Amando Peydro-Olaya

Peripheral neuroectodermal sarcoma of soft tissue (peripheral neuroepithelioma): A pathologic study of ten cases with differential diagnosis regarding other small, round-cell sarcomas

Peripheral neuroepithelioma of soft tissue belongs to the group of peripheral neuroectodermal tumors (PNETs), but because of its clinical, biological, and morphological characteristics, it differs from other small, round-cell sarcomas that appear in children (neuroblastoma) or in the thoracopulmonary region (Askins tumor) and bone (peripheral neuroectodermal sarcoma of bone). We report ten new cases of such PNET variety, based on their histologic, immunohistochemical, and electron microscopic findings. In all of these cases, the clinicopathologic correlations demonstrated high malignancy, with an ominous outcome in nine cases. The mean age of the patients was 32.6 years and there was a clear male predominance (eight men, two women). Histologically, the presence of Homer-Wright rosettes is mandatory for diagnosis, being complemented with positive immunohistochemistry for several neural immunomarkers using paraffin-embedded material. Neuron-specific enolase, E-36, HNK-1, and chromogranin neural markers proved to be positive in a high number of cases, but other markers (S-100 protein, synapto-physin, GFA protein, and neurofilaments [70 kilodalton]) were absent. Electron microscopy confirmed the presence of neural structures, both by scanning and transmission electron microscopy.

Small round blue cell sarcoma of bone mimicking atypical Ewing's sarcoma with neuroectodermal features. An analysis of five cases with immunohistochemical and electron microscopic support.

Ewings sarcoma (ES) of bone may occasionally display rosette‐like textures mimicking Homer‐Wright ones, as seen in neuroectodermic neoplasms (neuroblastoma, peripheral neuroepithelioma). Of a group of 39 cases of ES, reviewed with electron microscopic study, the authors have isolated five atypical ES, which historically also possessed neuroectodermic traces. These tumors were composed of small round blue cells with rosette‐like figures and cytoplasmic glycogen. The immunohistochemical analysis showed positivity for neuron‐specific enolase (NSE) as well as for HNK‐1 (leu‐7) monoclonal antibody. Electron microscopic examination confirmed the tumor cell as being of small round type, with a dense chromatine pattern and the presence of isolated dendritic processes, as well as synaptic‐like buttons; intermediate filaments, neurotubuli, and dense‐core neurosecretory granules also were seen. Moreover, in two cases basement‐like condensations surrounded some cells. Scanning electron microscopic study in one case confirmed the presence of rosette‐like figures and cell elongations with short dendritic projections of the cytoplasm. Clinically and radiologically these cases showed features similar to ES of bone; one case, located in the chest wall, had a local relapse after treatment, with the histologic features of a pleomorphic neuroblastoma. The authors conclude that these tumors resemble closely immature neuroepithelioma of soft tissue but, being primary to bone, are superimposable on those described as “neuroectodermal tumors of bone.”

Does malignant small round cell tumor of the thoracopulmonary region (Askin tumor) constitute a clinicopathologic entity? An analysis of 30 cases with immunohistochemical and electron-microscopic support treated at the Institute Gustave Roussy.

The morphology and clinical outcome of 30 patients with malignant small round cell tumors located in the thoracopulmonary region (Ask in tumor) are reported. Histologically, all tumors had similar patterns, with small round‐to‐oval cells and a lobulated stroma. Immunohistochemical analysis always resulted in positive staining for one or several neural markers. No significant differences were found compared with the immunomarkers in 26 typical Ewings sarcomas located outside the thoracic wall. In three specimens, electron microscopy confirmed the presence of membrane‐bound neurosecretory granules. It was confirmed that there is a remarkable similarity among all malignant small round cell tumors, including Ask in tumor and Ewings sarcoma. Overall survival was poor with a 2‐year rate of 38% and a 6‐year rate of 14%. Cancer 1992; 69:1012–1020.

Malignant peripheral neuroectodermal tumours of bone other than Askin's neoplasm: characterization of 14 new cases with immunohistochemistry and electron microscopy.

Peripheral neuroectodermal tumours (PNET) of bone are rare and mimick those seen in soft tissue (peripheral neuroepithelioma of soft tissue). Their differential diagnosis from Ewings sarcoma (Es) is extremely difficult by optical means. Here we report 14 new cases of PNET of bone (other than Askins neoplasm) located primarily in the limbs, pelvic girdle and scapula. Clinically and radiologically they displayed Ewings sarcoma-like features: mean age was 14.4 years, male/ female ratio being 3:11. Metastasis was present in 6 cases at diagnosis (5 with bone metastasis). Prognosis was poor; thirteen patients died; only one with a metatarsal located tumour is alive and free of disease. The mean survival rate was 25 months following diagnosis and treatment with radio- and multimodal chemotherapy. Histologically the 14 cases displayed Homer-Wright rosettes and pseudorosette-like structures, as well as a fibrillary background and lobular pattern. Immunohistochemistry revealed positivity in a number of neural markers when using paraffin-embedded material: NSE, B-2-microglobuline, HNK-1 (leu-7) and E-36 antibodies. At EM level the cell cytoplasms evidenced dense-core granules with neurosecretion, neurotubules and intermediate filaments like those seen in peripheral neuroepithelioma.

Soft tissue Ewing's sarcoma: Characterization in established cultures and xenografts with evidence of a neuroectodermic phenotype

This study characterizes the histogenesis of soft tissue Ewings sarcoma (StEs) based upon an analysis of three tumors. Long‐term cultured cell lines and nude mice xenografts were established from original neoplasms or from their metastases. Histologically they revealed a small round cell pattern without signs of differentiation. Several ultrastructural features of neural type were found; the same were also seen on culture cell lines. Moreover, immunohistochemical study for neural markers revealed the presence of HNK‐1, NSE, LIRC‐LON 36, S‐100 protein, glial fibrillary acidic protein, neurofilaments (70 kilodaltons), and chromogranin; some of these markers were present only in the transplants. Cytokeratin was also seen. the translocation t(11;22)(q24;q12) was found in all three neoplasms together with other chromosomal abnormalities. N‐myc RNA gave negative results whereas c‐myc RNA was expressed. Therefore it may be postulated that StEs displays neuroectodermal features somewhat similar to those seen in peripheral neuroepithelioma as well as in atypical Ewings sarcoma of bone.

Soft tissue Ewing sarcoma--peripheral primitive neuroectodermal tumor with atypical clear cell pattern shows a new type of EWS-FEV fusion transcript.

This study describes a new case of Ewing sarcoma (ES)-peripheral primitive neuroectodermal tumor (pPNET) with unusual phenotype and fusion gene structure. The tumor located in the inguinal area of a 15-year-old boy showed a highly aggressive behavior with hematogenous metastases after intensive chemotherapy and bone marrow transplant, causing death 28 months after diagnosis. The tumor displayed a clear cell pattern, and several neuroectodermal markers proved positive both in the original tumor and in xenografts. This neuroectodermal character was confirmed by electron microscopy. Moreover, cytogenetically the tumor has an unusual chromosomal rearrangement, t(2;22)(q13;q22),t(3;18)(p21;q23), representing a new EWS-FEV fusion type in which exon 7 of EWS gene is fused with exon 2 of FEV gene. This is the third published study of an ES-pPNET showing EWS-FEV fusion described, but it is the first study of a tumor with the aforementioned fusion points. These findings support the genetic and morphologic heterogeneity existing within the group of ES-pPNET tumors.

Molecular Alterations of the Rbi, Tp53, and Mdm2 Genes in Primary and Xenografted Human Osteosarcomas

We report the status of the RBI, TP53, and MDM2 genes in human osteosarcomas and cell lines established from surgical specimens and transplanted into athymic naked mice. By using reverse transcriptase-polymerase chain reaction (RT-PCR) as a prescreening technique and posterior sequencing, we observe new mutations in the RBI gene, notably a duplication in tandem of exons 3 through 6. TP53 mutations appear in codons most frequently mutated in osteosarcomas. We have not seen MDM2 gene amplification in any reported case. These molecular alterations appear in different osteosarcomas not simultaneously present in the same tumor sample. A link has been described between these three genes in the pathways that control the cell cycle and the tumoral progression, but their functions are probably independent in the development of osteosarcomas. TP53 mutations appear in adult patients, whereas RB1 alterations occur mostly in younger patients.

Ultrastructure of vascular neoplasms: A transmission and scanning electron microscopical study based upon 42 cases

Summary The vascular tumors are morphologically recognized by their ability to configurate complete or atypical angiomatous structures. Based on our personal experience of 42 cases of benign and malignant angiomatous tumors, we discussed several aspects of their histogenesis and its morphology when studied with transmission and scanning electron microscopy. Therefore, a survey of the normal histology was developed based not only on normal adult histological structures but also on reparative tissues, as in chronic inflammatory reactions of the gingival mucosa, regenerative tissue of wounds and in chronic osteomyelitis. Supported by morphological arguments, we postulate the existence of several endothelial cell subpopulations, which are involved through several ways in tumoral angiogenesis. This fact is clearly seen in benign capillary angioma, in pseudopyogenic granuloma of the skin and in cellular angioma of infancy. Among the malignant vascular tumors, the hemangiopericytoma shows a large cell heterogeneity, dilating from well developed pericytes to fusocellular and anaplastic ones; well differentiated hemangiopericytoma keeps an epithelial-like appearance and its cells surrounded by basement membranes. It seems possible to distinguish an hemangioendothelioma from an angiosarcoma (hemangiocarcoma). Both are angiogenic neoplasms of malignant nature, but the first is mainly composed by transformed endothelial cells of a mesenchymal nature, similar to those seen in embryonic angiogenesis. The second tumor type possesses not only endothelial cells but also mesenchymal angioblasts from which other cells derivatives are conformed as atypical pericytes. Furthermore, in some cases angiosarcoma displays embryonic metaplastic hematopoiesis (erythropoiesis) inside the neoformed stroma. Histogeneis of Kaposi sarcoma of the skin remains a matter of controversy. The histiocytic endothelial cells could be considered as the primitive endothelial cell subpopulation from which this tumor group could be originated. Bone vascular tumors adopt a more specific texture. Particular emphasis is given to the angiogenic variant of Ewings sarcoma, from which three cases have been isolated among the 219 neoplasms reviewed.

Value of nude mice xenografts in the expression of cell heterogeneity of human sarcomas of bone and soft tissue.

Nude mice xenotransplants have been performed on human primary sarcomas of bone and soft tissues in order to delve into the cell heterogeneity of these neoplasms. Particular emphasis has been given to the group of small round blue cell sarcomas (Ewings sarcomas and peripheral neuroectodermal tumors). Out of 31 xenotransplanted sarcomas, 16 cases have grown positively, and many of them continue to be transferred into nude mice on a regular time basis, being presently considered as fully established nude lines. Here we report the results of such a system, which has been followed with optical, electron microscopical, immunohistochemical and cytogenetic techniques. Osteosarcomas make up the group with the highest number of positivities taken (6 out of 9 transplanted cases). Diversity in growth rate, positive tumors and morphology are taken into consideration. Epithelial foci were seen in one of the transplanted neoplasms. Malignant fibrous histiocytoma and other mesenchymal sarcomas of bone and soft tissues are reviewed. Changes in immunohistochemical reactivity (alpha-1AT and alpha-1AQT) were observed in the transplanted neoplasms. Cytogenetic analysis performed on an undifferentiated (primitive) soft-tissue sarcoma provided clues to its synovial origin. Analysis of Ewings sarcoma performed on nude mice transplanted tumors shows heterogeneous immunohistochemical response, with enhancement of cytokeratin positive cells, not previously seen in the primary neoplasms.

Translocation (X;18) in a biphasic synovial sarcoma with morphologic features of neural differentiation.

The authors report a recurred neoplasm showing distinctive histologic, immunophenotypic, and ultrastructural features characteristic of biphasic synovial sarcoma with neural differentiation. The features include areas with a growth pattern of densely packed spindle cells in irregularly intersecting, broad fascicles, diffuse vimentin and HBA 71 immunoreactivity, expression of S-100 protein, and other neural markers. Moreover, areas with glandular structures and cellular expression of cytokeratin and epithelial membrane antigen were noted. Additionally, areas of neural-like growth pattern were positive for neuron-specific enolase, HNK-1, and protein gene product 9.5. Furthermore, cytogenetic analysis, two-color interphase fluorescence in situ hybridization, and reverse transcription polymerase chain reaction demonstrated the reciprocal translocation between chromosomes X and 18 associated with the different subtypes of tumor cells. The establishment and characterization of the tumor cell line are detailed. This cell line retains the distinct morphologic and genetic characteristics of the original biphasic synovial sarcoma with neural differentiation.