The identification of neuroblastoma metastases to bone marrow (BM) is requisite in staging disease for risk‐adopted therapy. However, micrometastases were not elucidated fully.

Flow cytometry (FCM) with CD45/CD56/CD81 and reverse transcriptase‐polymerase chain reactions (RT‐PCR) for tyrosine hydroxylase (TH) transcripts were used to evaluate neuroblastoma in bilateral BM aspirates at diagnosis, BM autografts, peripheral blood stem cell (PBSC) collections, and CD34⁺ cell products of 27 children.

TH transcripts were amplified in histology‐negative (H⁻) BM specimens from seven patients (four patients with Stage 3 disease, two with Stage 4 disease, and one with Stage 4S disease), revealing a prevalence of submicroscopic metastasis. The median number of CD45⁻CD81⁺CD56⁺ cells in four H⁻ TH⁻ BM samples from two patients with Stage 1 and Stage 2 disease, respectively, was comparable to that encountered in 10 normal BM controls (0.003% [range, 0.002–0.004%] vs. 0.004% [0–0.008%], P = 0.724). In six H⁻ TH⁺ BM specimens from three patients whom were otherwise diagnosed with neuroblastoma Stage 3, 0.031% (0.009–0.06%) CD45⁻CD81⁺CD56⁺ cells were detected. Besides, 1.474% (0.088–3.009%) CD45⁻CD81⁺CD56⁺ cells were identified in four H⁻ TH⁺ BM specimens from two patients at Stage 4. TH transcripts were evident in four of five BM autografts and in 22 of 45 (48.9%) PBSC specimens. FCM demonstrated 0.018% and 0.049% CD45⁻CD81⁺CD56⁺ cells in two TH⁺ BM autografts, respectively. The number of CD45⁻CD81⁺CD56⁺ cells was higher in 19 TH⁺ PBSC specimens than in 20 TH⁻ PBSC specimens (0.026% [0.006–1.128%] vs. 0% [0–0.009%], P < 0.0001). CD34⁺ cell selection achieved 2.9 (2.1–3.5) log depletion of CD45⁻CD81⁺CD56⁺ cells in four manipulated products, rendering six of seven PBSC autografts TH‐free.

FCM in combination with RT‐PCR evaluated neuroblastoma micrometastasis and assessed the purity of hematopoietic autografts for transplant. However, the clinical relevance remains to be elucidated. Cancer 2003;97:2887–97. © 2003 American Cancer Society.

DOI 10.1002/cncr.11389