Ultrasonography and magnetic resonance imaging features of kaposiform hemangioendothelioma and tufted angioma

Radiologic and Clinical Features of Infantile Hemangioma: Potential Pitfalls and Differential Diagnosis

Infantile hemangioma (IH) is the most common neoplasm in children, but it may mimic other types of vascular anomalies or nonvascular benign and malignant tumors. In most cases, the clinical appearance, time of onset, and pattern of involution facilitate its diagnosis. Imaging evaluation is not always needed since the IH features at clinical presentation are usually characteristic, but when needed, US and frequently MRI are the imaging modalities of choice. Clinical photography or photographic documentation plays a central role in monitoring these lesions over their clinical course. Photographic documentation can also add confidence and alert the radiologist when interpreting imaging studies. Some vascular anomalies, especially vascular malformations, are a frequent source of confusion, as these may resemble IHs clinically and at imaging. The lack of uniform terminology also hinders an accurate diagnosis. To unify the terminology and minimize confusion, the International Society for the Study of Vascular Anomalies created a helpful classification in 1994. In addition, radiologists need to be aware of and become familiar with other neoplasms in children that may resemble IH to avoid misdiagnosis and unnecessary procedures. Fibrous and lipomatous tumors are examples of benign tumors that can mimic IHs clinically and at imaging, whereas rhabdomyosarcoma, infantile fibrosarcoma, neuroblastoma, and lymphoproliferative disorders are examples of malignant neoplasms. The authors review the features of IH at clinical presentation and imaging evaluation, highlighting its different phases of evolution and stressing the importance of photographic documentation. The authors also review pitfalls of IH with helpful pearls for differentiation. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Khanna and Briones in this issue.

Current concepts of vascular anomalies

Vascular anomalies encompass a variety of malformations and tumors that can result in severe morbidity and mortality in both adults and children. Advances have been made in the classification and diagnosis of these anomalies, with the International Society for the Study of Vascular Anomalies establishing a widely recognized classification system. In recent years, notable progress has been made in genetic testing and imaging techniques, enhancing our ability to diagnose these conditions. The increasing sophistication of genetic testing has facilitated the identification of specific genetic mutations that help treatment decisions. Furthermore, imaging techniques such as magnetic resonance imaging and computed tomography have greatly improved our capacity to visualize and detect vascular abnormalities, enabling more accurate diagnoses. When considering reconstructive surgery for facial vascular anomalies, it is important to consider both functional and cosmetic results of the procedure. Therefore, a comprehensive multidisciplinary approach involving specialists from dermatology, radiology, and genetics is often required to ensure effective management of these conditions. Overall, the treatment approach for facial vascular anomalies depends on the type, size, location, and severity of the anomaly. A thorough evaluation by a team of specialists can determine the most appropriate and effective treatment plan.

Clinical and imaging features of Kaposiform hemangioendothelioma in infants

Objective

Kaposiform hemangioendothelioma (KHE) is a locally aggressive tumor of vascular origin. This study investigated the clinical and imaging features of KHE to provide a reference for its early diagnosis.

Methods

The clinical and imaging findings of 27 clinically confirmed KHE cases (including 21 with focal lesions and 6 with diffuse lesions) between January 2016 and December 2021 were retrospectively analyzed.

Results

The mean age of the 27 patients was 105 ± 80.27 days. Twenty-two (81.5%) of these patients had Kasabach-Merritt phenomenon. Most KHEs were located in the trunk and/or extremities (22/27). Ultrasonography showed heterogeneous echogenicity and/or striated hypoechoic bands with abundant or patchy blood flow within the tumor. On plain computed tomography (CT), they appeared as heterogeneous lesions isodense with the muscles, with a CT value of 29.58 ± 11.53 HU. In the arterial phase, the KHEs showed striated or lamellar heterogeneous enhancement, with a CT value of 153.91 ± 52.11 HU after enhancement. All KHEs showed uneven and high signal intensity on T2-weighted imaging, mixed high and low signal intensity on fat-saturated images, and no significant diffusion restriction on diffusion-weighted imaging.

Conclusion

KHEs can occur in various locations and present as highly infiltrative and heterogeneous masses that can invade the skin, adjacent muscles, and bones. A vascularized mass with purpuric skin changes, with uneven and high T2WI signal is highly suggestive of the diagnosis of KHE.

MRI-based radiomics in distinguishing Kaposiform hemangioendothelioma (KHE) and fibro-adipose vascular anomaly (FAVA) in extremities: A preliminary retrospective study

OBJECTIVE

To investigate the pretreatment differentiation between Kaposiform hemangioendothelioma (KHE) and fibro-adipose vascular anomaly (FAVA) in extremities of pediatric patients. To build and validate an MRI-based radiomic model.

METHOD

In this retrospective study, we obtained imaging data from 43 patients. We collected and compared clinical information, sketched region of interest (ROI), and extracted radiomic features from fat-suppressed T2-weighted (T2FS) images of the two cohorts of 30 and 13 patients respectively (training versus testing cohort 7:3). To select features, we used two sample t-test and the least absolute shrinkage and selection operator (LASSO) regression. The support vector machine (SVM) classification was constructed and evaluated by receiver operating characteristic (ROC) analysis.

RESULTS

Thirty patients with KHE and 13 patients with FAVA in the extremities were included. Most lesions demonstrated low to intermediate signal intensity on T1-weighted images and hyperintense signals on T2-weighted ones. They also showed similar traits pathologically. Initially, 107 radiomic features were acquired and then three were finally selected. The support vector machine (SVM) model was able to differentiate the two anomalies from each other with an area under the curve (AUC) of 0.807 (95%CI 0.602-1.000) and 0.846 (95%CI 0.659-1.000) in training and testing cohort, respectively.

CONCLUSION

The derived radiomic features were helpful in differentiating KHE from FAVA. A model which contained these features might further improve the performance and hopefully could serve as a potential tool for identification.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 2: vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5^th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous organ soft tissues, as well as the peripheral and autonomic nervous system.

Case report: Kaposi hemangioendothelioma of the right upper limb with the Kasabach-Merritt phenomenon: A potentially lethal diagnostic challenge

Kaposi hemangioendothelioma (KHE) is a rare vascular neoplasm that presents usually within the first year of life. Because of its rarity and complexity, there is often a delay in diagnosis. KHE could be associated with a life-threatening consumptive coagulopathy named the Kasabach-Merritt phenomenon (KMP). Here, we present the case of a 2-month-old girl who presented with progressive redness and swelling of her right upper limb over 6 weeks. Multiple health practitioners misdiagnosed her condition as an insect bite, cellulitis, and necrotizing fasciitis and gave treatment accordingly, which proved futile. A full blood count revealed bicytopenia of anemia and thrombocytopenia, a normal coagulation cascade, low fibrinogen, and raised D-Dimer levels. The imaging was suggestive of a high-flow vascular tumor likely to be a KHE. Subsequently, she was started on single-agent oral sirolimus with a dose increment to achieve satisfactory therapeutic levels and was treated for 1 year. She successfully completed the treatment regimen and had only transient hypertriglyceridemia, which resolved upon the completion of treatment. Currently, she is in remission 3 years after treatment. Keeping her case as an example, we would like to highlight the potentially lethal misdiagnosis of KHE with KMP, the importance of an early diagnosis of this condition, and the successful treatment outcome with single-agent sirolimus.

MR Imaging of Vascular Malformations and Tumors of Head and Neck

Soft tissue vascular anomalies show a wide heterogeneity of clinical manifestations and imaging features. MR imaging has an important role in the diagnosis and management of vascular lesions of the head and neck. MR angiography is mandatory in cases of arteriovenous and combined malformations to assess the high-flow nature/component of the lesions and plan therapy. Infantile hemangiomas can be differentiated from congenital hemangiomas by clinical course. Reactive vascular tumors have nonspecific features similar to infantile hemangiomas. Locally malignant and malignant vascular tumors have irregular borders, infiltration of different tissue planes, and lower apparent diffusion coefficient values than benign vascular tumors.

Mediastinal Masses in Children: Radiologic-Pathologic Correlation

Most pediatric masses in the chest are located in the mediastinum. These masses are often initially detected incidentally on chest radiographs in asymptomatic children, although some patients may present with respiratory symptoms. At chest radiography, the mediastinum has been anatomically divided into anterior, middle, and posterior compartments. However, with the International Thymic Malignancy Interest Group classification scheme, which is based on cross-sectional imaging findings, the mediastinum is divided into prevascular, visceral, and paravertebral compartments. In the prevascular compartment, tumors of thymic origin, lymphomas, germ cell tumors, and vascular tumors are encountered. In the visceral compartment, lymphadenopathy and masses related to the foregut are seen. In the paravertebral compartment, neurogenic tumors are most common. Using the anatomic location in combination with knowledge of the imaging and pathologic features of pediatric mediastinal masses aids in accurate diagnosis of these masses to guide treatment and management decisions. An invited commentary by Lee and Winant is available online. ^©RSNA, 2021.

Kaposiform hemangioendothelioma: current knowledge and future perspectives

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm with high morbidity and mortality. The initiating mechanism during the pathogenesis of KHE has yet to be discovered. The main pathological features of KHE are abnormal angiogenesis and lymphangiogenesis. KHEs are clinically heterogeneous and may develop into a life-threatening thrombocytopenia and consumptive coagulopathy, known as the Kasabach-Merritt phenomenon (KMP). The heterogeneity and the highly frequent occurrence of disease-related comorbidities make the management of KHE challenging. Currently, there are no medications approved by the FDA for the treatment of KHE. Multiple treatment regimens have been used with varying success, and new clinical trials are in progress. In severe patients, multiple agents with variable adjuvant therapies are given in sequence or in combination. Recent studies have demonstrated a satisfactory efficacy of sirolimus, an inhibitor of mammalian target of rapamycin, in the treatment of KHE. Novel targeted treatments based on a better understanding of the pathogenesis of KHE are needed to maximize patient outcomes and quality of life. This review summarizes the epidemiology, etiology, pathophysiology, clinical features, diagnosis and treatments of KHE. Recent new concepts and future perspectives for KHE will also be discussed.