Primitive neuroectodermal tumors of the chest wall

Treatment of children with peripheral primitive neuroectodermal tumor or extraosseous Ewing's tumor with Ewing's-directed therapy

PURPOSE

We report the treatment and outcome of patients with peripheral primitive neuroectodermal tumor (PNET) and extraosseous Ewing's tumor (EOE) using Ewing's-directed therapy, including an ifosfamide and etoposide window.

METHODS

Seventeen pediatric patients with peripheral PNET (n = 14) or EOE (n = 3) were enrolled between 1988 and 1992 on our institutional Ewing's protocol. Induction therapy comprised a 9-week "window" of ifosfamide and etoposide, followed by 9 weeks of therapy with cyclophosphamide and Adriamycin (Adria Laboratories, Columbus, OH). Response assessment after 17 weeks was followed by surgery and/or radiotherapy (doses based on tumor size and response to induction), repeat evaluation, and maintenance chemotherapy with alternating courses of vincristine/dactinomycin, ifosfamide/etoposide, and cyclophosphamide/Adriamycin for a total of 45 weeks.

RESULTS

At diagnosis, 8 patients had large lesions (>8 cm) and 3 had pulmonary metastases (1 with large tumor). Surgical resection was performed at diagnosis for 9 patients and after induction therapy for 5. During window therapy, all of the 9 evaluable patients responded (8 partial, I objective), and no patient without measurable disease developed disease progression. Responses were maintained or improved during subsequent induction in six of the patients with residual disease. Fourteen patients received local radiotherapy. At 49 to 94 months after diagnosis, 12 patients are disease-free (1 in second remission), 4 have died, and 1 is alive with disease. The five-year overall and progression-free survival rates are 77 +/- 13% and 62 +/- 16%, respectively.

CONCLUSION

The use of consistent Ewing's-directed combined-modality therapy for patients with soft tissue peripheral PNET/EOE results in survival similar to that of patients with osseous Ewing's tumor. The combination of ifosfamide and etoposide appears active and should be incorporated in future treatment protocols.

Establishment of a human cell line secreting neuron-specific enolase from a primitive neuroectodermal tumor of the retroperitoneal cavity

Primitive neuroectodermal tumor (PNET) is one of the small round cell malignancies of presumed neural crest origin for which an effective treatment has not yet been established. In the present study, a human cell line, designated KU-9, was established from a 27-year-old male patient with PNET of the retroperitoneal cavity and has been successfully maintained in nude mice and in culture. On histological examination, the primary tumor was composed of poorly differentiated small round cells arranged in clusters showing a variety of mitotic changes, and contained Homer-Wright rosettes. The histopathological appearance of the KU-9 xenografts was similar to that of the primary tumor. Electron microscopy revealed neurosecretory granules and cytoplasmic processes in the xenograft. No significant amplification of N-myc gene was observed in the KU-9 cells. The KU-9 cells showed chromosome numbers ranging from 56 to 61 with consistent structural abnormalities being add(2)(q31), +add(11)(p11.2), +add(13)(p11.1), and +del(22)(q12). Cultured KU-9 cells grew exponentially with a doubling time of about 50 h and a time-dependent increase in medium levels of neuron-specific enolase (NSE) was noted. Serum levels of NSE in KU-9 tumor-bearing nude mice were significantly elevated and a linear relationship between the serum NSE levels and the tumor NSE content or tumor volume was observed, suggesting that serum levels of NSE may reflect the PNET tumor burden and tumor extent. These results indicate that the KU-9 cell line provides a reproducible model system which could be useful in gaining some insight into the histogenesis and oncogenesis of PNET and in establishing an effective treatment for PNET.

Primitive neuroectodermal tumour of the chest wall

The concept of primitive neuroectodermal tumour (PNET) has been evolving for many years, as has its nomenclature. It was first described as a tumour arising in peripheral nerve, when it was called neuroepithelioma. These tumours are part of the differential diagnosis of malignant small round cell tumours, which include Ewing's sarcoma, rhabdomyosarcoma, neuroblastoma and lymphoma, and which appear as sheets of monotonous small round cells on light microscopy, staining dark blue with haematoxylin and eosin. In the 1970's, reports of tumours displaying neural features introduced new terms such as primitive neuroectodermal tumour and peripheral neuroectodermal tumour. A relationship to the undifferentiated primitive neuroectodermal tumours of the central nervous system in children was assumed by the title of these tumours, although it was recognised that they were not necessarily related to peripheral nerves.

Malignant neuroectodermal tumour of the chest wall (Askin tumour): CT and MR findings in eight patients

Malignant neuroectodermal tumour of the chest wall (Askin tumour) is an uncommon malignant neoplasm affecting young adults. We retrospectively reviewed the clinical and pathological information and radiologic studies in our archives on eight cases of this tumour. All cases were pathologically proven. Plain films, CT scans and radionuclide images were available in all cases. MR images were also available in two patients. Although rare, Askin tumour should be included in the differential diagnosis when a chest wall or thoracic paraspinal mass is identified in a young individual.

The radiology of Askin tumours

The Askin tumour is a highly malignant primitive neuroectodermal tumour (PNET) of the chest wall occurring in children and young adults. We describe three cases to illustrate the clinical and radiological aspects of this tumour, which are not well documented. Patients present with a chest wall mass, pain and constitutional symptoms. Radiology demonstrates a large soft tissue chest wall mass, local rib erosion and pleural effusion. Recurrence tends to be local chest wall, pulmonary or skeletal. The prognosis is poor. Askin tumours must be considered in the differential diagnosis of chest wall masses in children and young adults.

Malignant small-cell tumor of the thoracopulmonary region: 'Askin tumor'

Malignant small-cell tumor of the thoracopulmonary region (MSCT) is an uncommon neoplasm in children. We describe five cases diagnosed since 1981 that fulfill the criteria put forth by Askin et al. Surgery was performed for diagnosis or therapy in all patients. Two patients underwent open lung biopsy, only because of tumor extent. The other three had chest wall resections. All patients received radiotherapy and chemotherapy. Three patients presenting initially with extensive disease died at intervals of 2.5 to 7 months after diagnosis. Two patients are alive and disease-free at 16 and 24 months postdiagnosis. All five cases were reviewed for standard histology and differential immunohistochemistry. Electronmicroscopy and tissue cultures were done in 3 of the 5 patients. All five patients were neuron-specific enolase-positive. MSCT is an exclusion diagnosis not always readily made. Clinical course and pathologic expertise may point to the correct diagnosis.

Neuroendocrine carcinoma (Merkel cell tumor?) presenting as a subcutaneous tumor. An ultrastructural and immunohistochemical study of three cases

The clinical and pathological features of three unusual soft tissue tumors are presented. They occurred in the groin of elderly patients in the subcutaneous tissue. In Case 1, the inguino-crural tumor coexisted with a second mass in the pelvis. The tumors had a tendency to recur locally and to invade the regional lymph nodes. Metastatic dissemination of the disease resulted in the death of the patient in Case 3. Histologically, the tumors appeared composed of small round cells with scanty cytoplasms, arranged in diffuse, poorly cohesive or solid sheets. In places, a trabecular pattern was noted. Mitotic figures were numerous. Some cells exhibited argyrophil granules. The ultrastructural study revealed compact whorls of intermediate filaments and neurosecretory granules. All three cases displayed a paranuclear dot-like positive reaction with antibodies to cytokeratins and neurofilaments. A diffuse cytoplasmic immunostaining for neuron-specific enolase was present in Cases 1 and 2. Protein S-100, vimentin and leucocyte common antigen could not be demonstrated. All these characteristics, except for the subcutaneous location, are shared with neuroendocrine (Merkel cell) tumors of the skin.