Neuronal differentiating features are present in most neuroblastomas; therefore, the histological diagnosis of neuroblastoma is unequivocal in the vast majority of the patients. In the case of a completely undiffer-entiated histological pattern, other small blue round cell tumors need to be ruled out; those include Ew-ing's sarcoma and other peripheral neuroectodermal tumors (PNET), rhabdomyosarcoma (RMS), desmo-plastic small round cell tumor (DSRCT) and malignant non-Hodgkin's lymphoma (NHL). These tumors do not excrete elevated catecholamine metabolites and are not MIBG avid (Ewing's/ PNET tumors may demonstrate faint MIBG uptake). The locations of tumors may help to discriminate further [bone involvement in Ewing's sarcoma, ribs and thoracic wall in PNETs (Askin tumors), main soft tissue mass in rhabdomyosarcoma, peritoneal implants in DSRCT, and frequent lymphoblastic bone marrow infiltration in NHL]; however, one has to be reminded that dumbbell tumors with an intrathoracic/intraabdom-inal spindle mass extending into the intraspinal space has been described for (extraskeletal) Ewing's sarcoma as well as for NHL and for soft tissue sarcomas. Immunohistochemistry using a panel of antibodies is necessary to make the correct differential diagnosis in those cases. The histological diagnosis of neuroblastoma in an adult patient presenting with catecholamine-negative, MIBG-negative primary tumor and metastases only to the lung should raise suspicion. In the near future, the characteristic differences of gene expression between the small blue round cell tumors may help further distinguish these tumor types (Khan et al. 2001). Before small round blue cell tumor gene chips become readily available, already established tumor-specific translocations, such as EWS-FLI1 (t11;22) (q24;q12) in the Ewing sarcoma family of tumors, PAX3-FKHR (t2;13) (q35;q14) in alveolar rhabdomyosarcoma, the WT1-EWS (t11;22) (p13;q12) in DSRCT, and the cmyc gene involving translocation (t8;14) (q24;q32) in Burkitt's lymphoma,may be helpful for differential diagnosis.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.