with endemic diseases, such as Turkey. The usually reported presentation was non-specific symptoms like fever, malaise, and headache, with purpuric rash being the most common sign of bleeding. Some cases have reported accompanying epistaxis, and only four cases were reported to have neurological manifestations (16–18, 21).

Our patient had severe epistaxis, hematemesis, and hematuria. His presentation was unique, with only two reported cases of significant epistaxis and gross hematuria (17, 21). Compared to most cases found in literature, no purpura was noted in our patient. The severity and acuity of his bleeding and hematological profile were concerning for primary hematological disease. The brucellosis diagnosis was not considered until the BMA revealed granuloma. Our patient was diagnosed with Brucella 2 weeks after admission and started on antibiotics. Our patient's presenting symptoms differ from most reported cases, as his symptoms favoured brucellosis, which led to early consideration of Brucella and administration of antibiotics within the first weeks of admission (7). The assay results obtained from our patient confirmed a low ADAMTS 13 level and the presence of antibodies, which are not previously reported in the literature to the best of our knowledge.

Despite several case reports suggesting a potential association between brucellosis and TTP, our case is the first to be confirmed by ADAMTS 13 assay. Although rare, this disease manifestation is so severe that we suggest lowering the threshold for Brucella evaluation for TTP patients, particularly in areas where Brucella is prevalent. The use of the ADAMTS 13 assay in such cases should be considered when possible to confirm the diagnosis.