Objective: To investigate the clinicopathological and molecular genetic characteristics of pediatric tumors with DICER1 mutations. Methods: A total of 90 patients diagnosed with various types of pediatric tumors at Beijing Children's Hospital, Capital Medical University, Beijing, China from July 2023 to September 2025 were included in this study. PCR amplification and Sanger sequencing were performed to detect the coding-region mutations of the DICER1 gene. The clinical, histopathological, and molecular genetic features of the cases with DICER1 mutation were then analyzed. Results: Among the 90 patients, 39 were male and 51 were female, with an age of onset ranging from 1 month to 17 years [median 7.13 (2.77, 10.37) years]. DICER1 mutations were detected in 37 patients (37/90, 41.1%). Among them, 9 cases harbored one mutation [6 pleuropulmonary blastomas (PPBs), 2 sex cord stromal tumors (SCSTs), and 1 cystic nephroma (CN)], 27 cases carried two mutations [10 PPBs, 3 anaplastic sarcomas of the kidney (ASKs), 3 SCSTs, 3 thyroid adenoma, 2 nodular thyroid goiters, 2 thyroid follicular lesions, 2 CN, 1 embryonal rhabdomyosarcoma, and 1 case with multiple primary tumors], and 1 case exhibited three mutations (bilateral ASKs). Despite variations in the site of origin, DICER1-mutant tumors shared several morphological features. Grossly, they presented as multilocular cystic, cystic-solid to solid masses. Microscopically, they exhibited a subepithelial layer of mesenchymal cells, with focal rhabdomyoblastic/chondroid/chondrosarcomatous differentiation, as well as cellular anaplasia. Germline testing using peripheral blood in the 31 patients with DICER1 mutation confirmed germline origin in 61.3% (19/31) of them. Parental analysis (n=12) demonstrated genetic inheritance in 8 cases, predominantly from families with tumor history. Germline variants scattered throughout DICER1 and consisted of loss-of-function mutations (nonsense, frameshift, and splice-site). Somatic mutations showed distinct clustering in exons 24 and 25 hotspots (codons 1705, 1709, 1809, 1810 and 1813), primarily missense variants. Notably, one multiple primary tumor case harbored a somatic mosaic p.E1705K mutation. Conclusions: DICER1 mutations are frequently detected in pediatric PPB, CN, SCST, ASK, nodular thyroid goiter, thyroid adenoma, and genitourinary rhabdomyosarcoma, which often represent as the index case of DICER1 syndrome. Performing DICER1 mutation testing in these patients not only facilitates tumor diagnosis and secondary cancer surveillance, but also enables the comprehensive genetic risk assessment and management for patient's family members.

BACKGROUND The special physiological changes during pregnancy pose a huge challenge to the diagnosis of cervical cancer in pregnancy (CCIP). However, due to the poor prognosis of advanced-stage CCIP, there is currently no consensus or guideline for diagnosis and treatment. CASE SUMMARY In this case report, we presented the case of a 30-year-old woman at 30 weeks of gestation who presented with irregular vaginal bleeding and was admitted to a local hospital at 35 weeks of gestation with a sudden gush of fluid and underwent a C-section. During the surgery, a rotten fish-like solid mass in the lower segment of the posterior wall of the uterus was excised for biopsy. The patient was referred to our hospital because she experienced heavy vaginal bleeding 13 days after one chemotherapy session. The solid mass was initially misdiagnosed as uterine clear-cell carcinoma at local hospital but later confirmed as cervical adenosquamous carcinoma by a multidisciplinary team. Three months posttreatment, she succumbed to multiple tumor metastases. The infant was healthy at the latest 2-year follow-up. CONCLUSION Obstetricians should expand differential diagnoses when obstetric factors cannot explain symptoms of persistent vaginal bleeding during pregnancy. Atypical and insidious clinical presentations are often concealed by physiological changes during pregnancy, which may increase the difficulty of diagnosis and result in misdiagnosis.

Follicular membrane cell tumor/fibroadenoma is a tumor originating from the ovarian stromal cells, typically producing estrogen that may cause symptoms such as postmenopausal bleeding or endometrial hyperplasia. This tumor is usually benign, but rare malignant forms exist, appearing as a solid ovarian mass on imaging and are considered for surgical removal (oophorectomy or cystectomy) if symptomatic. When a patient has ovarian fibroids, pleural effusion, and ascites, a diagnosis of Meigs syndrome needs to be considered. In this case, we report a patient with frequent urination, urgency, and nocturia who underwent [ 18 F]FDG and [ 18 F]FAPI-42 PET/CT scan to look for a lesion, which was finally detected in the left adnexa by the latter.

Background Fluid overload-associated large B-cell lymphoma (FO-LBCL) is an exceptionally rare lymphoma characterized by predominant involvement of serous body cavities—such as the pleura, peritoneum, and pericardium—in the absence of a solid tumor mass. Its low incidence and nonspecific clinical presentation, which often includes symptoms like dyspnea due to effusion, contribute to diagnostic challenges in early stages. This study aims to address current gaps in the understanding of FO-LBCL by reporting two new cases and reviewing the clinical features, treatment regimens, and outcomes of 57 documented patients. Furthermore, through a detailed analysis of FO-LBCL characteristics, this work discusses relevant differential diagnoses and potential treatment strategies. Methods A literature search of PubMed and Web of Science was performed using the following search queries: (1) “Fluid overload-associated large B-cell lymphoma” OR “FO-LBC”; (2) “Human herpesvirus 8-unrelated” AND “effusion lymphoma”; (3) “HHV8-unrelated” AND “effusion lymphoma”. Results This study included a total of 57 patients. Fluid accumulation most commonly affected the pleural cavity (84.2%), followed by the pericardial (31.6%) and peritoneal (21.1%) cavities. The predominant clinical manifestation was dyspnea (55.8%). Chemotherapy was the primary treatment modality (56.1%), with the R-CHOP regimen representing the most commonly administered protocol. CD20 expression was the most significant favorable prognostic factor (P = 6×10-7). Other factors associated with improved survival included the absence of CD138 expression (P = 0.0009), age ≥ 65 years (P = 0.0015), LDH ≤ 500 U/L (P = 0.0064), the presence of pleural effusion (P = 0.0099), and CD79a expression (P = 0.0411). Treatment with rituximabcontaining chemotherapy regimens was also a significant favorable factor (P = 0.0036). Conclusions FO-LBCL often presents with dyspnea caused by fluid effusion. Routine laboratory tests typically show no significant abnormalities, making timely pathological examination essential for a definitive diagnosis. Clinicians should enhance their understanding of FO-LBCL characteristics to improve early diagnostic accuracy. It is crucial to select appropriate treatment strategies based on prognostic factors.

We aimed to study the feasibility and automation of intracorporeal lung specimen dissolution using NaOH to decrease specimen extraction trauma. Twenty-three cadaveric porcine lungs were weighed, cannulated, placed in laparoscopic tissue extraction sacs, and submerged in water baths (37 °C). Lungs were digested for 6 to 36 h with dissolution fluid replacement through various cannulation strategies. Dissolution was quantified by changes in solid mass and structural and histologic integrities. After optimization, we performed 24-hour lung dissolution in a cadaveric porcine model. Next, a system was built using polyvinyl chloride, solenoid valves, water flow sensors, tubing, a vacuum pump, and an Arduino UNO (Monza, Italy). Flow tests were performed. System feasibility and safety were tested. A vacuum chamber was added for gentle agitation to the digestion solution through fluid oscillation. Functional tests were repeated. There were no containment failures. Compared with saline, NaOH exhibited significant dissolution by 6 h (P < 0.001) progressing to a port-extractable, jelly-like material by 24 h (<20% initial mass). The degeneration of parenchymal histology correlated with NaOH exposure (r = 0.98, P = 0.02). Neither enzyme use (P = 0.3) nor specimen vascular cannulation (P = 0.15) improved dissolution compared with bathing. At 24 h, the clinical emulation model demonstrated no leaks and lung tissue effects proportionate to volume of delivered lye. During the flow tests, inflow was more precise, with minimal deviation. Outflow was more accurate, with measurements closer to the true value. The system passed 6-hour safety tests without leaks, with and without the vacuum chamber. These preliminary results suggest that automation of intracorporeal lung specimen digestion is feasible.

Flow regimes of vertical upflow for slightly cohesive Geldart A powders at high solids mass flux (Gs≳ 500 kg/m2s) are not fully resolved. In particular, Dense Suspension Upflow (DSU) as a distinct flow regime and its transition boundaries are not broadly accepted. Furthermore, the locus of the pressure gradient minimum, which is the broadly accepted dense–dilute transition at low Gs, requires validation at high Gs. In our recent work, by adapting the phase map of Wirth and by Eulerian modeling, DSU was defined as a distinct flow regime with gross upflow of solids and with granular temperature at the wall greater than that in the bulk. This study has further validated the definition of DSU and its transition boundaries by extending the modeling to areas not fully explored in the earlier work. Furthermore, this study has identified (a) the possibility of a phase of DSU between fast fluidization and turbulent regime at all Gs; and (b) the need to review the suitability of the locus of the pressure gradient minimum as the dense–dilute transition at high Gs. Additionally, our work has demonstrated (a) a new provisional correlation that the upper transport velocity for Geldart A powders is significantly greater than hitherto predicted; and (b) the slip velocity in the transport regimes increases with Gs to peak within fast fluidization and falls thereafter to attain low multiples of the terminal settling velocity within DSU.

Sodium-ion (Na-ion) batteries offer a promising, cost-effective, and more environmentally abundant alternative to lithium-ion batteries, making them a key focus of next-generation energy storage research. Furthermore, hard carbon stands out as a promising anode material for Na-ion batteries due to its favorable capacity and cycling stability [1]. However, achieving optimal electrochemical performance hinges on a careful understanding of how electrode manufacturing parameters affect the electrode’s microstructural and transport properties. The work presents a comprehensive study on the influence of solid content, mass loading, and calendering on the porosity and tortuosity factor of hard carbon electrodes. By systematically adjusting these manufacturing parameters, we assess the changes in the electrode microstructure, including pore size distribution and interconnectivity, which directly impact ionic and electronic transport pathways [2].We evaluated the electrochemical performance of these electrodes in both half-cells with Na metal and in full-cells with a polyanionic cathode. Through galvanostatic cycling and rate capability tests, we found that an optimal balance of solid content and mass loading, coupled with a controlled calendering procedure, can significantly enhance sodium storage kinetics and reduce polarization losses. The detailed results will be discussed in the presentation.These results show how carefully designing the electrode can bring out the full potential of hard carbon in Na-ion batteries. By explaining how different processing steps affect the electrode’s microstructure and the way ions move through it, this work paves the way for making hard carbon anodes at an industrial scale. The improved electrodes hold great promise for next-generation energy storage, offering a more affordable and eco-friendly solution in Na-ion battery technology. The acquired experimental data is being used to support the development of digital models of the manufacturing process being carried out in our research group [3]. Reference Dou et al., Hard Carbons for Sodium-Ion Batteries: Structure, Analysis, Sustainability, and Electrochemistry, Mater. Today 2019, 23, 87–104.Raj and A. A. Franco, Understanding the Manufacturing Processability of Hard Carbon Electrodes to optimize the electrochemical performance of Na-ion battery Cells, paper to be submitted (2025).F. Troncoso, F.M. Zanotto, D. E. Galvez-Aranda, D. Zapata-Dominguez, L. Denisart, A.A. Franco, "The ARTISTIC Battery Manufacturing Digitalization Initiative: From Fundamental Research to Industrialization", Batteries & Supercaps 8(1) (2025) e202400385.

To evaluate diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) for the prenatal differentiation of fetal adrenal neuroblastoma (NB) from benign masses. This retrospective study analyzed prenatal magnetic resonance imaging/DWI data from 54 pregnant women (59 adrenal masses) with a suspected solid adrenal mass on ultrasound. Cases with severe malformations or poor image quality were excluded. The minimum ADC (ADCmin), mean ADC (ADCmean), and relative ADC (rADC) values within the tumor solid components were measured. Group comparisons and receiver operating characteristic (ROC) curve analysis were performed to assess the diagnostic performance. Eighteen masses (30.5%) were classified as NB, while the remaining 41 (69.5%) were benign, including sequestration, hematoma, and teratoma. The NB group showed significantly greater gestational age at detection (mean age, 35 weeks), higher right adrenal prevalence (66.7%), and larger maximum diameters (3.6 cm vs. 2.4 cm; P < 0.01) compared to the non-NB group. The ADCmin, ADCmean, and rADC were significantly lower in the NB group (P < 0.001). ROC analysis identified ADCmin as the optimal diagnostic parameter (area under the curve = 0.981). An ADCmin threshold of 1382 μm2/s yielded 97.56% sensitivity and 100% specificity. These findings indicate that the quantitative DWI parameter ADCmin can reliably differentiate fetal adrenal NB from benign lesions prenatally. Its high sensitivity and specificity may provide an objective basis for clinical decisions and optimized perinatal management.

Solitary fibrous tumors (SFT) are a rare neoplasm of mesenchymal origin. SFT was previously described primarily in the pleura and meninges; however, extrapleural and extra-meningeal SFT have been reported in almost every anatomic site and account for up to 40% of cases. The most significant histologic findings of SFT include spindle cell proliferation in a "pattern-less pattern", dilated and branching "staghorn"-like vasculature, and ropey collagen deposition. However, these findings are not consistently present in every case of SFT and may also be seen in other diseases. SFT has a characteristic NAB2::STAT6 gene fusion and nuclear overexpression of STAT6. The rarity of the disease, broad range of differential diagnoses, and wide spectrum of cytomorphological and histologic findings make the diagnosis of extrapleural SFT, especially on a fine needle aspiration (FNA) specimen, challenging. Recognizing and including this entity in the differential is necessary before the final diagnosis may be achieved through proper immunohistochemical and molecular workup. In this paper, we present two cases of extrapleural SFT with unusual locations: the first is a primary SFT present in a parotid gland and the second is a metastatic SFT present as two solid pancreatic masses.

Rationale:Myeloid sarcoma (MS) is an extramedullary solid tumor composed of myeloid progenitor cells, which is rare in non-leukemic patients. Our research aims to enhance the understanding of the challenges in diagnostic and therapeutic of MS.Patient concerns:A 61-year-old male was admitted to hospital presenting with “malignant pleural tumor diagnosed 2 months prior, accompanied by chest distress for over a month.”Diagnosis:Cytological analysis of pleural effusion confirmed malignant cells and supported by immunohistochemical results. Bone marrow biopsy showed 83.5% blasts, with flow cytometry indicating 56.32% tumor cells and the presence of the AML1–ETO fusion gene (FLT3−ITD+). Cytogenetic analysis revealed complex karyotypic abnormalities.Interventions and outcomes:After treated with the Idarubicin-Cytarabine regimen and intrapleural cisplatin, bone marrow biopsy revealed residual tumor cells (0.46%). Further consolidation with the Idarubicin-Cytarabine regimen and additional cycles of azacitidine plus venetoclax and cytarabine plus venetoclax were administered. Unfortunately, the patient passed away following disease progression.Lessons:Although pleural myeloid sarcoma is extremely rare, it must be included in the differential diagnosis for unexplained solid pleural masses, particularly when accompanied by pleural effusion. Upon diagnosis, comprehensive staging investigations, including bone marrow biopsy and flow cytometry, must be performed immediately. The successful management of such complex cases relies on the close collaboration of a multidisciplinary team, including radiologists, pathologists, hematologists, and thoracic surgeons. Radiologists identify atypical imaging features, pathologists confirm the diagnosis through precise immunophenotyping, and ultimately, hematologists formulate and execute the correct treatment plan.

Abstract Solid pancreatic mass lesions pose a substantial diagnostic challenge, especially in resource-limited settings. Endoscopic ultrasound (EUS)-guided fine-needle aspiration (EUS-FNA) and fine-needle biopsy (EUS-FNB) are both widely utilized, yet comparative data on their performance under constrained conditions remain limited. In this prospective, randomized, single-center pilot study, patients with suspected solid pancreatic lesions were randomized to undergo either EUS-FNA (n = 20) or EUS-FNB (n = 21). Diagnostic accuracy, sensitivity, specificity, sample cellularity, technical success, adverse events, and total cost (needle + pathological processing) were assessed. Forty-one patients were randomized. Diagnostic accuracy was slightly higher in the FNB group (95.2%) compared to the FNA group (90%). Sensitivity was similar for FNB (92.9%) and FNA (92.3%), but specificity was greater with FNB (100% vs. 85.7%). Technical success was 100% in both arms, with only minor adverse events reported. Most samples demonstrated moderate to high cellularity in both arms. The estimated cost per procedure was INR 22,200 for FNA and INR 27,400 for FNB. EUS-FNB demonstrated slightly improved diagnostic yield but was expensive compared to FNA. In resource-limited settings, EUS-FNA offers a cost-effective and reliable first-line diagnostic option. Larger multicenter studies are needed to guide context-appropriate needle selection strategies.

Abstract BACKGROUND Primary solid brain tumors, including glioblastomas, are rare in persons with Down syndrome, who are typically more predisposed to hematologic malignancies than solid tumors. The role of trisomy 21 in neuro-oncologic pathophysiology remains poorly understood. We report a rare case of glioblastoma, IDH-wild type, in a young adult with Down syndrome presenting with new-onset focal seizures. CASE DESCRIPTION A 26-year-old male with Down syndrome and no prior neurologic complaints presented with a one-month progression of right temporal headaches, irritability, and behavioral changes, eventually developing focal motor seizures and left-sided hemiparesis. Cranial MRI revealed a mixed cystic solid mass in the right temporal lobe with calcifications and perilesional edema. Electroencephalography showed focal slowing and epileptiform discharges over the right temporal region. The patient underwent craniotomy and safe maximal resection of the tumor. Histopathologic analysis revealed glioblastoma, IDH-wild type. Immunohistochemistry was positive for ATRX, GFAP, OLIG2, and S100, and negative for IDH1, EMA, and CD99. Despite referral to oncology service, the family opted palliative care. The patient was discharged medically stable with outpatient follow-up. DISCUSSION Glioblastoma is exceedingly rare in patients with Down syndrome, possibly due to overexpression of tumor-suppressor genes on chromosome 21. This case highlights the importance of considering structural intracranial pathology in patients with neurodevelopmental disorders who develop new-onset seizures or behavioral decline. Diagnostic delay may occur due to attribution of symptoms to baseline cognitive impairment. Early neurology consult and imaging is critical in such cases. CONCLUSION This case illustrates a highly unusual occurrence of glioblastoma in Down syndrome, a population typically considered at lower risk for solid brain tumors. The importance of clinical vigilance and prompt neuroimaging in patients who present with atypical neurologic symptoms are highlighted here. This case contributes to the sparse literature and raises important questions about tumor pathogenesis in trisomy 21.

The paper discusses methodological aspects of studying the breaking and seismic effects of blasting at a test site and the specific features of using the smooth particle hydrodynamics (SPH) method to assess the patterns of parameter changes in solid and fractured rock masses. The dependence of the resulting vector velocity of ground displacement on the detonation velocity was analyzed based on the results of many years of field tests of charges with different energy densities and the detonation velocities ranging from 1.8 to 8.5 km/s, as well as numerical modeling using the smoothed particle hydrodynamics method. It has been established that the dependence of the ground displacement velocity on the detonation velocity of the charges and the energy release velocity is polynomial in nature. This indicates the complex, nonlinear nature of the process of energy release by the explosive and its absorption by a heterogeneous rock mass as it moves away from the charge. This pattern implies the possibility of extremes, i.e. areas of maximum or minimum effect, which is important to consider when forecasting and optimizing parameters of the blasting operations.

Various halo- and dihalo-ethylenes were observed to transform into solid white masses over the period of 1838 to 1872. The greatest contribution of Victor Regnault (1810-1878) to the chemistry detailed herein was the initial synthesis of vinyl halides and dichloroethylene. He was also the first to observe the “molecular transformation” of interest here, that is, a polymerization in the modern sense. This was the polymerization of dichloroethylene or vinylidene chloride, the first known example of the polymerization of a vinyl halide species and the earliest known example of photopolymerization. Eugen Baumann (1846-1896) observed the polymerization of vinyl chloride, the last observed of the transformations presented in the current article. While Baumann can be credited with the first observation of vinyl chloride polymerization, his more important contributions were the determination that this transformation was an action of light and that this reaction was a general aspect of vinyl halides as a class of compounds, rather than isolated examples of an interesting phenomenon.

Epidemiologically, hypothalamic neurosarcoidosis occurs in middle-aged individuals with pituitary dysfunction. Older patients rarely develop hypothalamic neurosarcoidosis with incomplete hemiparesis. MRI in a 75-year-old man with incomplete left hemiparesis revealed an enhanced mass lesion in the hypothalamus and tuber cinereum, with enhanced satellite nodules in the right basal ganglia. Transcortical neuroendoscopic biopsy was performed to confirm the pathological diagnosis. Narrow-band imaging (NBI) of the mass lesion revealed an abnormal vascular structure with a cyan color. A biopsy was successfully performed, and pathological evaluation and additional analyses led to a final diagnosis of sarcoidosis. Steroid treatment was administered, and follow-up MRI revealed that almost all lesions had disappeared, with resolution of the left hemiparesis. Neurosarcoidosis should be considered as a differential diagnosis of multiple solid cerebral mass lesions in older patients. Detecting characteristic vascular constructions using NBI allows for the accurate identification of lesions. https://thejns.org/doi/10.3171/CASE25578.

Precipitation-based versus filtration-based liquid-based cytology in EUS-FNB specimens of solid pancreatic masses: a prospective, randomized trial.

Abstract Introduction/Objective Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a standard technique for diagnosing solid pancreatic masses, but its cytologic yield and diagnostic accuracy can be limited. Fine needle biopsy (FNB) needles have been introduced to improve tissue sampling either alone or combined with FNA. This study evaluates whether adding FNB to FNA improves diagnostic performance. Methods/Case Report We retrospectively reviewed 40 consecutive cases of EUS-guided sampling of solid pancreatic masses at a single center from 2021 to 2025. Cases were divided into two groups: FNA alone (n = 19) and combined FNA+FNB (n = 21). Final diagnoses were classified as benign or malignant. Diagnostic yield for malignancy was compared using Fisher’s Exact Test. Results The combined FNA+FNB group showed a significantly higher malignant diagnostic yield (15/21; 71.4%) than the FNA-alone group (6/19; 31.6%). Statistical analysis confirmed that adding FNB significantly improves malignant detection (p = 0.014). Conclusion Adding FNB to EUS-FNA significantly enhances diagnostic accuracy for malignant pancreatic masses. Incorporating FNB with FNA may optimize diagnostic yield and improve patient management in suspected solid pancreatic neoplasms.

A BSTRACT Uterine leiomyomas stand as the predominant benign pelvic tumours among women. The diagnosis and management of a giant leiomyoma can be challenging. Herein, we are reporting the case of a 44-year-old multiparous woman who presented with huge abdominal distention. On imaging, a huge solid cystic mass of 42 × 25.7 × 35.8 cm was occupying the whole abdominopelvic cavity. After evaluation and multidisciplinary discussion, the patient was taken up for surgery. A giant grey-white solid cystic mass attached to the fundus and body of the uterus was found. Intraoperatively, around 23 litres of clear seromucinous fluid was gradually drained from the mass. After decompression of the mass and careful dissection, a hysterectomy was performed. Bilateral ovaries and fallopian tubes were grossly normal. The histopathology established the diagnosis of Giant cystic leiomyoma with massive cystic degeneration. Such massive cystic degeneration in uterine leiomyoma is an exceedingly rare finding.

Abstract Introduction/Objective Ewing Sarcoma (EWS) is a member of the Ewing Sarcoma Family Tumors (ESFT) of malignant small round cell sarcomas typically arising in the bones/soft tissues of children and young adults. Primary extraskeletal EWS arising breast is extremely rare, with less than twenty cases reported to date. EWS can mimic both the more common breast malignancies or benign conditions clinically and radiologically. We present a rare case of primary breast EWS in a young woman with initial imaging findings suggestive of a benign hematoma. Methods/Case Report A 25-year-old woman presented with a palpable progressively enlarging breast mass following a crush injury. Initial ultrasound revealed a 3.5 × 2.0 × 3.3 cm multiseptated cystic mass, interpreted as a possible hematoma. Follow-up ultrasound performed after four months revealed a persistent cystic and solid mass with rapid growth to 5.6 × 3.9 x 5.2 cm with new internal vascularity. A biopsy was performed for diagnosis. Results Histology showed uniform small round cells with scant cytoplasm. Immunohistochemistry demonstrated diffuse CD99 and FLI-1 positivity, with focal p63 staining. The tumor was negative for epithelial, neuroendocrine, melanocytic, and hematopoietic markers. FISH confirmed EWSR1 gene rearrangement. The patient is currently on sarcoma-based therapy. Conclusion Primary breast EWS is exceedingly rare and poses significant diagnostic challenges. Non-specific imaging coupled with trauma history could mislead clinicians. Awareness of this entity is essential for early diagnosis, appropriate management, and improved outcomes.

The osteolytic skull lesions of Langerhans cell histiocytosis (LCH) in children are typically solid and slow-growing masses. A history of minor head trauma has been associated with the development and enlargement of LCH skull lesions in some children; head trauma has also rarely been associated with epidural hematoma from skull lesions of LCH. Isolated expansile cystic hemorrhagic skull lesions in LCH have been documented before in five cases, with two having a history of minor head trauma and one regressing spontaneously. Parotid gland involvement in LCH among children is rare, typically occurs as part of a disseminated multisystem disease, and is characterized by bilateral diffuse glandular enlargement. A unilateral parotid gland hematoma developing after minor trauma as the initial presentation of LCH has not been previously reported. Here, we describe a case of a 3-year-old boy with cystic hemorrhagic LCH lesions of the skull associated with minor head trauma. The skull lesions showed spontaneous regression before LCH was diagnosed through cytopathologic re-evaluation of a prior trauma-related unilateral parotid gland hematoma. A literature review of the imaging and clinical features of hemorrhagic skull lesions in LCH is presented.