Les auteurs rendent compte du cas d’un garçon de six ans qui a consulté en raison d’une hématurie macroscopique. Les examens ont démontré que l’étiologie de l’hématurie était une thrombopénie révélant une leucémie lymphoblastique aiguë. Un examen de la moelle osseuse a confirmé le diagnostic de leucémie. L’hématurie du patient s’est complètement résorbée après la transfusion de plaquettes. Bien que la thrombopénie soit un élément révélateur très courant de la leucémie lymphoblastique aiguë, l’hématurie macroscopique est extrêmement rare. Ainsi, il faut envisager une thrombopénie causée par la leucémie aiguë chez un patient qui consulte en raison d’une hématurie macroscopique.

A six-year-old boy presented to the emergency department with a two-day history of gross painless hematuria, vague abdominal pain, a 10-day history of fatigue and decreased appetite. Four weeks before admission he had experienced an upper respiratory tract infection. There was no recent history of trauma or use of any medication. There was no family history of hematuria or other renal diseases. Physical examination revealed mild pallor, bruising, tachycardia and splenomegaly. Urinalysis showed large amounts of red blood cells, and urine cultures failed to show any infection. A renal Doppler ultrasound did not reveal any renal, ureteric or bladder pathology.

A complete blood count (CBC) showed a hemoglobin level of 92 g/L, white blood cell count of 64.9×10⁹/L (blast cells 78%, neutrophils 1% and lymphocytes 15%) and a platelet count of 2×10⁹/L. Peripheral blood smear revealed abnormal lymphocytes (Figure 1). The international normalized ratio, the partial thromboplastin time and the fibrinogen level were all normal. Urate and lactate dehydrogenase levels were elevated, while the remaining biochemistry was normal. Bone marrow aspirate demonstrated 98% blast cells (Figure 2). Precursor B cell ALL was diagnosed, and the patient was started on a high-risk ALL protocol. Within two days of starting chemotherapy and after multiple platelet transfusions, his hematuria resolved.

Figure 1 Acute lymphoblastic leukemia. Peripheral blood of patient with one neutrophil and three lymphoblasts

Figure 2 Acute lymphoblastic leukemia. All cells in the bone marrow aspirate are lymphoblasts

A recent paediatric series (4) that consisted of 342 patients showed that the most common causes of gross hematuria included urethral irritation (19%), trauma (14%), urinary tract infection (14%), congenital urological anomalies (13%), urolithiasis (5%), bladder carcinoma (0.8%) and Wilms’ tumours (0.3%). No etiology was found in 34% of patients.

Coagulopathies, renal vein thrombosis and thrombocytopenia are less frequently the cause of hematuria in children. In destructive thrombocytopenias, hematuria is unusual. For example, in one series of 332 children with idiopathic thrombocytopenic purpura, only six children (1.8%) presented with hematuria (1). Bleeding, in general, can be the initial sign of childhood leukemias. It is usually caused by thrombocytopenia secondary to bone marrow infiltration, or it can be precipitated by disseminated intravascular coagulation. The latter is particularly common in children with acute promyelocytic leukemia (AML)-M3 and, to a lesser degree, in children with other subtypes of AML (AML-M4 or AML-M5) and T cell ALL (5). Hematuria is more common in AML-M4 and AML-M5 when hyperleukocytosis (white blood cell count greater than 100×10⁹/L) is present. Furthermore patients with these subtypes of AML are predisposed to renal vein thrombosis, which itself can cause gross hematuria (6).

ALL is the most common childhood cancer. The most frequent symptoms of ALL are attributed to cytopenias (fever and infections from neutropenia, pallor from anemia and bruising, petechiae and bleeding from thrombocytopenia). Thrombocytopenia is particularly common as a presenting feature of ALL, being present in two-thirds of cases at diagnosis. Yet, despite thrombocytopenia being so common in ALL, gross hematuria is extremely rare as a presenting feature. Five cases of childhood ALL presenting with gross hematuria have been reported in the literature. Hematuria was caused by leukemic infiltration of the urinary bladder (four of five cases) (2,7,8) and of the kidneys (one case) (3).

Paediatric nephrologists usually recommend a urine culture, serum creatinine determination and CBC in a child with gross hematuria (9). Early detection and prompt therapy of leukemia in this setting are essential to avoid lifethreatening complications (eg, renal failure).

In the presence of gross painless hematuria, a CBC and a blood smear should be performed, because thrombocytopenia potentially caused by acute leukemia may, in rare cases, be the underlying culprit.