Peripheral Primitive Neuroectodermal Tumor Research Articles

A CASE OF PRIMITIVE NEUROECTODERMAL TUMOR (PNET) PRESENTING AS ANTERIOR MEDIASTINAL MASS

Peripheral primitive neuroectodermal tumors (pPNET) are a group of highly malignant tumors composed of small round cells of neuroetodermal origin that affect soft tissue and bone ,most commonly present in the thoracopulmonary region (Askin tumor), abdomen , pelvis and rarely in the head and neck. They usually present in the second decade of life, with slight male preponderance and account for 4-17% of all soft tissue tumors. Clinical symptoms depend on the site of presentation but invariably include pain and swelling of surrounding structure due to mass effect. Current recommendations advocate complete surgical resection whenever possible, adjuvant or neoadjuvant chemotherapy and radiotherapy. Here we present a 20 year old male patient who presented with chest pain and breathlessness and on investigation found to have an anterior mediastinal mass which further evaluation found to be a primitive neuroectodermal tumor

Cover Image

Cover caption: The cover image is based on the Case Report Features of a rare peripheral primitive neuroectodermal tumour arising from the thoracic spine in a juvenile canine patient by Adrien-Maxence Hespel et al., https://doi.org/10.1002/vms3.449.

Radiation Therapy (RT) Target Volume Definition for Peripheral Primitive Neuroectodermal Tumor (PPNET) by Use of Multimodality Imaging: An Original Article

Primitive neuroectodermal tumor (PNET) refers to a group of highly malignant tumors consisting of small round...

Resection and reconstruction of a giant primitive neuroectodermal tumour of the abdominal wall with an ultra-long lateral circumflex femoral artery musculocutaneous flap: a case report

BackgroundPrimitive neuroectodermal tumours are clinically rare. Here, we report a case of a large peripheral primitive neuroectodermal tumour of the abdominal wall. The defect was reconstructed with the longest lateral circumflex femoral artery musculocutaneous flap reported to date.Case presentationA 15-year-old male suffered rupture and bleeding of an abdominal wall mass with a volume of approximately 23*18*10 cm3, involving the whole layer of the abdominal wall. Pathological examination revealed a peripheral primitive neuroectodermal tumour. The tumour was removed via oncologic resection, and the abdominal wall was reconstructed with a bilateral 44*8 cm2 lateral circumflex femoral artery musculocutaneous flap combined with a titanium polypropylene patch. The patient had smooth recovery postoperative, and the functions of the donor and recipient areas of the flap were not significantly affected.ConclusionIn this case report, we describe a rare primitive neuroectodermal tumour of the abdominal wall, which invaded almost the entire abdominal wall due to delay of treatment. After thoroughly removing the tumour, we immediately reconstructed the abdominal wall with an ultra-long lateral circumflex femoral artery musculocutaneous flap and achieved better appearance and function after the operation. This case suggests that we should adopt an integrated scheme of surgery combined with radiotherapy and chemotherapy in the treatment of peripheral primitive neuroectodermal tumours. Under the premise of determining the blood supply, the lateral circumflex femoral artery musculocutaneous flap can be cut to a sufficient length.

COMPUTER TOMOGRAPHY AND X-RAY DIAGNOSTICS OF PERIPHERAL PRIMITIVE NEUROEECTODERMAL TUMORS (PNET) IN CHILDREN

Relevance: Peripheral primitive neuroectodermal tumor (PNET) belongs to the group of malignant tumors that develop from migrating embryonic neural crest cells. PNET includes a number of nosological forms: Askin's tumor, esthesioneuroblastoma, the very peripheral primitive neuroectodermal tumor, Ewing's sarcoma . PNET accounts for 3–9% of all soft tissue tumors in children and 19% of all soft tissue sarcomas. In European countries and the United States, the frequency of their occurrence is 3.4 cases per year per 1 million children under 15 years of age, in Kazakhstan - 0.6-1.2 cases per 1 million child population. Rapid tumor growth, malignancy and early metastasis to other organs and systems predetermines its special role in oncology. Objective of the study: to improve the quality and availability of early diagnosis of sarcomas in children in medical institutions of the general medical network. Results of the study: 35 cases of peripheral PNET in children were analyzed. The age of the patients is from 1.5 to 17 years. The average age is 9.3 years. There were 1.3 times more boys among patients than girls. Extra-skeletal localization was found in one patient (3.6%). Radiographically, it is often almost impossible to make a differential diagnosis between the manifestations of Ewing's sarcoma and primary chronic or "healed" (antibiotic) forms of acute hematogenous osteomyelitis in the initial phase of the process, before the formation of the extraosseous soft tissue component. The process of bone damage is more often localized in its diaphysis and subsequently spreads to the metaphyses of the bone.

Unusual Presentation of Peripheral Primitive Neuroectodermal Tumor: A Rare Case Report

A primitive neuroectodermal tumor (PNET) is a rare entity occurring most commonly in the 2nd and 3rd decade and is very rare in patients over 40 years of age. PNET is a round cell malignancy of presumably primitive neuroectodermal tissue or migratory neural crest cells arising from soft tissue or bone. PNET occurring outside the central nervous system is called peripheral PNET (p PNET) and most commonly involves the trunk and extremities Here we present a case of PNET diagnosed in an elderly male who presented with a soft tissue mass in the gluteal region. The histopathology with ancillary techniques including immunohistochemistry and molecular studies helped in establishing the diagnosis of PNET. They are characterized by translocation leading to the fusion of Ewing’s Sarcoma (EWS) gene on 22q12 with any of the member of the ETS (E 26 transformation specific or E -twenty – six) family of transcription factors with the most frequent being t (11;22) (q24;12). Intensive multiagent chemotherapy is the mainstay of treatment as it has great potential for metastatic spread. The prognosis of adults with Ewing’s sarcoma (ES)/PNET is not well known, however, some reports suggested that adults with ES/PNET have a poorer prognosis than children. Cytology is the first line of diagnosis for RCT. However, the type-specific diagnosis or final diagnosis of p PNET is based on histopathology aided with IHC and other ancillary techniques.International Journal of Human and Health Sciences Vol. 05 No. 03 July’21 Page: 358-361

Peripheral Primary Neuroectodermal Tumour of the Ileum: A Case Report and Review of the Literature

Background: Ewing’s Sarcoma (ES)/peripheral Primitive Neuroectodermal Tumor (pPNET) is a rare aggressive malignant small round cell tumour. Most of them arise in bony sites, and they represent the second commonest primary osseous malignancy in adolescence and young adults. The localization of the small bowel is very rare, to our knowledge only 35 cases of ES/pPNET of the small bowel have been reported in the literature. Case Presentation: We report a case of pPNET of the ileum in a 26-year-old female, presented abdominal pain with a transit disorder. The clinical examination was unremarkable. The histological and immunohistochemical study confirmed the diagnosis of peripheral primary neuroectodermal tumours. The patient was treated by tumor resection followed by adjuvant chemotherapy. The evolution was good, without recurrence with a follow-up of 12 months. Conclusion: PNET of the ileum is very rare. We report this case to enrich the database of this rare clinical entity and to improve the management of patients with PNET of the ileum.

Radiation diagnosis of peripheral
 primitive neuroectodermal tumors
 (PNET) in children under
 the conditions of the scientific center of
 pediatrics and pediatric surgery
 (Almaty, Kazakhstan)

Relevance: Peripheral primitive neuroectodermal tumor (PNET) belongs to the group of malignant tumors that
 develop from migrating embryonic neural crest cells. PNET
 includes several nosological forms: Askin’s tumor, esthesioneuroblastoma, the very peripheral primitive neuroectodermal tumor, and Ewing’s sarcoma [1]. PNET accounts
 for 3–9% of all soft tissue tumors and 19% of all soft tissue
 sarcomas in children [2, 3]. In Europe and the US, PNETs account for 3.4 cases per year per 1 million children below 15
 years; in Kazakhstan – 0.6-1.2 cases per 1 million child population. Rapid tumor growth, malignancy, and early metastasis to other organs and systems predetermine the PNET’s
 specific role in oncology [4].
 The purpose was to improve the quality and availability of early sarcoma diagnostics in children in medical institutions of the general medical network.
 Results: 35 cases of peripheral PNET in children were analyzed. The age of the patients was 1.5 to 17 years, the average age – 9.3 years. Boys were 1.3 times more than girls. One
 patient (3.6%) had extra-skeletal tumor localization. Children with stage IIB prevailed – 46.4% of cases (13 children).
 Radiographical differentiation between Ewing’s sarcoma and primary chronic or “healed” (antibiotic) acute
 hematogenous osteomyelitis in the initial phase of the process is almost impossible before the extraosseous soft tissue
 component is formed. The bone damage process is more
 often localized in the bone diaphysis and subsequently
 spreads to its metaphyses.
 Conclusion: PNET originates most often from the chest
 wall, so it is advisable to start the X-ray examination from
 the chest. In terms of radiation semiotics, PNET is similar to
 Ewing’s sarcoma and Askin’s tumor; therefore, an additional
 immunohistochemical study of the tumor tissue is required.
 An important indirect diagnostic criterion in Ewing’s sarcoma
 is the predominance of the soft tissue component over the
 bone manifestations. Extended CT and MRI studies with contrast enhancement (chest, abdominal cavity, pelvis, and the
 primary lesion area) and skeletal scintigraphy are required to
 clarify the extent of changes, stage the tumor accurately, and
 assess the tumor dynamics after treatment. The above conclusions generally coincide with the available literature data.

Radiation diagnostics of peripheral primitive
 neuroectodermal tumors (PNET)
 in children at the Scientific Center
 of Pediatrics and Pediatric Surgery
 (Almaty, Kazakhstan)

Relevance: Peripheral primitive neuroectodermal tumor (primitive neuroectodermal tumor – PNET) belongs to the group
 of malignant tumors that develop from migrating embryonic neural crest cells. PNET includes several nosological forms: Askin’s
 tumor, esthesioneuroblastoma, the very peripheral primitive neuroectodermal tumor, and Ewing’s sarcoma. PNET accounts for
 3–9% of all soft tissue tumors and 19% of all soft tissue sarcomas in children. In Europe and the US, PNETs account for 3.4 cases
 per year per 1 million children below 15 years; in Kazakhstan – 0.6-1.2 cases per 1 million child population. Rapid tumor growth,
 malignancy, and early metastasis to other organs and systems predetermine the PNET’s specific role in oncology.
 The purpose of the study was to improve the quality and availability of early sarcoma diagnostics in children at medical
 institutions of the general medical network.
 Results: 35 cases of peripheral PNET in children were analyzed. The age of the patients was 1.5 to 17 years, the average age –
 9.3 years. Boys were 1.3 times more than girls. One patient (3.6%) had extra-skeletal tumor localization. Children with stage IIB
 prevailed – 46.4% of cases (13 children).
 Radiographical differentiation between Ewing’s sarcoma and primary chronic or “healed” (antibiotic) acute hematogenous
 osteomyelitis in the initial phase of the process is almost impossible before the extraosseous soft tissue component is formed.
 The bone damage process is more often localized in the bone diaphysis and subsequently spreads to its metaphyses.
 Conclusion: PNET is more likely to come from the chest wall, so it is advisable to start the X-ray examination from the chest.
 In terms of radiation semiotics, PNET is similar to Ewing’s sarcoma and Askin’s tumor; therefore, an additional immunohistochemical study of the tumor tissue is required. An important indirect diagnostic criterion in Ewing’s sarcoma is the predominance of the soft tissue component over the bone manifestations. Extended CT and MRI studies with contrast enhancement
 (chest, abdominal cavity, pelvis, and the primary lesion area) and skeletal scintigraphy are required to clarify the extent of
 changes, stage the tumor accurately, and assess the tumor dynamics after treatment. The above conclusions generally confirm
 the available literature data.

Outcome of multidisciplinary treatment of peripheral primitive neuroectodermal tumor

Peripheral primitive neuroectodermal tumors (PNETs) constitute very rare and aggressive malignancies. To date, there are no standard guidelines for management of peripheral PNETs due to the paucity of cases arising in various body sites. Therapeutic approach is derived from Ewing sarcoma family, which currently remains multimodal. Our study retrospectively analyzed 86 PNET patients from February 1, 1998 to February 1, 2018 at Peking Union Medical College Hospital with an additional 75 patients from review of literature. The clinicopathologic and treatment plans associated with survival was investigated. Surgery, chemotherapy, female sex, small tumor size, no lymph node metastasis, R0 surgical resection, (vincristine + doxorubicin + cyclophosphamide)/(isophosphamide + etoposide) regimen, and more than 10 cycles of chemotherapy were associated with improved overall survival in univariate analysis. Surgery, more than 10 cycles of chemotherapy, and small tumor size were independent prognostic factors for higher overall survival. Our data indicates that multimodal therapy is the mainstay therapeutic approach for peripheral PNET.

Primary intracranial Ewing sarcoma/ peripheral primitive neuroectodermal tumor, an entity of unacquaintance: a series of 8 cases.

The purpose is to highlight the primary intracranial (meningeal-based) occurrence of Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). This report is a collation of clinicopathological features of eight cases of molecularly and clinicoradiologically confirmed primary (non-metastatic) intracranial (non-osseous) meningeal ES/PNET. The age range was 1 to 33 years with a median age of 9 years. Male to female ratio was 0.6:1. All patients were diagnosed on the debulking surgical material (gross total resection, 2 cases; subtotal resection, 6 cases) and showed primitive embryonal histomorphology with diffuse membranous CD99 immunoexpression and EWSR1 gene rearrangement by fluorescence in situ hybridization. Seven of them showed a typical FISH pattern of split signals with break-apart probe, while one showed an unusual signal pattern of loss of green signals. EFT-2001 adjuvant protocol was followed along with focal radiotherapy (RT) in all cases (except case 8, full course of chemotherapy could not be completed). Two cases had local recurrence-one of them died of disease recurrence before the administration of further treatment. This series adds non-osseous intracranial site to the list of uncommon sites of occurrence for ES/PNET and more importantly emphasizes the need to be considered in a differential list of primary intracranial primitive embryonal tumors before embarking as primary central nervous system (CNS) embryonal tumor, NOS.

Peripheral Primitive Neuroectodermal Tumor of Uterus: A Case Report

Primitive neuroectodermal tumors (PNETs) were first described in 1973 as a group of small round cell tumors that appeared to have developed from neuroectodermal cells. There are two types of PNETs—central and peripheral. Rarely they can present with female genital tract primary, most common being ovary followed by uterus. PNETs of the uterus are rare and have been reported in about 65 cases in the English literature. Even rarer are peripheral PNETs. Hence, we report this case as our contribution to the existing pool of data. A 29-year-old parous lady had a history of undergoing TAH with RSO for heavy bleeding per vagina. Histopathology was reported to be low-grade endometrial stromal sarcoma. A month later, she presented to our institute with complaints of cough. On evaluation, she was found to have a solid cystic lesion in the pelvis, multiple lung lesions and omental deposits. In view of the unlikely correlation of the clinical picture with low-grade ESS, we further investigated and arrived at a diagnosis of uterine PNET. Following this, she received 6 cycles of chemotherapy with ifosfamide, cisplatin and etoposide. There was persistent lesion in peritoneal cavity. Second-line chemotherapy was advised, but unfortunately, she died of the disease about a year from her first presentation. In view of extreme rarity of this aggressive disease, very little is known about its management. Hence, this case is being presented for information and pertinent discussion in order to increase awareness and urge for the much needed consensus regarding its management.

Two first-in-human studies of xentuzumab, a humanised insulin-like growth factor (IGF)-neutralising antibody, in patients with advanced solid tumours

BackgroundXentuzumab, an insulin-like growth factor (IGF)-1/IGF-2-neutralising antibody, binds IGF-1 and IGF-2, inhibiting their growth-promoting signalling. Two first-in-human trials assessed the maximum-tolerated/relevant biological dose (MTD/RBD), safety, pharmacokinetics, pharmacodynamics, and activity of xentuzumab in advanced/metastatic solid cancers.MethodsThese phase 1, open-label trials comprised dose-finding (part I; 3 + 3 design) and expansion cohorts (part II; selected tumours; RBD [weekly dosing]). Primary endpoints were MTD/RBD.ResultsStudy 1280.1 involved 61 patients (part I: xentuzumab 10–1800 mg weekly, n = 48; part II: 1000 mg weekly, n = 13); study 1280.2, 64 patients (part I: 10–3600 mg three-weekly, n = 33; part II: 1000 mg weekly, n = 31). One dose-limiting toxicity occurred; the MTD was not reached for either schedule. Adverse events were generally grade 1/2, mostly gastrointestinal. Xentuzumab showed dose-proportional pharmacokinetics. Total plasma IGF-1 increased dose dependently, plateauing at ~1000 mg/week; at ≥450 mg/week, IGF bioactivity was almost undetectable. Two partial responses occurred (poorly differentiated nasopharyngeal carcinoma and peripheral primitive neuroectodermal tumour). Integration of biomarker and response data by Bayesian Logistic Regression Modeling (BLRM) confirmed the RBD.ConclusionsXentuzumab was well tolerated; MTD was not reached. RBD was 1000 mg weekly, confirmed by BLRM. Xentuzumab showed preliminary anti-tumour activity.Clinical trial registrationNCT01403974; NCT01317420.

Primitive Neuroectodermal Tumour of the Maxilla Sinistra Region

Primitive neuroectodermal tumors (PNET) are a group of malignant tumors composed of small round cells of neuroectodermal origin that affect soft tissue and bone. PNET have a rare incidence, occurring usualy in children and adolescents, rarely in adults. In this case report are focus of Peripheral primitive neuroektodermal tumors. Peripheral primitive neuroectodermal tumors (PNETp) are a group of aggressive malignancies that most commonly present in multiple tissues and organs including kidney, adrenal, bladder, liver, small intestine, colon and rectum, with a preferred location within the chest area (thoracopulmonary region), in the limbs and around the spine, but rarely, in the head and neck area. Here we present a case of the maxilla sinistra PNETp in a 17-year-old girl and we discuss the clinical features, histopathological characteristics, diagnosis, and treatment.

Clinicopathological Study of Extra-Axial Small Round Cell Tumors of the Cranium.

The cranium is a host to a variety of neoplasms and includes small round cell tumors (SRCTs) as an important malignant subset. Although SRCTs are histomorphologically similar, they are histogenetically diverse comprising of malignancies of epithelial, hematolymphoid, neuroectodermal, and mesenchymal origin. The study aimed to review the clinical and pathological profile of cranial SRCTs. Study is a retrospective review (clinical, imaging, and histopathology) of cranial (extra-axial) SRCTs diagnosed on histology (period: 3.5 years). Study included 126 cases constituting 1.5% of all intracranial neoplasms and age ranging from 11 months to 82 years (mean: 34.3 years; M:F = 1.46:1). Peripheral primitive neuroectodermal tumors (pPNET-8.2%) was the commonest neoplasm followed by plasmacytoma (14.2%), poorly differentiated carcinomas (13.5%), lymphomas (9.5%), and sarcomas (8.7%). Rare tumors included glioma (undifferentiated) deposits, germ cell tumors, melanoma, neuroendocrine neoplasms, and embryonal tumor. Children constituted one-third of the total with PNETs, embryonal tumors, and round cell sarcomas being the common neoplasms. Elderly patients constituted 14% with plasmacytomas and epithelial neoplasms being common. Three percent of the tumors remained unclassified. Clinical symptomology was location dependent, headache being the commonest followed by visual symptoms. Radiopathological discordance was high (60%). SRCTs are unusual tumors with a wide spectrum of histogenesis, biology and clinical presentation. Their rarity in cranium, atypical localization, overlapping clinical, and imaging features pose significant difficulty for clinicians, radiologists, and pathologists. A combined algorithmic analysis of the clinical, radiological, and histolopathological findings, supplemented with immunohistochemistry can aid in specific diagnosis which is crucial for optimal management.

Primitive Neuroectodermal Tumors of the Vulva in a Pregnant Woman: Case Report and Review of the Literature

Ewing’s sarcoma and peripheral primitive neuroectodermal tumour (pPNET) are now regarded as two morphological ends of a spectrum of neoplasms, characterised by a t(11;22) or other related chromosomal translocation involving the EWS gene on chromosome 22 and referred to as Ewing family of tumours (EFTs). They usually originate in bone or soft tissue but rarely arise in the vulva. Extra-skeletal Ewing sarcoma in pregnancy is rare. The current case report presents a case of PNET originating in the vulva in a 35-year-old pregnant woman. The patient benefited from a large excision of the tumor after giving birth to a healthy baby girl. She was treated for her pulmonary metastasis with conventional chemotherapy. She has had a stable disease with 6 months’ review. From this, physicians should give more attention to any vulva mass, especially in case of pregnancy that may accelerate the growth of Ewing’s sarcoma of the vulva, which can improve the prognosis of these pregnant women and their pregnancy.

Peripheral primitive neuroectodermal tumors: A retrospective analysis of 89 cases and literature review.

Peripheral primitive neuroectodermal tumors (pPNETs) are rare, small cell carcinomas with a poor prognosis. The aim of the present study was to describe therapeutic approaches, outcomes and probable prognostic factors. The clinical features, treatments, and outcomes of 89 consecutive patients with pPNET treated at the Peking Union Medical College Hospital from 1999 to 2018 were retrospectively reviewed. A total of 43 males and 46 females were included in the study, with a median age of 25 years (range, 5-73 years). The predominantly affected regions were the abdomen and pelvis, followed by the thoracopulmonary region. The mean primary tumor size was 12.6 cm (range, 1-30 cm). A total of 16 patients (18%) initially presented with metastasis. A total of 46 patients received combined therapy, 35 received mono-therapy, and 8 underwent only biopsy with no further treatment. The period of observation ranged from 1-232 months. The median overall survival (OS) time was 15 months [95% confidence interval (CI), 9-21 months], with 3- and 5-year OS rates of 32 and 25%, respectively. Large tumor size [adjusted hazard ratio (aHR)=3.65; 95% CI, 2.07-6.42; P<0.001), metastasis at initial presentation (aHR=4.34, 95% CI, 2.23-8.42; P<0.001), and combined modality treatment (aHR=0.16, 95% CI, 0.06-0.39; P<0.001) were significantly associated with OS. The prognosis of pPNET is, overall, poor. Large tumor size and metastasis at initial presentation are associated with poorer outcomes. This highly malignant tumor requires an aggressive combination of radical resection, chemotherapy and radiotherapy, when indicated.

Cranial Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumors: A Retrospective Study Focused on Prognostic Factors and Long-Term Outcomes.

Purpose: Cranial Ewing sarcoma (ES)/peripheral primitive neuroectodermal tumors (pPNETs) are rarely reported because of their extremely low incidence, and the current understanding of these tumors is poor. The purpose of this study was to illustrate the clinical, radiological, and pathological features of cranial ES/pPNETs and to discuss prognostic factors by survival analysis.Methods: A total of 31 patients who were pathologically diagnosed with cranial ES/pPNETs between 2000 and 2019 were enrolled in this study. To identify which parameters were associated with higher progression-free survival (PFS) and overall survival (OS) rates, univariate and multivariate analyses were performed.Results: The mean follow-up period was 24.8 months (range, 1–109 months). Eighteen (58.1%) patients had local recurrence and seven (22.6%) patients had distant metastasis. The results of the univariate analysis suggest that the extent of resection and adjuvant radiotherapy are potential prognostic factors for PFS and OS. Adjuvant chemotherapy was associated with OS (P = 0.027) but not with PFS (P = 0.053). The multivariate analysis revealed that the extent of resection and adjuvant radiotherapy were independent prognostic factors for both PFS and OS. In addition, metastasis was an adverse prognostic factor for OS.Conclusions: Surgical management plays a crucial role in the treatment of cranial ES/pPNETs, and gross total resection should be striven for whenever possible. Post-operative radiotherapy is highly recommended to improve PFS and OS. This study also confirms that metastasis is an adverse prognostic factor for cranial ES/pPNETs.

Case report of primitive neuroectodermal tumor with an unknown primary presenting with multiple lung metastasis

Ewing sarcoma or peripheral primitive neuroectodermal tumor (ES or pPNET) is a very aggressive cancer affecting children and young adults, with a five-year survival of 70–80% for localized disease and 30% for metastatic disease. ES can originate in any bone, but is most commonly reported in the lower extremities. To date, no cases of metastatic ES have been reported with an unknown primary in a patient over 45 years of age. We herein report the first documented case of metastatic ES to the lung with an unknown primary. Early diagnosis of rapidly invasive cancers such as ES is critical for effective treatment, which requires a multiple course combined chemotherapy regimen. The present case reports an atypical presentation of metastatic ES with bilateral involvement of the lungs and an unknown primary. We were able to definitively diagnose our patient with ES instead of other similar diseases such as small blue round cell tumor through immunohistochemical markers CD99 and NKX2.2, and began appropriate treatment.

EP1.17-12 Multimodal Aggressive Managment for Askin' Tumor: Results and Prognosis About 3 Cases

Peripheral primitive neuroectodermal tumor (pPNET) is a highly aggressive small round cell tumor belonging to PNET/Ewing sarcoma family. Askin”s tumor is a rare entity of neuroectodermal pathology that starts from the soft parts of the chest wall. It is observed with predilection in the young subject. Herein ; We discuss follow up of three cases after multimodal therapy. We report the case of three patients aged respectively 18; 20; 60 years; whose main symptom in consultation is the appearance of a thoracic parietal mass gradually increasing in size and painful. The general condition was completely preserved in all three patients; and the clinical examination is without abnormalities apart from clubbing in the person aged on a past of smoking. Imaging revealed the presence of a thoracic parietal tumor, the largest of which was 15 X 10X 6 cm without signs of locoregional or distant extension with weak contrast. The histological diagnosis was made on a transparietal mass biopsy with a conclusive immuohistochemical study in favor of a PNET tumor (Askin'tumor) Management was multimodal with 6 aggressive chemotherapy cycles, followed by extensive carcinologic resection surgery and radiation therapy on the tumor bed. We deplore the loss of a patient after distant recurrence in 8th month ; the other two patients remain alive after 25 and 36 months of progression without recurrence. Askin”s tumor is a bone or extra-bone tumor that is histologically similar to Ewing”s sarcoma and PNET, which is characterized by its thoracic location. These three tumors appear to represent different forms of the same entity. They present the same specific chromosomal translocation (11q24-22q12) and, in immunohistochemistry, the same expression of the MIC2 oncogene (CD99) and of the translocation-related FLI-1 protein. The diagnosis is often made at the late stage of locoregional or remote invasion. The treatment is mainly based on surgery and radiotherapy and postoperative chemotherapy to reduce recurrence. The prognosis is unfavorable with a survival at 2 years not exceeding 40% after treatment. Pulmonary metastases are frequently observed even a few years after surgery.