Patterns of Growth of Tumors in Li-Fraumeni Syndrome by Imaging: A Case Series.

Although tumors of Li-Fraumeni syndrome (LFS) have a premalignant or dormant phase that could be exploited by early imaging detection, this has been underevaluated in the literature. We present a case series of patients with LFS followed by imaging over time to highlight patterns of growth of tumors and hotspots of missed tumors in this population. Clinical and imaging features were available for 29 tumors of 24 carriers of a germline TP53 pathogenic variant, developed between 1999 and 2023 were retrospectively reviewed in a single tertiary pediatric center. Imaging characteristics of tumors were evaluated with MRI, CT, and radiographs. Local invasion, time interval for developing primary cancer, and/or recurrent disease and metastasis, and factors that delayed the tumor diagnosis were assessed. In patients with multiple tumors the median time intervals for development of first, second, and third primary cancers were 45.9, 79.8, and 28.1 months, respectively. Hotspots of missed tumors included superficial soft tissues, areas close to bones, on the scalp, in tissues around the adrenal region and in small hypodense lesions on brain CT. In conclusion, the pattern of growth of tumors is variable and erratic in LFS patients with some tumors presenting with a dormant pattern.

Diagnostic accuracy of imaging approaches for early tumor detection in children with Li-Fraumeni syndrome.

BACKGROUND: The Toronto protocol for cancer surveillance in children with Li-Fraumeni syndrome has been adopted worldwide. OBJECTIVE: To assess the diagnostic accuracy of the imaging used in this protocol. MATERIALS AND METHODS: We conducted a blinded retrospective review of imaging modalities in 31 pediatric patients. We compared imaging findings with the reference standards, which consisted of (1) histopathological diagnosis, (2) corresponding dedicated imaging or subsequent surveillance imaging or (3) clinical outcomes. We individually analyzed each modality's diagnostic performance for cancer detection and assessed it on a per-study basis for chest and abdominal regional whole-body MRI (n=115 each), brain MRI (n=101) and abdominal/pelvic US (n=292), and on a per-lesion basis for skeleton/soft tissues on whole-body MRI (n=140). RESULTS: Of 763 studies/lesions, approximately 80% had reference standards that identified 4 (0.7%) true-positive, 523 (85.3%) true-negative, 5 (0.8%) false-positive, 3 (0.5%) false-negative and 78 (12.7%) indeterminate results. There were 3 true-positives on whole-body MRI and 1 true-positive on brain MRI as well as 3 false-negatives on whole-body MRI. Sensitivities and specificities of tumor diagnosis using a worst-case scenario analysis were, respectively, 40.0% (95% confidence interval [CI]: 7.3%, 83.0%) and 38.2% (95% CI: 29.2%, 48.0%) for skeleton/soft tissues on whole-body MRI; sensitivity non-available and 97.8% (95% CI: 91.4%, 99.6%) for chest regional whole-body MRI; 100.0% (95% CI: 5.5%, 100.0%) and 96.8% (95% CI: 90.2%, 99.2%) for abdominal regional whole-body MRI; sensitivity non-available and 98.3% (95% CI: 95.3, 99.4) for abdominal/pelvic US; and 50.0% (95% CI: 2.7%, 97.3%) and 93.8% (95% CI: 85.6%, 97.7%) for brain MRI. CONCLUSION: Considerations for optimizing imaging protocol, defining criteria for abnormalities, developing a structured reporting system, and practicing consensus double-reading may enhance the diagnostic accuracy for tumor surveillance.

Subacute sclerosing panencephalitis resembling Rasmussen's encephalitis on magnetic resonance imaging.

Subacute sclerosing panencephalitis (SSPE) is a rare, slowly progressing but invariably fatal disease that is related to a prior measles virus infection and most commonly affects paediatric patients. Magnetic resonance (MR) imaging is the modality of choice for determining such changes in white matter. SSPE typically demonstrates bilateral but asymmetric periventricular and subcortical white matter involvement. We herein report a rare case of unilateral white matter involvement in a 13-year-old boy with SSPE that closely simulated Rasmussen's encephalitis. To the best of our knowledge, this is the first report of an atypical presentation on MR imaging in which SSPE was a rare cause of unilateral brain parenchymal involvement in a patient with intractable seizures.

MRI findings in acute hyperammonemic encephalopathy resulting from decompensated chronic liver disease.

Hyperammonemic encephalopathy is a type of metabolic encephalopathy with diversified etiology. Hyperammonemia is the end result of several metabolic disorders such as congenital deficiencies of urea cycle enzymes, hepatic encephalopathy, Reye's syndrome and other toxic encephalopathies. Non-specific clinical presentation poses a great challenge in early diagnosis of this entity. Irrespective of the underlying etiology, hyperammonemia causes a distinctive pattern of brain parenchymal injury. The cingulate gyrus and insular cortex are more vulnerable to this type of toxic insult. Characteristic magnetic resonance imaging findings in combination with laboratory parameters can help to differentiate this entity from other metabolic encephalopathy and thus aiding in early diagnosis and treatment.

Congenital distal tibiofibular synostosis.

Congenital distal tibiofibular synostosis is a very rare anomaly. The cases of congenital tibiofibular synostosis reported in the literature so far have been confined to the proximal tibiofibular joint. We present an unusual case of tibiofibular synostosis that involves the distal part of the tibia and fibula based on characteristic X-ray, CT, and MRI findings.

Idiopathic chondrolysis of hip.

An uncommon case of idiopathic chondrolysis of the hip in an 11-year-old girl is reported. It was characterized by clinical presentation, laboratory tests, and imaging techniques. A differential diagnosis is discussed highlighting the radiological features for quick diagnosis.