Clinical and imaging features in fibro-adipose vascular anomaly (FAVA)

Fibro-Adipose Vascular Anomaly of the Lower Extremity

Fibro-adipose vascular anomaly (FAVA) is characterized by intramuscular vascular malformation with secondary overgrowth of further mesenchymal elements, particularly fibro-adipose tissue. A rare disease complicated by nonspecific, overlapping clinical and imaging features, FAVA is often misdiagnosed, causing a dilemma in its diagnostic and therapeutical management. We present a case of FAVA of the lower extremity.

Progress about the fibro-adipose vascular anomaly: A review

Fibro-adipose vascular anomaly (FAVA) is a rare and complex vascular malformation associated with persistent pain, limb contracture, and even restriction of activity. However, the pathophysiology of FAVA remains unclear. Although FAVA is a benign vascular malformation, it is highly misdiagnosed and often thus undergoing repeated surgical resection and interventional sclerotherapy, resulting in worsening of symptoms and irreversible dysfunction. Therefore, aggressive diagnosis and treatment are essential. There are several different treatment options for FAVA, including surgical resection, sclerotherapy, cryoablation, drug therapy, and physical therapy. This article reviews the clinical manifestations, pathological features, pathogenesis, and treatment methods of FAVA.

Fat-Containing Soft Tissue Tumors in Children, Adolescents, and Young Adults: Which Require Biopsy?

PURPOSE

To confirm the overall benignity of fat-containing soft tissue tumors (STT) on a pediatric cohort and to define the clinical and imaging features that warrant a biopsy.

METHODS

A retrospective monocentric study was conducted on patients aged less than 25 years consecutively referred for fat-containing STT to our Comprehensive Cancer Center between 1998 and 2022. Tumor imaging characteristics at diagnosis (US, CT, or MRI) were correlated with pathology.

RESULTS

The database extraction identified 63 fat-containing tumors with clinical, histologic, and imaging data available for review. In total, 58 (92%) were benign tumors: 36 lipoblastomas and lipomas, 12 fibrous hamartomas of infancy (FHI), 5 lipofibromatosis, 2 lipomas arborescens, 2 lipomatosis and 1 spindle-cell lipoma. Five patients (8%) were diagnosed with liposarcoma. Factors significantly correlated with malignancy were age >10 years old (p < 0.001), having a cancer-predisposing condition (p < 0.001), a percentage of fat <25% (p = 0.002), and a presence of myxoid zones (p < 0.001) on imaging.

CONCLUSION

Most fat-containing STT in children may be classified as benign tumors based on clinics and imaging. The indication for biopsy could be limited to patients aged 10 years or more with either a cancer-predisposing condition or imaging features demonstrating either a low-fat component (<25%) or the presence of myxoid zones.

Radiomics-based machine learning approach in differentiating fibro-adipose vascular anomaly from venous malformation

BACKGROUND

As a complex vascular malformation, fibro-adipose vascular anomaly was first proposed in 2014. Its overlap with other vascular malformations regarding imaging and clinical features often leads to misdiagnosis and improper management.

OBJECTIVE

To construct a radiomics-based machine learning model to help radiologists differentiate fibro-adipose vascular anomaly from common venous malformations.

MATERIALS AND METHODS

We retrospectively analyzed 178 children, adolescents and young adults with vascular malformations (41 fibro-adipose vascular anomaly and 137 common vascular malformation cases) who underwent MRI before surgery between May 2012 to January 2021. We extracted radiomics features from T1-weighted images and fat-saturated (FS) T2-weighted images and further selected features through least absolute shrinkage and selection operator (LASSO) and Boruta methods. We established eight weighted logistic regression classification models based on various combinations of feature-selection strategies (LASSO or Boruta) and sequence types (single- or multi-sequence). Finally, we evaluated the performance of each model by the mean area under the receiver operating characteristics curve (ROC-AUC), sensitivity and specificity in 10 runs of repeated k-fold (k = 10) cross-validation.

RESULTS

Two multi-sequence models based on axial FS T2-W, coronal FS T2-W and axial T1-W images showed promising performance. The LASSO-based multi-sequence model achieved an AUC of 97%±3.8, a sensitivity of 94%±12.4 and a specificity of 89%±9.0. The Boruta-based multi-sequence model achieved an AUC of 97%±3.7, a sensitivity of 95%±10.5 and a specificity of 87%±9.0.

CONCLUSION

The radiomics-based machine learning model can provide a promising tool to help distinguish fibro-adipose vascular anomaly from common venous malformations.

Successful treatment of fibro-adipose Vascular Anomaly with sirolimus

BACKGROUND

The purpose of this study was to present our initial experience in using sirolimus therapy to treat fibro-adipose vascular anomaly (FAVA).

METHODS

We retrospectively reviewed the medical records of eight patients with FAVA who were treated with sirolimus at our hospital between July 2017 and October 2020.

RESULTS

Six girls (75%) and two boys (25%) were included in the cohort; the average age was 8 years (range, 1-13 years). Vascular tumors developed mainly on the extremities, including the forearm (n = 2; 25.0%), calf (n = 4; 50.0%), and thigh (n = 2; 25.0%). The predominant symptoms included swelling of the lesion (n = 8; 100%), pain (n = 7; 87.5%), contracture (n = 3; 37.5%), and phlebectasia (n = 3; 37.5%). Magnetic resonance imaging was the primary method used for FAVA diagnosis, and all patients underwent enhanced MRI. All lesions were heterogeneous with hyperintense T1 signals. The fat-suppressed T2-weighted images also revealed heterogeneous hyperintense masses, thus indicating fibrofatty infiltration. All eight patients received a sirolimus treatment regimen after FAVA diagnosis. One patient underwent tumor resection but experienced recurrence, whereas the other six patients underwent biopsy. Histological examination revealed that the lesions consisted of fibrofatty tissue with abnormal venous channels and anomalous lymphatic vascular components. Sirolimus softened the masses and caused tumor shrinkage within 5.25 ± 2.6 weeks (range, 2-10 weeks) after treatment initiation. The tumors also involuted rapidly and became stable within 7.75 ± 2.25 months after treatment initiation (range, 6-12 months). All seven patients experiencing pain reported relief within 3.8 ± 1.8 weeks (range, 2-7 weeks) after initiation of sirolimus therapy. Sirolimus alleviated but did not fully resolve the contracture in three patients. Remarkably, five patients exhibited a complete response, and three patients exhibited a partial response. At the time of the last follow-up, three patients had begun to gradually taper off sirolimus after 24 months of treatment and maintained a low blood sirolimus concentration. No serious adverse effects were observed during treatment.

CONCLUSION

FAVA is a complex vascular malformation that appears to respond well to sirolimus treatment. Thus, sirolimus may be an effective and safe treatment for FAVA.

LEVEL OF EVIDENCE

LEVEL IV.

Fibro-Adipose Vascular Anomaly: Characteristic Imaging Features on Sonography and Magnetic Resonance Imaging

OBJECTIVE

To analyse the image characteristics of fibro-adipose vascular anomaly (FAVA) and the value of ultrasound and magnetic resonance imaging (MRI) for its diagnosis.

METHODS

The clinical and imaging data characteristics of 10 patients with FAVA admitted to our hospital between January 2018 and December 2020 who underwent ultrasound and MRI diagnosis were retrospectively analysed.

RESULTS

A total of 10 patients (six males and four females) with pathologically confirmed FAVA, aged from 3 to 27 years (median: 13 years), underwent ultrasound and MRI; of these, two patients underwent MRI-enhanced examinations. All lesions involved mainly muscle, with a few disruptions and involvements of subcutaneous fat. Five cases were located subcutaneously near the fascia; one case was adjacent to the periosteum. Ultrasound showed fascial tail in seven cases, and MRI showed fascial tail in six cases. Both ultrasound and MRI showed the lesions to be oval-shaped masses with blurred borders and a mean maximum diameter of 99.8 ± 48.7 mm. Ultrasound showed a mass with a mixture of high and low echoic areas. Magnetic resonance imaging imaging showed a heterogeneous, mixed-signal intensity on T1-weighted images, probably influenced by the fibrous and fatty components of the lesion. T2-weighted images showed a mixed-high signal. Enhanced computed tomography scans showed significant heterogeneous enhancement of the lesions.

CONCLUSION

Both ultrasound and MRI showed that fascial tail sign is an important imaging feature for FAVA disease; this provides a reliable basis for its diagnosis and can be used to distinguish it from venous malformations, which have no fascial tail signs. Therefore, fascial tail signs can be used as imaging features and require special attention in the diagnosis of FAVA disease.

Vascular anomalies: diagnostic features and step-wise approach

The first part of this review article emphasized correct nomenclature, classification systems, and imaging algorithm of vascular anomalies. The second part of the review discusses the individual entities, highlighting the characteristic clinico-radiological features of the commonly encountered ones. A step-wise algorithmic approach is also proposed for the evaluation of a suspected case of vascular anomaly.

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.

Vascular anomalies: clinical perspectives

Vascular anomalies are classified as vascular tumors or vascular malformations according to their cellular features and biological behavior. Detailed history and clinical assessment allow for the proper clinical diagnosis of most vascular anomalies and guide the choice of imaging to evaluate them. This article discusses the general information needed from a clinical history and physical exam to formulate a diagnosis of vascular anomaly. Then, the authors review the clinical findings from the most common vascular tumors and vascular malformations.

PIK3CA mutation correlates with mTOR pathway expression but not clinical and pathological features in Fibfibroipose vascular anomaly (FAVA)

Background

Fibro-adipose vascular anomaly (FAVA) is a rare and new entity of vascular anomaly. Activating mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene were identified at a frequency of 62.5% in FAVA cases. The PIK3CA mutations excessively activate mammalian target of rapamycin (mTOR) pathway, which promotes angiogenesis and lymphangiogenesis, implying that PIK3CA mutations may act as drivers of FAVAs. This study investigated the correlations between PIK3CA mutational status, clinicopathological features and immunohistochemical expression of the mTOR pathway in a series of FAVA.

Methods

We retrospectively evaluated the clinical and pathological findings of four FAVA cases. We performed next-generation sequencing (NGS) with a custom panel of genes associated with the mTOR pathway and genes responsible for other vascular anomalies; followed by direct sequencing and immunohistochemical analysis of the mTOR pathway.

Results

Two PIK3CA-mutation cases and two PIK3CA-wild-type (wt) cases exhibited similar typical clinical features of FAVA. Histological analysis revealed venous malformation, lymphatic malformation, nerves containing enlarged abnormal vessels and fibrofatty tissue were observed regardless of PIK3CA mutational status. In contrast to clinical and histological findings, the immunohistochemical expression of activated AKT and mTOR that are upstream of the mTOR pathway was detected in abnormal vessels of PIK3CA-mutation cases but not in those of PIK3CA-wt cases. However, activated eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and ribosomal protein S6 kinase 1 (S6K1), both of which are downstream effectors of the mTOR pathway, were expressed in abnormal vessels of both PIK3CA-mutation and PIK3CA-wt cases. Furthermore, targeting NGS did not find any common genetic mutations involved in the mTOR pathway among PIK3CA-wt cases.

Conclusions

There was no significant association between the presence of PIK3CA mutations and the clinicopathological features of FAVA, suggesting that the PIK3CA gene is not necessarily involved in the onset of FAVA. FAVAs lacking PIK3CA mutations may be caused by other gene mutations that activate 4EBP1 and S6K1.

Fibro Adipose Vascular Anomaly: A Rare and Often Misdiagnosed Entity

Fibro adipose vascular anomaly (FAVA) is a rare type of vascular malformation with distinct clinical features. The authors here discussed the clinical, imaging, differential diagnosis, histopathological features, and treatment options of FAVA along with an illustrative case. It is important to know about this uncommon entity as this can be misdiagnosed due to the overlapping clinical features with other common entities. It is a benign condition with no proven malignant potential. There are no guidelines regarding the best treatment option.

A Step-by-Step Sonographic Approach to Vascular Anomalies in the Pediatric Population: A Pictorial Essay

Vascular anomalies are a common cause of soft-tissue masses in children and often referred for ultrasonographic (USG) evaluation. They are broadly classified as vascular tumors (hemangiomas, hemangioendotheliomas, and angiosarcomas) or vascular malformations (venous malformations, lymphatic malformations, and arteriovenous malformations). Findings on USG and Doppler imaging can be used to categorize vascular anomalies into high- or low-flow lesions, which forms the basis for further workup, diagnosis, and management. On careful evaluation of various sonographic features, in conjunction with clinical findings, an accurate clinicoradiological diagnosis can be made in most cases. Further imaging with magnetic resonance (MR) imaging or computed tomography (CT) helps in delineation of lesion extent, whereas MR or CT angiography is useful to map the vascular supply of high-flow lesions. We have illustrated and discussed a step-by-step approach to diagnose vascular anomalies using ultrasound and Doppler imaging.

Lower Extremity Fibro-Adipose Vascular Anomaly-Case Report

Fibro-adipose vascular anomaly (FAVA) is a painful complex vascular malformation, characterized by muscle fibrofatty infiltration, usually in lower limb, associated with contracture of the ipsilateral extremity. This article describes the first case of FAVA reported in Portugal successfully treated with surgery. A 9-year-old female was admitted complaining of a painful mass in the right leg. The MRI scan showed the presence of a 5 × 4 × 4 cm mass in the right leg consistent with FAVA located in the peroneus longus muscle. The patient underwent resection of the involved muscle. She had 6 months of follow-up without any relevant clinical event. The authors also highlight the difference between FAVA and venous malformation. Early surgery is a treatment option that can prevent long-term consequences, as contracture and movement limitation.