Immunohistochemical expression of CRX in extracranial malignant small round cell tumors.
Tumor-specific immunohistochemical markers are valuable in the differential diagnosis of malignant small round cell tumors (MSRCTs). The cone-rod homeobox-containing gene (CRX) is a transcription factor that is preferentially expressed in retinal photoreceptor cells. It has been shown that the CRX antibody is a good immunohistochemical marker to differentiate retinoblastoma from other intracranial MSRCTs. Outside of the central nervous system, however, the usefulness of CRX immunohistochemistry in establishing a diagnosis of metastatic retinoblastoma is uncertain, as the expression of CRX in primitive neuroectodermal tumor/Ewing sarcoma (PNET/ES), neuroblastoma, and other MSRCTs is unknown. Archival specimens from resections, core biopsies, and bone marrow biopsies of 41 neuroblastomas, 24 PNET/ES, 19 embryonal rhabdomyosarcomas, 17 alveolar rhabdomyosarcomas, 17 Wilms tumors, 14 desmoplastic small round cell tumors, 20 medulloblastomas, 9 pineal tumors, 17 melanocytic tumors (compound and Spitz nevi), and 8 retinoblastomas were immunostained for CRX. All retinoblastomas had strong diffuse nuclear immunoreactivity for CRX; 8 of the 20 medulloblastomas showed strong nuclear immunoreactivity either in occasional clusters of tumor cells or in rare single scattered tumor cells; 3 of the 9 pineal tumors showed strong nuclear immunoreactivity in approximately 40% to 50% of the tumor cells. Neuroblastomas, PNET/ES, embryonal rhabdomyosarcomas, alveolar rhabdomyosarcomas, Wilms tumors, desmoplastic small round cell tumors, and melanocytic tumors were all negative. Scant nonspecific cytoplasmic staining was observed in some tumors, mostly PNET/ES. These findings suggest that CRX is a useful marker to discriminate metastatic retinoblastoma from other, more common, MSRCTs of childhood.
Department of Pathology, Children's Hospital Boston, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA.
Jefferson
J
Terry
Monica L
ML
Calicchio
Carlos
C
Rodriguez-Galindo
Antonio R
AR
Perez-Atayde
D014408:Biomarkers, Tumor / Q000032:analysis*; D058405:Desmoplastic Small Round Cell Tumor / Q000175:diagnosis / Q000378:metabolism; D003937:Diagnosis, Differential; D018398:Homeodomain Proteins / Q000032:analysis* / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D009362:Neoplasm Metastasis / Q000175:diagnosis*; D009369:Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D009447:Neuroblastoma / Q000175:diagnosis / Q000378:metabolism; D018242:Neuroectodermal Tumors, Primitive / Q000175:diagnosis / Q000378:metabolism; D019572:Retinal Neoplasms / Q000175:diagnosis; D012175:Retinoblastoma / Q000175:diagnosis / Q000556:secondary; D012208:Rhabdomyosarcoma / Q000175:diagnosis / Q000378:metabolism; D015534:Trans-Activators / Q000032:analysis* / Q000096:biosynthesis; D009396:Wilms Tumor
D014408:Biomarkers, Tumor; D018398:Homeodomain Proteins; D015534:Trans-Activators; C109288:cone rod homeobox protein