A rare case report of renal ewing sarcoma/primitive neuroectodermal tumor with ACTH production.

BACKGROUND: Ewing sarcoma/primitive neuroectodermal tumor (PNET) of the renal is extremely rare. The common cause of ectopic ACTH syndrome is pulmonary neuroendocrine tumors, such as small cell carcinomas and carcinoid tumors. Here, we present an unusual case of ectopic ACTH syndrome and hypothyroidism caused by Ewing sarcoma/PNET of the right kidney. CASE PRESENTATION: A 19-year-old girl presented with a history of right lumbar pain and discomfort for 2 months, aggravated for 2 days. Abdominal contrast-enhanced computed tomography and computed tomography angiography showed an upper pole occupancy of the right kidney occupancy with subepithelial hemorrhage. Preoperative hormone levels including plasma total cortisol (PTC), adrenocorticotrophic hormone (ACTH) and thyroid hormone measurements were abnormal, indicating that the patient had Cushing syndrome and hypothyroidism. The patient underwent right radical nephrectomy. Histopathological analysis revealed a renal small round blue cell tumor (consistent with a primitive neuroectodermal tumor), with positive immunohistochemistry for CD99 and Ki67 (about 10%) and molecular pathology for EWSR1 gene fusions. PTC, ACTH and thyroid hormone returned to normal after surgery. CONCLUSIONS: We report a rare ectopic ACTH syndrome and hypothyroidism due to renal Ewing sarcoma/PNET. The clinical manifestation of renal Ewing sarcoma/PNET is non-specific and the diagnosis relies on pathological morphology, immunohistochemistry and fusion gene detection. At present, surgery combined with radiotherapy and chemotherapy is used in the treatment, but the prognosis is still not optimistic.

Ovarian Primitive Neuroectodermal Tumor: Are You Central or Peripheral?

Primitive neuroectodermal tumors (PNETs) of the ovary are rare, highly aggressive neoplasms with fewer than 100 cases described. PNETs of the ovary can be classified as either peripheral or central types. The peripheral PNETs have small round cells with or without rosette formation, and the central PNETs can be further delineated based on the CNS tumor they morphologically resemble. We present a case of a central type ovarian PNET in a young female presenting with a pelvic mass and elevated serum tumor markers.

Features of a rare peripheral primitive neuroectodermal tumour arising from the thoracic spine in a juvenile canine patient.

Peripheral primitive neuroectodermal tumours are rare tumours in juveniles. The current patient was a paraplegic 8-month-old Scottish deerhound with a suspected pulmonary mass. Radiographically, there was a large extrapleural mass within the mid-left hemithorax. On MRI, the mass was mainly hyperintense on T2-weighted images, isointense on T1-weighted images and was heterogeneously strongly contrast enhancing with a multilobulated appearance, spinal cord compression, paraspinal musculature invasion and intrathoracic extension. Those changes were confirmed on post-mortem, and the mass diagnosed based on immunohistochemistry.

Primary vulvar Ewing sarcoma/peripheral primitive neuroectodermal tumor with pelvic lymph nodes metastasis: A case report and review of literature.

Ewing sarcoma (ES) and peripheral primitive neuroectodermal tumors (pPNET) are soft tissue tumors that generally affect the bones. Extraosseous ES/pPNET has been rarely reported. Our patient presented with a 6 × 4 cm right subcutaneous solid vulvar lesion causing pain and discomfort. Pathology and immunohistochemistry staining showed strong positivity for CD99 and vimentin, favoring the diagnosis of ES/pPNET. Magnetic resonance imaging showed a 6-cm lesion in the right vulvar region with enlarged bilateral inguinal and right iliac lymph nodes. Fluorescence in situ hybridization test for translocation t(11;22)(q24;q12) was positive, confirming the diagnosis. The patient received three cycles of neoadjuvant chemotherapy with vincristine, adriamycin, cyclophosphamide alternating with ifosfamide and etoposide with complete response. The patient underwent vulvar radical local excision. Residual tumor measured 1.6 cm with free margins. She received four additional cycles of adjuvant chemotherapy and 30 sessions radiotherapy. She is currently disease free after 37 months. No ES/pPNET cases with pelvic lymph nodes metastasis were ever reported.

Retroperitoneal extraosseous peripheral primitive neuroectodermal tumor in a Formosan serow: case report and literature review.

A 10-y-old female captive Formosan serow (Capricornis swinhoei) was inactive and was azotemic. An autopsy was performed following her death, and multiple irregularly shaped, white-to-gray masses of 0.5-2 cm diameter were noted on both ureters, the left adrenal gland, urinary bladder, and uterus. Microscopically, organs were effaced by a poorly demarcated, highly infiltrative neoplasm, composed of neoplastic round cells arranged in islands, sheets, or nests with occasional rosette formation. The neoplastic cells were small: ≤2 red blood cell (≤ 15 µm) diameter. The neoplastic cells were positive for CD56, CK, FLI-1, and NSE, but negative for desmin, GFAP, melan A, NF, PAX-8, S100, synaptophysin, and vimentin. Therefore, the diagnosis of retroperitoneal extraosseous peripheral primitive neuroectodermal tumor (pPNET) was made. pPNET with FLI-1 expression has not been reported previously in animals, to our knowledge.

Ewing sarcoma/primitive neuro-ectodermal tumor of the urogenital system in children: a retrospective observational case series.

INTRODUCTION: Pediatric Ewing sarcoma (ES)/primitive neuro-ectodermal tumor (PNET) occurring in the genitourinary system has been rarely reported. And the result of long-term follow-up is still a matter of debate. OBJECTIVE: The aim of the study was to identify the characteristics, therapeutic strategies, and long-term outcomes of pediatric ES/PNET in the genitourinary system. PATIENTS AND METHODS: All children with genitourinary system PNET from a single center were retrospectively reviewed. The American Joint Committee on Cancer (AJCC) staging system was used to evaluate tumor grade. RESULTS: Four patients were included. Three were boys, and 1 was a girl. The locations of the lesions were the penis in 1 patient, ureter in 1 patient, and kidney in 2 patients. Two patients were of AJCC stage IVB, and the other 2 patients were of stage IIA. In the follow-up ranging from 2.5 to 8.0 years, 3 patients had survival, and 1 patient died. The patient with penis PNET survived during the 8 years of follow-up. One patient with renal PNET had tumor thromboses in the renal vein, inferior vena cava, and right atrium, which was the first definite report in children (case 3). DISCUSSION: Primitive neuro-ectodermal tumor as a highly malignant subgroup of blue round cell tumor is extremely rare in the genitourinary system, especially in children. The current case series represents the first report of penis PNET in children with the longest (8 years) follow-up and first definite report of pediatric renal PNET with vena cava and atrium tumor thrombus. In contrast to the previous literature, the patient with ureteral PNET in this study was much younger, who was the youngest child to be reported in the literature thus far. Although the key prognostic factor of the outcomes is detectable metastases at diagnosis, the patient with penis PNET and bone and lung metastasis in this series still survived. It was hypothesized from the data of present cases that young age was a protective factor, which was consistent with the previous literature. Aggressive therapy is not trivial for patients with multiple recurrences who can also be a long-term survivor. The survival outcomes of these high-stage patients were favorable with combination treatment. As the patient with penis PNET in this series had bone metastasis at his 7.5 years after definite diagnosis, five years of follow-up was not enough. The follow-up period should be extended, even to a lifetime follow-up. CONCLUSIONS: Children with PNET have a better prognosis than adults. Aggressive combination treatment should be performed to improve prognosis and the survival rate. It is better to monitor the changes of the disease by extending the follow-up period.

Ewing's Sarcoma/Peripheral Primitive Neuroectodermal Tumors in Bronchus.

Ewing sarcoma/peripheral primitive neuroectodermal tumors (ES/pPNET), a member of the Ewing sarcoma family of tumors, is a malignant soft tissue tumor with small undifferentiated neuroectodermal cells. Primary trachea-bronchial ES/pPNET is very rare. The most common pulmonary ES is due to a metastasis. We describe a case of ES/pPNET which originated in the left basal trunk bronchus. The patient was a 30-year-old male, presenting with irritable cough and fever for 10 days. A tumor of 60 mm in diameter was found in the left basal trunk bronchus, extending to the left lower lobe. No distant metastases were detected. Histopathological examination revealed a malignancy of ES/pPNET with a diffuse proliferation of round cells, a Flexner-Wintersteiner rosette formation and positive staining for CD99. The patient was successfully treated with a combination of left lower lobectomy and adjuvant chemotherapy and has remained disease-free for approximately 18 months at follow-up. This case highlights that ES/pPNET should be considered as a differential diagnosis in cases of trachea-bronchial tumors.

Tumor neuroectodérmico primitivo / Primitive neuroectodermal tumor

El tumor neuroectodérmico primitivo periférico (PPNET) o neuroepitelioma periférico es una neoplasia maligna de células redondas azules pequeñas derivadas de la cresta neural. Es uno de los tipos histológicos más indiferenciados entre los tumores malignos. Por ser indistinguible del sarcoma de Ewing, desde el punto de vista de imagen e histología, se considera una única patología para su estudio. Puede aparecer en la infancia o más frecuente en la adolescencia; el tratamiento incluye quimioterapia, cirugía y radioterapia. Se presenta el caso clínico de un paciente de 77 años de edad que consulta por ptosis palpebral y es catalogado como Síndrome de Horner. El diagnóstico final fue tumor neuroectodérmico periférico confirmado con histopatología e inmunohistoquímica

A primitive neuroectodermal tumor (PPNET) or peripheral neuroepithelioma is a malignant neoplasm of small round blue cells derived from the neural crest. It is one of the most undifferentiated histological types among malignant tumors, because it is indistinguishable from Ewing's sarcoma from the imaging and histology perspective. It considers a single pathology for this paper. It can appear in childhood or more frequently in adolescence; treatment includes chemotherapy, surgery, and radiation therapy. We present the clinical case of a 77 year-old patient who consulted for palpebral ptosis, and it classifies as Horner's Syndrome. The final diagnosis was a peripheral neuroectodermal tumorconfirmed with histopathology and immunohistochemistry.

Multimodal treatment of pediatric patients with Askin's tumors: our experience.

BACKGROUND: We report our experience and outcomes about the management of Askin's tumors [AT], which are rare primitive neuroectodermal tumors (PNETs) that develop within the soft tissue of the thoracopulmonary region, typically in children and adolescents. METHODS: We retrospectively analyzed the charts of 9 patients affected by AT (aged 6-15 years), treated at the Paediatric Oncology Unit of Gemelli University Hospital in Rome between January 2001 and December 2016. RESULTS: All nine patients underwent to biopsy followed by neoadjuvant chemotherapy. At the end of the neoadjuvant chemotherapy, they underwent to surgical removal of the residual tumor. Five patients with positive tumor margins and/or necrosis< 90% received local radiotherapy. Two patients with metastasis received an intensified treatment, with the addition of high dose adjuvant chemotherapy followed by peripheral blood stem cells rescue. No statistically significant correlation was found between outcome and gender; the presence of any metastasis and the radiotherapy. The overall survival was 65.14 months (95% confidence interval [95%CI], 45.81-84.48), and the 5 years survival was 60%, at a median follow-up of 53.1 months. CONCLUSION: Our study confirms that a multimodal treatment with surgery, chemotherapy, and radiotherapy may increase the survival in AT pediatric patients.

Primitive Neuroectodermal Tumors of the Female Genital Tract: A Morphologic, Immunohistochemical, and Molecular Study of 19 Cases.

Primary primitive neuroectodermal tumor (PNET) of the female genital tract is rare, and its proper classification remains unclear. The clinical, histologic, and immunophenotypic features as well as EWSR1 rearrangement status of 19 gynecologic PNETs, including 10 ovarian, 8 uterine, and 1 vulvar tumors, are herein reported. Patient age ranged from 12 to 68 years, with a median age of 20 and 51 years among those with ovarian and uterine PNETs, respectively. Morphologic features of central nervous system (CNS) tumors were seen in 15 PNETs, including 9 medulloblastomas, 3 ependymomas, 2 medulloepitheliomas, and 1 glioblastoma, consistent with central PNET. The remaining 4 PNETs were composed entirely of undifferentiated small round blue cells and were classified as Ewing sarcoma/peripheral PNET. Eight PNETs were associated with another tumor type, including 5 ovarian mature cystic teratomas, 2 endometrial low-grade endometrioid carcinomas, and a uterine carcinosarcoma. By immunohistochemistry, 17 PNETs expressed at least 1 marker of neuronal differentiation, including synaptophysin, NSE, CD56, S100, and chromogranin in 10, 8, 14, 8, and 1 tumors, respectively. GFAP was positive in 4 PNETs, all of which were of central type. Membranous CD99 and nuclear Fli-1 staining was seen in 10 and 16 tumors, respectively, and concurrent expression of both markers was seen in both central and Ewing sarcoma/peripheral PNETs. All tumors expressed vimentin, whereas keratin cocktail (CAM5.2, AE1/AE3) staining was only focally present in 4 PNETs. Fluorescence in situ hybridization was successful in all cases and confirmed EWSR1 rearrangement in 2 of 4 tumors demonstrating morphologic features of Ewing sarcoma/peripheral PNET and concurrent CD99 and Fli-1 expression. In conclusion, central and Ewing sarcoma/peripheral PNETs may be encountered in the female genital tract with central PNETs being more common. Central PNETs show a spectrum of morphologic features that overlaps with CNS tumors but lack EWSR1 rearrangements. GFAP expression supports a morphologic impression of central PNET and is absent in Ewing sarcoma/peripheral PNET. Ewing sarcoma/peripheral PNETs lack morphologic features of CNS tumors.

Primitive neuroectodermal tumour of the cervix: a rare diagnosis.

A 48-year-old woman presented with symptoms of lower abdominal pain and vaginal discharge for 6 months. Clinical examination and pelvic ultrasound scan suggested a diagnosis of infected Gartner's cyst, for which she underwent vaginal cystectomy. However, histopathology and immunohistochemistry revealed a diagnosis of primitive neuroectodermal tumour of the cervix. Further investigations revealed the stage to be FIGO IIIB, which was inoperable. She received neoadjuvant chemotherapy (vincristine, adriamycin, cyclophosphamide alternating with ifosfamide, cisplatin and etoposide, every 21 days), but the tumour did not respond to treatment and she was started on radiotherapy with definitive intent (55.8 Gray in 31 fractions over 6.2 weeks). A PET-CT performed 2 months after completion of radiotherapy showed complete response, and she is now receiving adjuvant chemotherapy.

Comparative retrospective study on the modalities of biopsying peripheral neuroblastic tumors: a report from the Italian Pediatric Surgical Oncology Group (GICOP).

BACKGROUND: Peripheral neuroblastic tumors are the most common extracranial solid neoplasms in children. Early and adequate tissue sampling may speed up the diagnostic process and ensure a prompt start of optimal treatment whenever needed. Different biopsy techniques have been described. The purpose of this multi-center study is to evaluate the accuracy and safety of the various examined techniques and to determine whether a preferential procedure exists. METHODS: All children who underwent a biopsy, from January 2010 to December 2014, as a result of being diagnosed with a peripheral neuroblastic tumor, were retrospectively reviewed. Data collected included patients' demographics, clinical presentation, intraoperative technical details, postoperative parameters, complications, and histology reports. The Mann-Whitney U and Fisher's exact tests were used for statistical analysis. RESULTS: The cohort included 100 patients, 32 of whom underwent an incisional biopsy (performed through open or minimally invasive access) (Group A), and the remaining 68 underwent multiple needle-core biopsies (either imaging-guided or laparoscopy/thoracoscopy-assisted) (Group B). Comparing the two groups revealed that Group A patients had a higher rate of complications, a greater need for postoperative analgesia, and required red blood cell transfusion more often. Overall adequacy rate was 94%, without significant differences between the two groups (100% vs. 91.2% for Group A and Group B, respectively, P = 0.0933). CONCLUSIONS: Both incision and needle-core biopsying methods provided sub-optimal to optimal sampling adequacy rates in children affected by peripheral neuroblastic tumors. However, the former method was associated with a higher risk of both intraoperative and postoperative complications compared with the latter.

Meningeal Ewing Sarcoma/Peripheral PNET: Clinicopathological, Immunohistochemical and FISH study of four cases.

Meningeal Ewing Sarcoma (ES)/peripheral primitive neuroectodermal tumor (pPNET) is a rare diagnostically challenging small round cell tumor in the CNS. This study investigates the clinical pathological features of four cases of this tumor from archives of 6 years in our hospital. Patients were within the median age of 21.5 years and male to female ratio was 1:1. The tumors distributed at the supra-tentorial location, posterior fossa and lumbar vertebral canal, usually presenting as the dura-sited nodule or having close connection with the meninges within the cranium or vertebral canal. Histopathologically, small round undifferentiated tumor cells with hypercellularities, scant cytoplasm and inconspicuous nucleoli were observed, although some components such as atypical larger vesicular nuclei, prominent nucleoli of tumor cells, necrotic foci and mesenchymal collagen proliferation forming the lobular structure, were also appreciated. Immunohistochemally, tumor cells displayed membranous positivity of CD99 (4/4), nuclear positivity of FLI-1 (4/4) and NKX2.2 (4/4), negativity of EMA, GFAP and synaptophysin expression. The histochemical PAS staining showed weak positivity in one case. Fluorescence in situ hybridization (FISH) test using EWSR1 (22q12) dual color break apart rearrangement probe showed positive results in two cases. Results suggest that using a panel of immunohistochemical markers, including NKX2.2, CD99, FLI-1, EMA, GFAP and synaptophysin, combined with the supplementary EWSR1 FISH test, helps to define the diagnosis of meningeal ES/pPNET of CNS.

Immunohistochemical detection of FLI-1 protein expression in Ewing Sarcoma/ peripheral primitive neuroectodermal tumour: A study of 50 cases.

OBJECTIVE: To determine friend leukaemia integration 1 transcription factor protein expression in cases of Ewing sarcoma. METHODS: This retrospective, descriptive study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, and comprised data of diagnosed cases of Ewing sarcoma related to the period from February 2013 to December 2014. Clinico-pathological features, including patient age, gender and site of biopsy were studied. Positivity of immunohistochemical markers such as cluster of differentiation 99(membranous staining) and Friend leukaemia integration 1 transcription factor (nuclear staining) were noted. SPSS17 was used for data analysis. RESULTS: Of the 50 Ewing sarcoma cases, 26(52%) related to women and 24(48%) to men. The overall mean age was 17+11.53 years (range: 3 to 42 years). Moreover, 30(60%) patients had presented with bone swelling or growth whereas 20(40%) had presented with soft tissue swelling. The site of presentation was upper extremities in 16(32%) patients, lower extremities in 14(28%), maxilla in 7(14%), chest wall in 6(12%), paraspinal region in 4(8%), scalp in 2(4%) and retroperitoneum in 1(2%). Membranous positivity for cluster of differentiation 99 was seen in 48(98%) cases. Nuclear positivity for Friend leukaemia integration 1 transcription factor was seen in 39(78%) cases. CONCLUSIONS: Friend leukaemia integration 1 transcription factor was found to be a useful marker in diagnosing Ewing sarcoma/peripheral primitive neuroectodermal tumour. However, its positivity was more dependable when it was used in combination with other markers such as cluster of differentiation 99.

[CT and MRI manifestations of the axial area primary peripheral primitive neuroectodermal tumors].

OBJECTIVE: To explore CT and MRI manifestations of the axial area peripheral primitive neuroectodermal tumors (pPNETs) in order to improve the knowledge of this disease. METHODS: The clinical data of 10 patients with pPNETs underwent pathologically confirmed were retrospectively analyzed from October 2008 to May 2014. There were 7 males and 3 females, aged from 8 to 49 years old with median of 23.6 years. The preoperative multi-slice spiral CT scan was completed in 3 cases, plain CT scan and enhancement in 4 cases; MRI and enhancement scanning in 5 cases; and among them, 2 cases underwent both MRI and CT scan. RESULTS: In-bone type was found 6 cases and out-bone type was found 4 cases. Three cases occurred in sacral vertebrae, 2 cases in lumbar vertebrae, 1 case in cervical vertebrae, 1 case in cervical spinal canal, 1 case in coccyx, 1 case in the right iliac bone, 1 case in presacral space. Cross sectional the smallest tumor maximum level was 1.1 cmx 1.2 cm in size, the biggest tumor was 8.0 cm x 9.2 cm, the median size was 4.4 cm x 5.7 cm, of them, the tumor of maximal diameter larger than 5 cm had 6 cases. Except 2 cases-without destruction of bone, the other 5 cases with osteolytic destruction, 2 cases with calcification, 1 case with mixed. Equidensite was main in CT scan, 1 case with uniform density, other 6 cases with uneven density,in which 3 cases with "floating ice" change; 1 case with moderate strengthening, other 3 cases with obviously strengthening, 2 cases with multiple small blood vessels in enhancement scanning. MRI of 5 cases showed the signal of isointensity on T1WI, the slightly high signal on T2WI and the signal was not uniform; after enhancement scan, the signal of 5 cases obviously enhanced. Two patients complicated with vertebral compression fractures, no periosteal reaction was found in all patients, and no the destruction of intervertebral disk was found in 5 patients of MRI scan. CONCLUSION: The axial area pPNETs is common among children and the youth, and the mass often is huge. The mass of in-bone type often envelopes the vertebral body, and main located on prevertebral space, all associated with bone destruction, osteolytic destruction is common, and primary vertebral bodies also is common, attachment primary or involvement is few found, it can involve the spinal canal and anterior wall of spinal canal is common, some cases complicate with multiple newly born small vessels. The mass of out-hone type in deep soft tissue is common, minority primary spinal canal, many complicated with vertebral bone destruction, osteolytic destruction was main. The intervertebral disk was not invaded and intervertebral space has not stenosis. CT scan offer complicate with "floating ice" sign, and in-bone type is common. Isointensity is main on MRI TlWI and slightly longer signal is main on MRI T2WI, strengthening signal is obvious.

Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Kidney: A Rare and Lethal Entity.

Ewing sarcoma/primitive neuroectodermal tumor represents a spectrum of undifferentiated tumors with similar biology that together represent the second most common sarcoma in the pediatric-young adult age range. Very rarely, this tumor presents as a primary neoplasm of the kidney. The clinical presentation of this tumor is not specific, and other renal tumors may present with a similar histologic appearance. Establishing the correct diagnosis is critical because renal Ewing sarcoma/primitive neuroectodermal tumor carries a strikingly dismal prognosis and thus dictates a specific treatment strategy. A low threshold for the use of ancillary molecular tests is recommended, particularly in diagnostically problematic cases. Important considerations with regards to morphology, immunohistochemistry, and molecular alterations will be reviewed here and should be taken into account before rendering this rare and lethal diagnosis.

Multiple Ewing Sarcoma/Primitive Neuroectodermal Tumors in the Mediastinum: A Case Report and Literature Review.

Ewing sarcoma/primitive neuroectodermal tumors (ES/PNET) are high-grade malignant neoplasms. These malignancies present very rare tumors of thoracopulmonary area and even rarer in the mediastinum. In our knowledge, ES/PNET presented with multiple mediastinal masses has not been reported previously. We experienced a case of a 42-year-old man presented with gradual onset of left-side pleuritic chest pain. A contrast-enhanced chest computed tomography (CT) scan showed separate 2 large heterogeneously enhancing masses in each anterior and middle mediastinum of the left hemithorax. Positron emission tomography-computed tomography (PET-CT) scan revealed high fluorodeoxyglucose (FDG) uptake in the mediastinal masses. After surgical excision for the mediastinal masses, both of the masses were diagnosed as the ES/PNET group of tumors on the histopathologic examination. The patient refused postoperative adjuvant chemotherapy and came back with local tumor recurrence and distant metastasis on 4-month follow-up after surgical resection. We report this uncommon form of ES/PNET. We are to raise awareness that this rare malignancy should be considered as a differential diagnosis of the malignant mediastinal tumors and which can be manifested as multiple masses in a patient. Understanding this rare entity of extra-skeletal ES/PNET and characteristic imaging findings can help radiologists and clinicians to approach proper diagnosis and better management for this highly malignant tumor.

Peripheral Primitive Neuroectodermal Tumor (pPNET) of the Parotid: Report of a Rare Case.

Primitive neuroectodermal tumors (PNETs) are a family of highly malignant soft tissue neoplasms mostly occurring in children and young adults. PNETs usually develop in the thoracopulmonary region, abdomen, pelvis, and rarely in the head and neck region. Here, a case of PNET located in the parotid gland is reported.

Extraosseous Ewing sarcoma in the mesentery: the first report of cases in children.

Extraosseous ewing sarcoma (EES) is a rare soft-tissue tumor usually found in the extremities or paraspinal region. We describe the case of a 4-year-old boy with a large cystic mass in the mesentery diagnosed as mesenteric lymphangioma preoperatively and as EES after partial resection and histopathological examination. EES in the mesentery is extremely rare, with only 2 reports described in the English literature. This represents the first report of EES in a child.