Ultrastructural characterization of poorly differentiated rhabdomyosarcomas

The role of nuclear morphometry in prediction of prognosis for rhabdomyosarcoma in children

AIMS

To determine whether nuclear morphometry can be used in pretreatment diagnostic procedures to guide the therapy of childhood rhabdomyosarcoma (RMS).

MATERIALS AND METHODS

Biopsy specimens obtained from 108 patients with rhabdomyosarcoma aged between 1 and 217 months treated in 12 paediatric oncology departments in Poland were evaluated. There were 65 (60.2%) specimens of embryonal rhabdomyosarcoma (RME), 32 (29.6%) of alveolar RMS (RMA) and 11 (10.2%) cases of undifferentiated RMS (RMU). The clinical data from all analysed patients were evaluated. Nuclear morphometry was performed semiautomatically on haematoxylin-eosin-stained sections using the MultiScan v.8.08 Computer Scanning System and an Olympus BX 50 microscope with a x 40 magnification lens.

RESULTS

In the RMA subtype cells with spindle-shape nuclei were less common (P = 0.013) and cell nuclei were generally more round in comparison with RME (P = 0.033). The clinical outcome was better if the nuclei seen in biopsies of RMS were more spindle-shaped (event-free survival 0.51 and 0.23, respectively; P = 0.04) or more cells with spindle-shaped nuclei were observed (event-free survival 0.5 and 0.28, P = 0.035). RME patients with small nuclei had a better outcome then patients with large nuclei (P = 0.014). In the RMA/RMU group, patients with small tumour cell nuclei had a worse prognosis than patients with larg tumour cell nuclei (P = 0.046).

CONCLUSIONS

Nuclear morphometry is a useful tool in the assessment of children with RMS. Additionally, certain morphometric parameters could be easily applied in a selection of patients with good prognosis.

Special techniques in diagnostic electron microscopy

The power of electron microscopy as a diagnostic tool can be amplified considerably by the application of ancillary preparative and analytic methods. Subcellular chemistry and structure can be examined by various forms of microprobe analysis and by special staining methods, including cytochemical, immunocytochemical, and negative staining. Qualitative ultrastructural examination can be augmented by morphometric analysis. Correlative microscopic survey methods can be used as a means of targeting ultrastructural investigations. This article provides an overview of the use of these special techniques in the diagnosis and classification of tumors and other selected pathologic processes.

Differentiating small round cell sarcomas of the soft parts by an innovative immunogold labeling method: an ultrastructural study

A new immunoelectron microscopy procedure was developed by remaking the fixed-frozen tissue specimens into LR White resin blocks suitable for postembedding colloidal gold immunolabeling, and used to examine 16 cases of small round cell soft tissue sarcomas. In rhabdomyosarcoma, ultrastructural double-immunogold staining demonstrated a coexpression of muscle specific actin and desmin in the same tumor cell. In both Ewing's sarcoma and peripheral neuroepithelioma, the heterogeneous expression of MIC2 gene product (p30/32MIC2) in each tumor cell was demonstrated as well. In peripheral neuroepithelioma, the colloidal gold immunolabeling for neurofilament demonstrated the intermediate filaments surrounding microtubules. The procedure for ultrastructural colloidal gold immunolabeling using fixed-frozen tissue is thus considered to be useful not only for tumor diagnosis, but also for investigating various subcellular structures.