Appendix. Bone Marrow Aspirate Morphology
Bone marrow cell counts and cultures were performed on 54 of 63 collected marrow specimens. The 9 unevaluable samples were due to specimen clotting before cell counts and cultures could be performed and included three 1ml, three 5 ml and three 10 ml samples of which 6 samples were from 2 patients.
Evaluation of the available bone marrow core biopsy sections (see Table A.1) demonstrated that most bone marrow core biopsy sections showed normal morphology with cellularity within the expected range for age (70-95% cellularity), particularly in areas away from the sub periosteum where cellularity was characteristically lower than in the other areas of the marrow. There was progressive trilineage hematopoiesis with no morphologic abnormalities.
The myeloid to erythroid ratios were all within normal limits and varied from 2:1 to 4:1.
Megakaryocytes were adequate in all samples. Cortical bone (when present) and trabecular bone were also histologically evaluated. All samples showed histologically normal bone with bone marrow osteoclasts and osteoblasts evident in the tissue sections, as would be expected in pediatric patients. Two samples (patient 9 and patient 11) showed a relative decrease in bone marrow cellularity due to increased fat (25 and 15% cellularity, respectively) but were noted to be primarily subperiosteal marrow but were felt to have increased fat deposition though out the marrow in both patients. Additionally, focal fibrosis was also noted in patient 9. Another sample (patient 15) showed increased numbers of plump histiocytes, suggesting the possibility of a storage disorder, but normal trilineage hematopoiesis was present. The overall marrow cellularity was 95%, the estimated hematopoietic marrow component was 60% of cellularity in this patient, which is slightly lower than would be expected for age.
Table A.1. Bone Marrow Histology. M:E Ratio, myeloid to erythroid ratio.
Patient Average Cellularity (%)
M:E Ratio Megakaryocytes Abnormalities
1 95 4:1 adequate None
2 90 3:1 adequate None
3 85 3:1 adequate None
4 60 (10-80) 3:1 adequate None
5 40 (30-60) 4:0 adequate None
6 80 2:1 adequate None
7 40 4:1 adequate None
8 50 2:1 adequate None
9 25 (10-50) 1:1 adequate focal fibrosis
fatty change
10 95 3:1 adequate None
11 15 2:1 adequate fatty change
12 95 3:1 adequate None
13 75 2:1 adequate None
14 80 3:1 adequate None
15 95 3:1 adequate increased
histiocytes
16 75 3:1 adequate None
17 80 3:1 adequate None
18 95 1:2 adequate None
19 50 (30-70) 2:1 adequate None
20 60 (25-75) 3:1 adequate None
21 50 (20-60) 2:1 adequate None
