Results
During a 10-year period, 3,760 bone marrow samples were evaluated. The samples were made up of ALL, acute myeloid leukemia (AML), and neuroblastoma diagnoses at 35% (n=1,298), 9% (n=344), and 2% (n=77), respectively.
During this time, nine samples (0.24%) in six unique patients, all with malignancy, were identified to have BMN (Table 1). The mean age was seven years (11 months - 18 years). Four patients were female and two were male. One patient had relapsed/refractory B-ALL, one had AML, three had neuroblastoma, and one had diffuse large B-cell lymphoma (DLBCL). Eight bone marrow evaluations were performed prior to chemotherapy and one was performed after reinduction therapy.
Hematologic laboratory findings were obtained from eighth encounters. The mean hematologic laboratory findings were leukocytes of 6.9 x 109/L (range 0.3-13.3 x 109/L), hemoglobin of 9.7 g/dL (range 8.3-11.5 g/dL), and platelets of 336 x 109/L (38-667 x 109/L). Severe neutropenia and thrombocytopenia were evidenced only in the patient with refractory B-ALL. The patient with AML initially had normal peripheral blood counts when the first bone marrow sample was obtained, however with subsequent assessments there was gradual development of leukopenia and neutropenia. Neither of the patients with leukemia had peripheral blasts at the time of bone marrow evaluation. All patients with neuroblastoma had normal blood counts at the time of bone marrow assessment and the majority had extensive tumor involvement in the marrow ranging from 60% to >95%. Three of our patients required repeat bone marrow evaluations due to either an inability to establish a diagnosis, or a suboptimal initial sample.
In regard to systemic symptoms, all patients had musculoskeletal symptoms manifested as lower extremity and/or back pain. This was the most common initial complaint and prompted an expanded workup, with five of six patients undergoing imaging. Plain radiographs were unremarkable; however, other imaging modalities including bone scan, magnetic resonance imaging (MRI), and computed tomography were abnormal demonstrating increased uptake in the bone marrow of long bones, lytic lesions and/or sclerotic bone.
Follow up was documented in the electronic records for all patients treated in our institution. The patient with refractory B-ALL died from vancomycin-resistant enterococcus sepsis. Four patients are in remission after chemotherapy treatment (2-5 years) (Table 1). Repeat bone marrow examinations showed no evidence of necrosis on follow up assessment for both the AML (end of induction) and neuroblastoma (4-7 months of treatment) patients.