Olfactory neuroblastoma. An immunohistochemical, ultrastructural, and flow cytometric study

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Olfactory neuroblastoma is an uncommon neuroectodermal tumor originating in the upper nasal cavity.
• Its microscopic features are often heterogeneous, lacking clear prognostic indicators.
• Previous studies have not reliably linked morphology to patient outcomes.

Purpose of the Study:

• To investigate the immunohistochemical, ultrastructural, and DNA flow cytometric characteristics of olfactory neuroblastoma.
• To identify potential correlations between these features and patient survival rates.

Main Methods:

• Immunohistochemistry, electron microscopy, and DNA flow cytometry were performed on 26 olfactory neuroblastoma samples.
• Survival data were analyzed in relation to various clinicopathological and molecular variables.
• Tumor subtypes, marker expression (synaptophysin, neurofilament protein, beta-tubulin, chromogranin A, S-100, cytokeratin, EMA, p53), Ki-67 labeling index, ploidy, and S-phase fraction were assessed.

Main Results:

• Most tumors displayed features intermediate between paraganglioma (PG) and neuroblastoma (NB), with some showing ganglioneuroblastoma (GNB) or epithelial differentiation.
• Neuronal and neuroendocrine markers were frequently expressed, alongside S-100 protein in sustentacular cells (88%).
• Aberrant p53 expression (62%), high rates of polyploidy/aneuploidy (78%), and a wide range of Ki-67 LI (mean 7.4%) and S-phase fractions (mean 9.0%) were observed.

Conclusions:

• Olfactory neuroblastomas, while exhibiting PG/NB differentiation, lean towards PG-like features.
• Tumors can present with GNB and/or epithelial differentiation.
• Survival rates appear to correlate significantly with S-100 protein immunoreactivity and a low Ki-67 labeling index (<10%).