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Microgranular variant of acute promyelocytic leukemia in children
A Rovelli1, A Biondi, A Cantù Rajnoldi
1Clinica Pediatrica dell'Università di Milano, Ospedale San Gerardo, Monza, Italy.
Purpose:
The microgranular variant (M3v) of acute promyelocytic leukemia (APL) rarely has been reported in a pediatric series of acute nonlymphoblastic leukemia (AnLL). We reviewed the clinical and biologic features of childhood M3v cases in our AnLL series.
Patients And Methods:
From January 1970 to January 1991, 11 children with M3v were admitted and treated at our center. A diagnosis was made according to French-American-British (FAB) criteria. Morphologic examination, cytochemical analysis, and immunophenotyping were performed by a single pathologist. From January 1984, the diagnosis was confirmed by cytogenetic and, subsequently, by molecular analysis on frozen material.
Results:
In our series, the overall incidence of children with APL was unusually high, 31.2% of the AnLL and M3v constituted one case in every four cases of APL. Even restriction of the analysis to the time when either cytogenetic and DNA studies confirmed the diagnosis, the incidence did not change. The immunophenotype of M3v cases was identical to that described for the hypergranular type, but an unexpected association of CD2 with M3v was shown. The onset was characterized by marked hyperleukocytosis (median WBC count, 87 x 10(9)/L) unlike classic APL. Disseminated intravascular coagulation (DIC) was always present and severe. Hyperleukocytosis and DIC were responsible for the high incidence of deaths for hemorrhagic events in the first days after onset (eight of 11 patients).
Conclusions:
In our experience, for unknown reasons, M3v may occur in childhood more than generally was considered. The clinical course and prognosis seem worse in M3v than in typical APL cases.
Insights
The microgranular variant (M3v) of acute promyelocytic leukemia (APL) is more common in children than previously thought. This aggressive form of APL presents with high white blood cell counts and severe coagulation issues, leading to a worse prognosis.
Area of Science:
- Hematology
- Pediatric Oncology
Background:
- The microgranular variant (M3v) of acute promyelocytic leukemia (APL) is infrequently reported in pediatric acute nonlymphoblastic leukemia (AnLL) series.
- This study investigates the clinical and biologic characteristics of childhood M3v cases within a larger AnLL cohort.
Purpose of the Study:
- To determine the incidence and clinical features of M3v in pediatric AnLL.
- To compare the presentation and outcomes of childhood M3v with classic APL.
Main Methods:
- Retrospective review of 11 pediatric M3v cases diagnosed between 1970 and 1991.
- Diagnosis confirmed by French-American-British (FAB) criteria, morphology, cytochemistry, immunophenotyping, and later, cytogenetics and molecular analysis.
- Clinical data including hyperleukocytosis and disseminated intravascular coagulation (DIC) were analyzed.
Main Results:
- M3v accounted for a significant proportion (25%) of APL cases in this pediatric series.
- Immunophenotype was similar to hypergranular APL, with an unexpected CD2 association.
- Patients presented with marked hyperleukocytosis and severe DIC, leading to high early mortality from hemorrhage (8/11 patients).
Conclusions:
- Childhood M3v may be underrecognized.
- M3v cases exhibit a more severe clinical course and poorer prognosis compared to typical pediatric APL.