Pediatric Hepatic Cystic Lesions: Differential Diagnosis and Multimodality Imaging Approach.

When a pediatric hepatic cystic lesion is identified at imaging, the differential diagnosis may be broad, including developmental, infectious, neoplastic, and posttraumatic or iatrogenic causes. The location of a cystic lesion and its number, size, composition, and relationship to the biliary system are features that help in narrowing the differential diagnosis. An incidentally detected simple hepatic cyst is the most commonly encountered. Ciliated foregut cysts are typically located in hepatic segment IVa. The presence of multiple cysts should raise suspicion for fibropolycystic liver disease, a group of related lesions-including biliary hamartoma and choledochal cyst-caused by abnormal embryologic development of the ductal plate. Communication of the cystic lesion with the biliary tree can confirm the diagnosis of choledochal cyst. In a neonate with jaundice, a cystic lesion at the porta hepatis should raise suspicion for choledochal cyst versus cystic biliary atresia. Hepatic abscess can appear cystlike, though typically with internal contents. In an immunocompromised child, multiple cystlike lesions should raise concern for fungal microabscesses. A complex cystic mass in a young child should raise suspicion for mesenchymal hamartoma, which can evolve into undifferentiated embryonal sarcoma if untreated. Hepatic hematoma and biloma can appear cystlike in children with a history of trauma or recent intervention. In neonates with an umbilical vein catheter (UVC), an intrahepatic cyst along the course of the UVC should raise concern for infusate extravasation. Familiarity with imaging findings and clinical features is essential for achieving accurate diagnosis of pediatric hepatic cystic lesions, which in turn can guide appropriate clinical management. Online supplemental material is available for this article. ©RSNA, 2022.

Incidence and importance of portal venous gas in children with hypertrophic pyloric stenosis.

BACKGROUND: Hypertrophic pyloric stenosis (HPS) is a common cause of gastric outlet obstruction in young infants. Infants with HPS present with projectile vomiting, sometimes have electrolyte abnormalities and typically undergo pyloromyotomy to alleviate the obstruction. Abdominal US is the gold standard imaging study for diagnosis. Case reports of incidental hepatic portal venous gas have been reported in infants with HPS; however, no large studies have been conducted to determine the incidence or possible clinical implications of this finding. OBJECTIVE: To assess the incidence of portal venous gas in infants with HPS and to determine whether the presence of this gas in infants with HPS indicates a more unstable patient, increased length of stay or worse outcome. MATERIALS AND METHODS: We conducted a retrospective review of sonographic reports containing "pyloric stenosis," excluding negative descriptor, at a tertiary-care children's hospital from November 2010 to September 2017. Data collected included pyloric thickness/length, liver evaluation, portal venous gas, any additional imaging, demographics, symptomatology days, electrolyte abnormality, and length of hospital stay. RESULTS: In a 7-year period, 545 US exams were positive for HPS. Of these, 334 exams included enough hepatic parenchyma to evaluate for portal venous gas. Infants in 6 of the 334 exams demonstrated portal venous gas (1.8%). Clinical presentation (length of symptoms and electrolyte abnormalities), demographics (male predominance and age at presentation) and imaging characteristics (pyloric thickness and length) were similar for the HPS groups with and without portal venous gas. There was no significant difference in outcome or length of hospital stay. CONCLUSION: Visualization of portal venous gas in infants with HPS is not rare and appears benign, without need for further imaging. Portal venous gas in infants with HPS does not portend a more severe patient presentation or outcome.

Congenital Limb Overgrowth Syndromes Associated with Vascular Anomalies.

Congenital limb length discrepancy disorders are frequently associated with a variety of vascular anomalies and have unique genetic and phenotypic features. Many of these syndromes have been linked to sporadic somatic mosaicism involving mutations of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway, which has an important role in tissue growth and angiogenesis. Radiologists who are aware of congenital limb length discrepancies can make specific diagnoses based on imaging findings. Although genetic confirmation is necessary for a definitive diagnosis, the radiologist serves as a central figure in the identification and treatment of these disorders. The clinical presentations, diagnostic and imaging workups, and treatment options available for patients with Klippel-Trenaunay syndrome, CLOVES (congenital lipomatous overgrowth, vascular anomalies, epidermal nevi, and scoliosis/spinal deformities) syndrome, fibroadipose vascular anomaly, phosphatase and tensin homolog mutation spectrum, Parkes-Weber syndrome, and Proteus syndrome are reviewed. ©RSNA, 2019.

Malignant degeneration of pulmonary juvenile-onset recurrent respiratory papillomatosis.

Juvenile-onset recurrent respiratory papillomatosis (JORRP) is a rare disease associated with the human papilloma virus (HPV) in which papillomas form along the aerodigestive tract in children. Pulmonary involvement is uncommon, but associated with worse clinical outcomes, including the rare complication of malignant transformation. We present a patient with JORRP in which lung disease underwent malignant transformation during adolescence. Our goal is to raise awareness of the potential for malignant transformation in children, as well as to familiarize pediatric radiologists with imaging features of malignant lung disease in JORRP. We advocate for the identification of the subgroup of JORPP patients with pulmonary disease who, due to increased risk for malignant transformation, may benefit from closer clinical and imaging surveillance by a multidisciplinary team.

Use of the star sign to diagnose internal fistulas in pediatric patients with penetrating Crohn disease by MR enterography.

Development of internal fistula due to extramural spread of inflammatory bowel disease is a characteristic feature of penetrating disease in patients with Crohn disease. The "star sign" is a radiological finding of internal fistula that has previously been described in the gastroenterology literature in adult Crohn disease patients undergoing MR enteroclysis. The goal of this paper is to review the clinical and imaging features of penetrating disease in pediatric Crohn disease patients, highlighting the star sign as a useful diagnostic tool for diagnosing internal fistula in children by MR enterography. The recognition of penetrating complications by MR imaging can have important therapeutic and prognostic implications.

NUT midline carcinoma: an imaging case series and review of literature.

BACKGROUND: NUT midline carcinoma is a rare and aggressive tumor that has primarily been reported in children and young adults. The tumor is characterized by a rearrangement on the nuclear protein in testis (NUT) gene, located on chromosome 15q14, resulting in the BRD4-NUT fusion oncogene. This carcinoma most commonly presents in the midline and displays an invariably lethal clinical course. OBJECTIVE: To highlight the imaging features of NUT midline carcinoma. MATERIALS AND METHODS: IRB approval was obtained for chart review. We retrospectively reviewed the chart and imaging studies of three children. All three cases were diagnosed by karyotyping and confirmed by fluorescence in situ hybridization (FISH). Cross-sectional imaging including CT, MRI and, in one patient, PET was available for review. RESULTS: Two out of three children presented with midline and multifocal disease. The third case had a medial left thigh mass and no metastatic disease at initial presentation. The common imaging features include heterogeneous low density on CT and T1 hypointensity and low-level T2 hyperintensity on MRI with heterogeneous enhancement. All cases were confirmed pathologically and by molecular studies. CONCLUSION: NUT midline carcinoma usually presents in the midline, either in the head, neck or chest. We present three cases with the bulk of the tumor below the diaphragm, which is seen in the minority of patients with NUT midline carcinoma, according to the available literature. Metastatic disease is common at initial presentation and can be quite extensive. The most striking feature of this disease is its aggressive nature with exponential interval growth of tumor.