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Schwannoma with features mimicking neuroblastoma: report of two cases with
immuno-histochemical and ultrastructural findings.
J Clin Pathol. 1998 Nov;51(11):842-5.
OBJECTIVE: A study of
two cases of a rare variant of benign schwannoma showing areas mimicking
neuroblastoma/peripheral primitive neuroectodermal tumour (PNET). METHODS:
Sections of formalin fixed, paraffin embedded specimens were studied by
tinctorial stains and immunohistochemistry, and the tissue retrieved from
formalin was examined by electronmicroscopy in one case. RESULTS: The
tumours were small and subcutaneous. Both showed features of benign
schwannoma; one had a multinodular plexiform pattern. In addition,
rosette-like structures consisting of collagenous cores surrounded by small
round cells or slightly larger epithelioid cells were present. Tumour cells
were positive for S100 protein, Leu7, and in one case GFAP, but were
negative for neurofilament protein, synaptophysin, and MIC2. Type IV
collagen surrounded individual cells. Electronmicroscopy in case 2 confirmed
schwannian features (lamina, processes) and failed to show features of
neuroblastoma (neuroendocrine granules). CONCLUSIONS: Benign schwannomas may
contain rosette-like structures mimicking neuroblastoma/PNET. The techniques
used confirmed schwannian differentiation only and eliminated neuroblastoma/PNET.
These uncommon variants should be recognised by practising histopathologists
to avoid erroneous diagnoses and inappropriate treatment.
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