Detection of bone marrow metastases of neuroblastoma with immunohistochemical staining of CD56, chromogranin A, and synaptophysin.

Neuroblastoma is one of the most common solid tumors occurring in childhood. Bone marrow evaluation is an important part of clinical staging in neuroblastoma patients. In view of the difficulty of detecting neuroblastoma cells with conventional bone marrow aspirate smears and biopsy (BMB) and specimens in cases in which metastasis is not prominent, we propose the use of immunohistochemistry (IHC) as a potential diagnostic tool. We examined 116 BMB and 115 bone marrow clot (BMC) specimens from 60 newly diagnosed neuroblastoma patients for tumor cells. Neuroendocrine IHC markers, such as CD56, chromogranin A, and synaptophysin were applied to diagnose neuroblastoma. Eighteen out of the 60 patients (25.4%) displayed BM metastasis, as observed with conventional hematoxylin and eosin staining. IHC staining of BMC sections was generally more sensitive than that of BMB sections for tumor cell detection. We detected tumors in 5 and 7 additional hematoxylin and eosin-negative BMB and BMC sections, respectively, using CD56. Overall, CD56 or a combination of CD56 and chromogranin A was effective in detecting neuroblastoma cells. IHC analysis of BMB and BMC sections is warranted as a routine component of the diagnostic work-up of neuroblastoma to overcome discrepancies between routine smears and IHC stains.