Role of immunocytochemistry, electron microscopy, and DNA analysis in fine-needle aspiration biopsy diagnosis of Wilms' tumor

Abstract

We reviewed the cytologic features and results of ancillary studies in eight fine‐needle aspiration biopsies (FNAB) performed by posterior approach in 8 patients with unresectable Wilms' tumor (WT). Chemotherapy was given following the FNAB diagnosis of WT, which was confirmed subsequently by histologic examination of surgically resected specimens. Indications for FNAB included: unresectable tumor, bilateral disease, initial presentation with metastatic disease, uncertainty regarding tumor site, and documentation of recurrence. Cytologic examination revealed blastemal cells (8/8 aspirates), spindle cells (3/8 aspirates), and epithelial differentiation or tubules (3/8 aspirates). There was no cytologic evidence of anaplasia in any of the cases. Immunocytochemical studies on cell blocks and/or smears showed cytokeratin positivity in 5/8 and vimentin positivity in 5/5 of the aspirates in which these studies were performed. Focal positivity for neuron‐specific enolase (NSE) was seen in 3/3 aspirates. Stains for actin and leukocyte‐common antigen were negative (0/3 and 0/2 aspirates, respectively). DNA ploidy analysis of the aspiration material by flow cytometry revealed near‐diploid populations in three aspirates. Electron microscopic findings helpful for diagnosis included: cell junctions, microvilli, flocculent basement membrane‐like material, cilia, autophagolysosomes, and lack of neuroectodermal differentiation. Diagnostic morphologic pitfalls for an incorrect diagnosis of neuroblastoma included nuclear molding (all aspirates), pseudorosette formation (one aspirate), and focal NSE positivity (3/3 aspirates). None of the tumors showed anaplasia on histologic examination. Cytologic recognition of the triphasic cellular components of WT (blastemal cells, spindle cells, and epithelial cells) can be helpful for a correct diagnosis; however, in 5/8 aspirates in this study, only the blastemal component was present. In these cases, immunocytochemical stains and electron microscopy proved useful in arriving at a correct FNAB diagnosis of WT. However, NSE positivity can be a pitfall for a diagnosis of neuroblastoma if the radiologic, clinical, and other cytologic features are not clearly delineated. Presence of cytokeratin and vimentin positivity would be helpful in the diagnosis of WT in such instances. Diagn Cytopathol 1996; 14:101–107. © 1996 Wiley‐Liss, Inc.

Diagnostic value of tissue polypeptide-specific antigen (TPS) in neuroblastoma and Wilms' tumour

“…Reports on clinically useful markers are not available. NSE (neuron-specific enolase) is useful in the initial screening for neuroblastoma, but the finding of elevated serum NSE levels does not exclude the diagnosis of Wilms' tumour (Pritchard et al, 1987), which is also well demonstrated immunohistochemically (Ellison et al, 1996).…”

“…Cytokeratin expression has been described mainly for cells of epithelial origin. The cytokeratin phenotype is well described in C) Cancer Research Campaign 1998 fetal kidney and is thought to be similar in the tubules of nephroblastoma (Giovagnoli et al, 1994;Ellison et al, 1996;Sainio et al, 1997). Only a few investigators have reported high serum TPS levels in cytokeratin-negative tumours (Norton et al, 1987;Ramaekers et al, 1988;Liu et al, 1992).…”

The cytological diagnosis of paediatric renal tumours

“…A diagnosis of anaplasia on cytology is made when a smear shows extremely large hyperchromatic blastemal cells three times the size of the surrounding blastemal cells coupled with brisk atypical mitosis (fig 2D). A potential limitation of FNAC of Wilms’ tumour is the inability to extensively sample a large mass and thereby to detect anaplasia1 and to distinguish focal from diffuse anaplasia.…”

“…Needle aspirates can easily be fixed in Karnosky or Universal fixative and the sediments can be processed for examination of specific ultrastructural features. Electron microscopy is particularly useful in identifying neuroblastoma and differentiating it from a Wilms’ tumour 1. While cell processes, dense-core granules and neurotubules are features that indicate a neuroblastoma, Wilms’ tumour reveals cell junctions, microvilli, flocculent basement membrane-like material, cilia and autophagolysosomes 1.…”

“…Electron microscopy is particularly useful in identifying neuroblastoma and differentiating it from a Wilms’ tumour 1. While cell processes, dense-core granules and neurotubules are features that indicate a neuroblastoma, Wilms’ tumour reveals cell junctions, microvilli, flocculent basement membrane-like material, cilia and autophagolysosomes 1. Similarly, RTK, PNET/ES and the newly described translocation associated renal cell carcinomas show unique ultrastructural features that will aid in their diagnosis.…”