Immunohistochemical study of
neuroblastomas, Ewing
sarcomas,
rhabdomyosarcomas, and Wilms
tumors demonstrate specific expression of
peripherin and
alpha-internexin in 20/22 and 6/22 cases of
neuroblastomas, respectively.
Microtubule-associated protein 1B (MAP 1B) was strongly and diffusely expressed in all 22 cases of
neuroblastomas, but was also focally or multifocally expressed in 9/12
rhabdomyosarcomas and also in the blastema and stroma of 8/11 Wilms
tumors. All
rhabdomyosarcomas strongly and diffusely express
nestin, but this marker was also expressed, multifocally, in 15/22
neuroblastomas and also in the blastema and stroma of all 11 Wilms
tumors. NeuN, a neuron-specific
nuclear protein, was expressed focally in 1 case of
neuroblastoma and diffusely in 2 other cases (3/22). Surprisingly, it was also focally expressed in 2/12
rhabdomyosarcomas. In contrast, all 7 cases of
Ewing sarcoma were negative for
peripherin, MAP 1B,
alpha-internexin, NeuN, and
nestin. Thirteen
neuroblastomas were also immunostained for neurofilaments,
tyrosinase, and
anaplastic lymphoma kinase 1 (ALK 1), and were found to be negative for these markers. Our results confirm that
peripherin and
alpha-internexin are
neuroblastoma markers useful for the differential diagnostic work-up of small round cell
tumors of childhood. Strong diffuse immunoreactivity for MAP 1B favors a diagnosis of
neuroblastoma, whereas strong diffuse immunoreactivity for
nestin favors a diagnosis of
rhabdomyosarcoma.