Objective: To investigate the clinicopathological and molecular characteristics of primary renal Ewing sarcoma. Methods: Seventeen cases of primary renal Ewing sarcoma were collected, diagnosed from January 2011 to May 2023 at Peking University Third Hospital (11 cases), Peking University Institute of Urology (4 cases), and Peking University Cancer Hospital (2 cases). The clinical, histopathological, and molecular features were studied using HE staining, immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and targeted next-generation sequencing (NGS). The prognostic correlations were assessed. Results: The cohort included 9 males and 8 females, aged 32 (24, 46) years. Presenting symptoms included hematuria and lumbar pain (13/17), right lower limb/buttock edema (1/17) and persistent low fever (1/17), and other two cases were incidentally detected by imaging in physical examination. All tumors showed renal venous/inferior vena cava tumor thrombosis and were treated with radical nephrectomy and thrombectomy. The tumor maximum diameters were 13.0 (9.0, 15.5) cm. Histologically, tumors showed morphology of diffuse sheets of small round cells with indistinct borders, round nuclei, fine chromatin, and frequent mitoses. Focal rosette-like structures were identified. The morphological heterogeneity was noted in 11 cases, including short spindle-shaped cells, gland-like structure formations, and hemangioma-like patterns. Renal pelvis invasion (5/17) and perirenal fat involvement (10/17) were identified. Immunohistochemistry showed diffuse positive for CD99 (17/17) and NKX2.2 (12/12), while FLI1 was positive in 6/12. Ki-67 indices ranged from 5% to 85%. FISH results confirmed EWSR1 rearrangement in all cases, and NGS (6/17) validated EWSR1-FLI1 fusions. Follow-up (3-84 months; 13/17) revealed metastases in 6 patients (adrenal gland, liver, bone, lung and peritoneum; 3-36 months post-surgery), of which 2 patients died, 1 patient with unknown time of death. The other 6 patients remained disease-free. All the metastatic cases showed elevated Ki-67 index (50%-70%) and necrosis. Conclusions: Primary renal Ewing sarcoma is an aggressive malignant tumor, often diagnosed at advanced stages with venous tumor thrombosis. The morphological heterogeneity and high rate of hemorrhage and necrosis are correlated with more invasive potential, suggesting prognostic significance.

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive malignancy predominantly affecting young male patients, typically originating from the abdomen or pelvis, with a poor prognosis. Since the first description as a distinct clinical entity in 1989, approximately 850 cases have been reported in the literature. All cases share the chromosomal translocation t(11;22)(p13;q12), leading to the formation of the EWSR1-WT1 fusion gene. DSRCT characteristically arises in the abdomen or pelvis and carries a poor prognosis despite multimodal therapy. We report a rare and extensive case of abdominopelvic DSRCT with liver and peritoneal metastases in a 17-year-old Moroccan male, who presented with a progressive abdominal mass, pain, and hepatomegaly. The diagnosis was initially challenging due to the non-specific clinical presentation. The final diagnosis was established through liver biopsy and immunohistochemical analysis. The patient is currently undergoing treatment with a multidrug chemotherapy regimen.

Introduction: Necrosis of the round ligament of THE liver is an extremely rare cause of peritonitis, its nonspecific clinical signs frequently causing diagnostic difficulties. For this reason, contrast-enhanced multiphasic CT scan of the abdomen and pelvis is crucial in the diagnostic management.Case report: A 77-year-old male patient with epigastric pain and suspicion of acute cholecystitis was diagnosed with suspected necrosis of the round ligament of the liver on diagnostic imaging. The patient was qualified for surgical treatment. During the laparoscopic procedure, the necrosis of the round ligament of the liver was confirmed, and the necrotic ligament was subjected to laparoscopic resection. The patient was discharged home in good general condition on postoperative day 3.Conclusions: Necrosis of the round ligament of the liver is a rare but clinically significant entity that should be taken into consideration in the differential diagnosis of acute abdomen, particularly presenting with nonspecific symptoms. In most cases, the treatment of choice involves minimally invasive surgical treatment in the form of laparoscopic resection.

This report describes a 2-day-old male infant who presented with a perianal swelling since birth. The swelling was painless, exhibited a soft to firm consistency, and progressively increased in size over a period of 2 months. The perianal region is an uncommon location for rhabdomyosarcoma, accounting for approximately 2% of all tumours. Diagnostic workup included MRI of the abdomen, which revealed a 4.7 × 2.7 × 2.5 cm heterogeneous soft tissue mass in the perineum extending into the pelvis. Histopathological examination demonstrated lesional spindle and round cells with striations in the spindle cells. Immunohistochemical analysis showed diffuse positivity for desmin and MYOD1, with focal positivity for myogenin and a MKI67 proliferation index of 30%, leading to a final diagnosis of embryonal rhabdomyosarcoma with spindle cell morphology (ERMS). This study highlights the rarity of this presentation and underscores the critical role of immunohistochemical markers in the accurate diagnosis of ERMS at unusual locations.

Ewing sarcoma belongs to the family of undifferentiated small round cell sarcomas of bone and soft tissue. It is characterized by a gene fusion involving EWSR1 and an ETS-family transcription factor gene. In 85-96% of cases, a specific chromosomal translocation results in the EWSR1-FLI1 fusion gene, whose product functions as an oncogene essential for tumorigenesis. Ewing sarcoma is most common in adolescents and young adults. It primarily affects the diaphyses of long bones, the pelvis, and the axial skeleton, although extraosseous involvement is not uncommon. This is a highly malignant neoplasm, and in most cases, micrometastases are already present at the time of diagnosis. The treatment is multimodal and includes local therapy (surgery and/or radiotherapy) and systemic chemotherapy. One of the greatest therapeutic challenges remains the long-term systemic control of the disease. To improve overall survival - especially in high-risk patients - innovative treatment strategies are essential, as the potential for intensifying chemotherapy has reached its limit due to treatment-related toxicity. Both diagnostic and therapeutic management should take place in specialized sarcoma centers.

Ewing sarcoma (ES) is an aggressive tumor of the bone in young adults, commonly originating from the pelvis and long bones. It is characterized by chromosomal translocation t(11;22) (q24;q12), resulting in the EWSR1-FLI1 fusion gene. It presents with metastasis commonly to the lungs and other soft tissues. While the metastasis to lungs is common, orbital involvement with cranial involvement is exceptionally rare. The case highlights the need for the early detection and aggressive treatment in order to reduce mortality in patients ES. A 23-year-old South-Asian male presented with a 2 month history of progressive shortness of breath, 10 × 15 cm swelling on the left side of chest, and left-sided proptosis with diplopia. The early examination of the patient showed left-sided pleural effusion and ophthalmoplegia involving cranial nerves II, III, IV, VI, and V1. Computed Tomography (CT) identified a rib-origin mass extending into the pleura, and Magnetic Resonance Imaging (MRI) confirmed an orbital mass compressing the optic nerve. Pleural fluid analysis showed an exudative, lymphocyte-predominant picture with elevated Adenosine Deaminase (ADA), initially mimicking tuberculosis. However, a CT-guided biopsy of the chest mass confirmed small round blue cell histology. Immunohistochemistry (IHC) was positive for CD99 and NKX2.2 with a high Ki-67 index, confirming Ewing sarcoma. The patient was initiated on multimodal chemotherapy but succumbed to rapid disease progression and respiratory failure 2 months post-diagnosis. ES is a highly aggressive bone tumor. Early diagnosis with subsequent aggressive treatment particularly is very important for the survival of the patient. Immunohistochemistry can be helpful in the diagnosis of the tumor, especially in resource-limited countries. Timely intervention is important in Ewing sarcoma owing to the risk of metastasis. Radiation, chemotherapy, and surgical interventions can be used depending upon the patient's prognosis.

The functional morphology of the bovine bony pelvic floor has been studied little. This is a fascinating anatomical region as female animals have to adapt to various tensions caused by the reproduction cycle. In this study, based on the bony pelvic floors of five heifers and five cows, the average number of round and flat bone cells was detected in four pelvic floor regions, and correlations were calculated between the number of osteocytes and bone density. The number of flat cells per sample (33.0 ± 10.8) was significantly higher than the number of round cells (3.7 ± 1.7; p < 0.001). Cranially, the number of flat cells was the same in heifers and cows, while caudally, the number of flat cells was higher in cows. In both heifers and cows, bone mineral density was the lowest at the ischiopubic junction. However, while in heifers it was the same level caudally, in cows the bone mineral density was significantly higher (in heifers 0.55 g/cm2 and cows 1.53 g/cm2). Thus, bone adaptation was location-specific; in cows, the load was the greatest in the region of the ischia where dense bone mass accumulated, but in heifers, the tension was distributed more equally across the pelvic floor. Due to adaptation, multiparity did not lessen the bone density of the cows' pelvic floor. The correlation between bone density and the presence of bone cells in the bovine pelvic floor was weak and not significant and was surprising. Further studies with other histological methods may help to clarify these findings.

The World Health Organization introduced substantial revisions in the 2020 fifth edition of the classification system for bone and soft-tissue tumors, reorganizing what were previously called the Ewing sarcoma family of tumors or Ewing-like sarcomas into a new category of "undifferentiated small round cell sarcomas" based on molecular genetic characteristics. This reclassification established four distinct entities: Ewing sarcoma (ES), CIC-rearranged sarcoma, sarcoma with BCOR genetic alterations, and sarcoma with EWSR1-non-ETS fusion genes. Each subtype may demonstrate specific clinical, pathologic, and imaging features, with different treatment responses and prognoses. ES primarily affects children and young adults, with characteristic "moth-eaten" lytic bone destruction, aggressive periosteal reactions, and extensive surrounding soft-tissue masses. CIC-rearranged sarcomas typically manifest as well-circumscribed lobulated soft-tissue masses with extensive internal necrosis and hemorrhage but no calcification. Sarcomas with BCOR genetic alterations commonly occur in adolescent boys as osteolytic or sclerotic lesions in the long bones or the pelvis, often with calcification in the extraosseous component. Sarcomas with EWSR1-non-ETS fusion genes may manifest as osteolytic lesions with cortical expansion and saucer-like surface erosion in long bone diaphyses. Radiologic recognition of CIC-rearranged sarcomas enables oncologists to anticipate their aggressive nature and poor response to standard ES treatments, which may necessitate more intensive initial surgical interventions. In comparison, identifying BCOR-CCNB3 sarcomas through imaging allows clinicians to inform patients of their potentially more favorable outcomes compared with those of ES while still applying appropriate comprehensive treatment approaches. The authors provide an overview of the clinical features, pathologic findings, imaging characteristics, differential diagnosis, and treatment outcomes of each entity. [©]RSNA, 2026.

Background: Pelvic venous disorders (PeVD) are associated with chronic pelvic pain and varicose veins due to venous insufficiency and pooling in the pelvis. Despite increasing interest, there is a lack of widely accepted diagnostic algorithms and validated criteria, which complicates diagnosis and management. This study aimed to develop and validate a diagnostic and therapeutic algorithm for PeVD using expert consensus. Materials and methods: An independent Advisory Board (AB) of 11 Italian specialists (gynaecologist, radiologists, vascular surgeons, and angiologists) was convened. A literature review informed the development of a draft algorithm. Three Delphi survey rounds were conducted, with online and in-person discussions, and a consensus threshold set at ≥70%. Results: All 11 AB members completed the first two survey rounds, and eight completed the third. The median number of diagnosed and treated PeVD cases per expert was 20 and 12 per year, respectively. The group agreed on classifying PeVD into Pelvic Congestion Syndrome (PCS) and compressive/obstructive syndromes. Endovascular therapy was recognised as standard of care: pelvic embolisation for PCS, stenting for obstructive lesions, and combined approaches when both are present. Clinical success was defined as subjective symptom improvement assessed 3-6 months post-procedure. Treatment failure warranted re-evaluation and possible reintervention. Surgical treatment was considered only when conservative and endovascular options failed (37.5% agree, 50% neutral). Conclusions: This Delphi-based consensus produced a validated, multidisciplinary algorithm for the diagnosis and treatment of PeVD. It highlights the need for standardised clinical pathways, but further validation by a broader expert community is warranted.