Lipoblastoma: MRI appearances of a rare paediatric soft tissue tumour

Rapidly growing intramuscular lipoma: a unique entity of benign lipomas in children

This report presents a case of an intramuscular lipoma observed in the left back of a healthy female toddler. It was resected after 3 months of observation because of rapid enlargement, raising suspicion of malignancy. Histopathological examination confirmed a diagnosis of intramuscular lipoma without malignant and blastemal components. Intramuscular lipomas are benign neoplasms that mostly appear as a rapidly growing tumour. Several hypotheses regarding the pathogenesis of this characteristic growth pattern have been proposed, including atrophy of the surrounding muscle, reactive adipocytic neoformation and multiple contractive interactions between the lipoma and the surrounding muscle.

Update of Pediatric Lipomatous Lesions: A Clinicopathological, Immunohistochemical and Molecular Overview

Lipomatous neoplasms are a rare entity in the pediatric population, comprising less than 10% of soft tissue tumors in the first two decades of life. Some characteristics of pediatric adipocytic tumors are analogous to their adult counterparts, some pediatric lipomatous lesions however harbor unique features. In recent years, there have been significant advances in the understanding of the pathogenesis and hence in the classification and treatment of pediatric adipocytic tumors. This literature-based article will provide a review of the presently known clinicopathological, immunohistochemical and molecular features of pediatric lipomatous lesions.

Imaging features of Lipoblastoma

Lipoblastoma is a rare benign soft tissue tumor found in infants and young children. It presents as an enlarging mass commonly observed in extremities, trunk, head and neck regions. Imaging features include a hyper-echoic mass on ultrasound, heterogonous fat density lesion on CT scan with enhancing septations and no calcification, and high T1 signal mass that drops the signal intensity on fat suppression MRI images. Total excision of such lesion is the treatment of choice, and follow-up is recommended to rule out recurrence.

Lipoblastoma: computed tomographic and magnetic resonance imaging features correlate with tumor behavior and pathology

BACKGROUND

Lipoblastoma is a rare benign neoplasm of immature fat cells in children. Imaging appearances are frequently complex, sometimes simulating liposarcoma.

OBJECTIVE

To characterize features of lipoblastoma on MRI and CT in comparison with recurrence risk.

MATERIALS AND METHODS

We identified cases via retrospective review of histopathology-proven lipoblastoma cases in a large referral database and a pediatric medical center. Two radiologists scored CT and MRI on the basis of lesion features.

RESULTS

We included a total of 56 children (32 boys and 24 girls) with a mean age of 2.6 years (range 0.1-13 years). Extremity lesions were most common (27%), followed by neck (19%), gluteal region (18%), chest (14%) and mesentery (14%). Children most commonly presented with painless masses (73%), followed by dyspnea (9%), distension (9%) and pain (7%). Non-adipose soft-tissue components were identified on CT and MRI in 78% of cases. Significant (moderate or marked) septations were noted in 59% and enhancement in 35%. Compartmental invasion was present in 43% of cases. Of paraspinal cases, 38% involved the neural foramina or central canal. Lesion complexity did not significantly correlate with age. Recurrence was observed in 9% of cases and was significantly correlated with compartmental invasion (correlation: 0.303, P=0.009) and septation complexity (correlation: 0.227, P=0.038) on initial imaging.

CONCLUSION

Although lipoblastoma is a fat-containing entity, many lesions demonstrate marked complexity and local infiltration that resemble liposarcoma, which is exceedingly rare in younger children. Compartmental invasion and thicker septations appear to confer greater risk of recurrence following resection.

Follow-up outcomes of pediatric patients who underwent surgical resection for lipoblastomas or lipoblastomatosis: a single-institution experience with a systematic review and meta-analysis

PURPOSE

The objective of this study was to examine the long-term outcomes of pediatric patients who underwent surgical resection for lipoblastoma and lipoblastomatosis (LB/LBM).

METHODS

A single-center retrospective study of pediatric patients with LB/LBMs seen between 1991 and 2015 was conducted. A systematic review, including studies published prior to late August 2018, was performed. Using a random effect meta-analysis, pooled weighted proportions and unadjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

The retrospective study included 16 patients, while the systematic review included 19 published studies consisting of 381 patients. Among 329 (82%) patients with follow-up information, the pooled recurrence rate was 16.8% (95% CI 10.9-23.5%; I² = 59%). The reported time to recurrence ranged from < 1 to 8 years. Recurrence risk was greater for incomplete (n = 34) than complete resection (n = 150): OR 11.4 (95% CI 3.0-43.6; I² = 43%). LBMs (n = 35) had a greater recurrence risk than LBs (n = 116): OR 5.5 (95% CI 1.9-15.9; I² = 0%). Recurrences were higher for studies with approximately ≥ 3 years of follow-up versus studies with < 3 years of follow-up.

CONCLUSION

Recurrences are more likely to occur with LBMs and/or incomplete resection. Follow-up beyond 3-5 years should be considered given that the recurrence risk appears to be greater in the long-term.

Up-To-Date Practical Imaging Evaluation of Neonatal Soft-Tissue Tumors: What Radiologists Need to Know

OBJECTIVE

The purposes of this article are to provide an up-to-date overview of neonatal soft-tissue tumors, including information regarding their unique nature, and to present practical imaging techniques and characteristic imaging findings.

CONCLUSION

Neonatal soft-tissue tumors are a unique set of neoplasms that often have characteristic clinical and imaging findings. Imaging evaluation, mainly with ultrasound and MRI, plays an important role in the initial diagnosis, staging, preoperative assessment, and follow-up evaluation. Clear understanding of practical imaging techniques combined with up-to-date knowledge of characteristic imaging findings can help the radiologist provide a timely and accurate diagnosis of these neoplasms and can lead to optimal neonatal patient care.

Lipofibromatosis: magnetic resonance imaging features and pathological correlation in three cases

Lipofibromatosis is a rare, benign, but infiltrative, soft tissue tumor seen in children. We present three cases of lipofibromatosis, each with different magnetic resonance imaging features and correlate this with the histological findings. The patients comprised two males and one female who presented in infancy; at birth, 5 months, and 7 months of age. Clinically, the masses were painless and slow-growing. The masses ranged in size from 2 to 6 cm and involved the distal extremities in two cases (one foot, one wrist) and the trunk. Magnetic resonance imaging showed lipomatous lesions with varying amounts of adipose and solid components in each case. There were no capsules at the periphery of the lesions. One case showed a fat-predominant lesion, another an equal mixture of fat and solid tissue, and the third was predominantly solid. This was reflected in the histology, which showed corresponding features. Radiological and histopathological differential diagnoses are reviewed.

Recurrent lipoblastoma of upper extremity in a 9-year-old boy

Lipoblastoma is a benign soft-tissue tumour of infancy and early childhood. The location of the tumour varies from that of the extremities, trunk, retroperitoneum, mediastinal, inguinal and scrotal regions. The most common symptoms are painless mass with or without increasing size. Complete surgical excision is the gold standard for managing this entity. Though rare, the recurrence occurs usually because of incomplete excision. We report a case of recurrent lipoblastoma of the upper extremity in a 9-year-old boy.

Mesenteric lipoblastoma presenting as a small intestinal volvulus in an infant: A case report and literature review

A 1-year-old boy with no underlying disorder presented with non-bilious vomiting since 4 days before admission. He was referred to our hospital and was diagnosed with a small bowel obstruction due to an intraabdominal tumor. Laparotomy revealed an intestinal volvulus with a soft and lobulated tumor arising from the mesentery. The resected tumor with a small part of the small bowel was diagnosed as lipoblastoma histologically. From a literature review, mesenteric lipoblastoma with an intestinal volvulus showed different characteristics such as greater frequency of vomiting and less frequency of abdominal mass as clinical symptoms, and the size of the tumor was smaller than that of the tumor without the intestinal volvulus.

Parotid lipoblastoma in a child: Rare presentation as huge infratemporal mass with cervical extension

Lipoblastomas arising within the parotid gland and extending into the infratemporal fossa are very rare. They are common in children <3 years of age. Access to the tumour requires careful planning and interpretation of imaging studies. Lipoblastomas tend to recur. Meticulous dissection of the tumour is needed to prevent recurrence. By adopting the appropriate approach, complete removal is possible with minimal morbidity.

Soft-tissue masses and masslike conditions: what does CT add to diagnosis and management?

OBJECTIVE

Although MRI is the technique of choice for evaluating most soft-tissue masses, CT often provides valuable complementary information. Specifically, there are distinguishing CT characteristics that can suggest a specific diagnosis, including the lesion's mineralization pattern, density, pattern of adjacent bone involvement, and degree and pattern of vascularity.

CONCLUSION

This article provides an overview of the CT evaluation of soft-tissue masses, emphasizing a differential diagnosis based on these CT features.

Soft tissue tumours: imaging strategy

Vascular tumours and malformations, fibrous and fibrohistiocytic tumours and pseudotumours are the most common benign soft-tissue masses observed in children, and can be treated conservatively. Rhabdomyosarcomas are the most frequent malignant tumours, accounting for about half of soft tissue sarcomas. A child referred for a soft-tissue mass should ideally be managed by a multidisciplinary team and primary excision should be proscribed until a definite diagnosis has been established. Clinical examination, conventional radiography and US with Doppler represent the first-line examinations and are sometimes sufficient to make a diagnosis. In all other situations, MRI is mandatory to establish the aggressiveness and extension of the tumour. This technique provides the relevant data to guide the decision regarding tissue sampling.

Giant mesenteric lipoblastoma in a 4-year-old child

Lipoblastoma is a rare benign neoplasm of embryonal fat that occurs typically in infancy and childhood. An unusual case of a giant mesenteric lipoblastoma in a 4-year-old child is presented. The lipoblastoma was completely removed. Histopathologic examination confirmed the diagnosis of mesenteric lipoblastoma. Observation of the patient for 4 months postoperatively showed no evidence of recurrence.

Soft tissue tumors: grading, staging, and tissue-specific diagnosis

The value of medical imaging in detection, staging, grading, and tissue-specific diagnosis has been substantially increased, especially after the introduction of magnetic resonance imaging, the combined use of cytogenetic and molecular techniques and the refinement of biopsy techniques. In this paper, we will focus on the combination of parameters including clinical information, prevalence, age, location, and findings on medical imaging, yielding the highest diagnostic sensitivity and specificity. An imaging prototype of a malignant soft tissue tumor will be proposed. In a second part, we will present an overview of most common soft tissue tumors, especially focusing on these tumors having more characteristic imaging features that allow to make a more detailed tissue-specific diagnosis. Finally, we will give the radiologist a short list of important things to take home.

Cervical lipoblastoma: Case report, review of literature, and genetic analysis

BACKGROUND

Lipoblastoma is a rare, benign tumor of infants and children, usually occurring in the extremities and trunk, with only a few cases reported in the neck.

METHODS

We describe the case of an infant with a rapidly enlarging, painless neck mass. MRI revealed a 4-cm-diameter mass deep to the paraspinal muscles, in close proximity to the C2 vertebral foramen. Review of literature, diagnostic methods, and genetics of lipomatous tumors are discussed.

RESULTS

Complete surgical excision via a posterior cervical approach demonstrated irregular lobules of immature fat cells separated by a loose, myxoid connective tissue. Histology and genetic analysis confirmed the diagnosis of lipoblastoma.

CONCLUSION

Cervical lipoblastoma is rare, and typically presents as an asymptomatic, painless mass, rarely causing airway obstruction or nerve compression. MRI can be helpful in identifying the lipomatous nature of the mass, but the findings can be inconsistent due to variable maturity of fat cells and the mesenchymal content of the tumor. Chromosomal analysis is useful in differentiating lipoblastoma from liposarcoma. Recommended treatment is complete surgical excision.

Giant omental lipoblastoma in a 10-month-old infant composing 20% of total body weight

Lipoblastoma of the greater omentum is an extremely rare benign tumor with less than 10 cases reported in the available literature. We report an unusual case of a 10-month-old girl with a giant omental lipoblastoma that composed 20% of her total body weight (1480 g, 17 x 12 x 16 cm). Complete excision of the tumor was performed. Histology confirmed the diagnosis of omental lipoblastoma.

[Intrathoracic lipoblastoma with costal involvement]

We report the case of a two-year-old girl with a lipoblastoma arising from the chest wall with intrathoracic extension and costal involvement. The diagnosis was confirmed histologically after surgery. Plain-film chest x-rays showed an extrapleural mass; computed tomography (CT) and magnetic resonance imaging (MRI) suggested fatty contents. The differential diagnosis is mainly versus liposarcoma, which is extremely rare in children.

Lipoblastoma and lipoblastomatosis

We report two cases of lipoblastoma of the buttock in a 10-month-old boy and a 20-month-old girl, the first with rearrangement of chromosome 8 and the second without cytogenetic abnormality, and one case of lipoblastomatosis of a leg in a 6-month-old boy with a normal karyotype but with a rearrangement of the PLAG1 gene. Lipoblastoma and lipoblastomatosis are two different presentation of the same rare benign soft tissue mesenchymal tumour arising from fetal white fat and occurring almost exclusively in young children under 3 years. These neoplasms have no malignant potential but may recur in cases of incomplete resection. Histological diagnosis sometimes used to be difficult because of the close resemblance of the lesion with myxoïd liposarcoma. Nowadays, cytogenetic analysis may contribute to the diagnosis by showing abnormalities of the long arm of chromosome 8, leading to rearrangement of the PLAG1 gene. Actual advances in cytogenetic molecular analysis may aid in accurate diagnosis.

Radiological-pathological correlation in lipoblastoma and lipoblastomatosis

BACKGROUND

Lipoblastoma and lipoblastomatosis are uncommon benign mesenchymal lesions that predominantly occur in infancy and early childhood.

OBJECTIVE

To evaluate the imaging and histological features of lipoblastoma and lipoblastomatosis.

MATERIALS AND METHODS

Retrospective review of the radiological and pathological findings in children with lipoblastoma and lipoblastomatosis treated at a single centre between 1997 and 2004.

RESULTS

Eight children (median age 18 months) had undergone imaging and surgery at our institution. An infiltrative growth pattern was identified at imaging in two children with lipoblastomatosis, and a well-defined mass in six children with lipoblastoma. In all patients, imaging showed a lesion composed mostly, but not entirely, of fat. There were no recurrences at follow-up of between 1 and 91 months.

CONCLUSION

In infancy and early childhood, the identification of a tumour composed mostly of fat should suggest the diagnosis of lipoblastoma or lipoblastomatosis.

Magnetic Resonance Imaging in Lipoblastoma: Can it be a Diagnostic Modality?

Magnetic resonance imaging (MRI) is generally an efficient tool for establishing the differential diagnosis of soft tissue tumours. We simultaneously encountered two patients with adipose tumours in the neck. Both had similar clinical features and MRI findings: lobular high intensity tumours on both T1-and T2-weighted images equivalent to subcutaneous fat with septal formation. The provisional diagnosis in both cases was lipoblastoma and both had complete excisions. Histopathological diagnoses, however, were different (lipoblastoma and fibrolipoma), indicating that while MRI is excellent for demonstrating the anatomical detail of soft tissue masses, it is not specific enough to be used alone for differentiating between adipose tumours. In this report, we assess the value of MRI and recommend a more appropriate and patient-friendly protocol for the evaluation for adipose tumours in children.

Imaging and diagnostic strategy of soft tissue tumors in children

The diagnosis of a soft tissue mass in children is a common clinical situation. Most of the lesions are benign and can be treated conservatively or by non-mutilating surgery. Nevertheless, the possibility of a malignant soft tissue tumor must be systematically considered. The most frequent benign soft tissue lesions in children are vascular lesions, fibrous and fibrohistiocytic tumors and pseudotumors, whereas rhabdomyosarcomas account for 50% of all soft tissue sarcomas. A child presenting an atypical soft tissue mass should be managed by a multidisciplinary centre, and primary resection must be proscribed until a definite diagnosis has been established. The role of imaging is essential either to confirm the benign nature of the mass or to give arguments to perform a diagnostic biopsy. Clinical examination, conventional radiography and ultrasound with Doppler represent the first-line examinations and are sometimes sufficient to assess a diagnosis. In all other situations, MRI is mandatory to establish the probable nature of the lesion and to assess local extension.

Lipoblastome omental

Lipoblastoma is a rare benign neoplasm of foetal fat tissue. To our knowledge, less than ten cases of omental lipoblastoma have been reported in the literature. We present a new case of omental lipoblastoma in a 3-month old girl. The role of CT in the diagnosis and surgery planning of this tumor will be discussed.

Aspect inhabituel d’un lipoblastome axillaire chez un nourrisson

Lipoblastoma is an uncommon benign soft tissue tumor of infancy and early childhood with a predilection for the extremities. CT and MRI can confirm the presence of fat components in the tumor. In addition, MRI better shows the anatomical extent. By showing lipoblastoma proliferation, histology confirms the diagnosis. Gross total excision is the treatment of choice. The authors report a case of unusual lipoblastoma of the axillary region, composed of fatty components with multiple cystic areas presenting at birth, with recurrence 9 months after excision.

From the archives of the AFIP: benign musculoskeletal lipomatous lesions

Benign lipomatous lesions involving soft tissue are common musculoskeletal masses that are classified into nine distinct diagnoses: lipoma, lipomatosis, lipomatosis of nerve, lipoblastoma or lipoblastomatosis, angiolipoma, myolipoma of soft tissue, chondroid lipoma, spindle cell lipoma and pleomorphic lipoma, and hibernoma. Soft-tissue lipoma accounts for almost 50% of all soft-tissue tumors. Radiologic evaluation is diagnostic in up to 71% of cases. These lesions are identical to subcutaneous fat on computed tomographic (CT) and magnetic resonance (MR) images and may contain thin septa. Lipomatosis represents a diffuse overgrowth of mature fat affecting either subcutaneous tissue, muscle or nerve, and imaging is needed to evaluate lesion extent. Lipoblastoma is a tumor of immature fat occurring in young children, and imaging features may reveal a mixture of fat and nonadipose tissue. Angiolipoma, myolipoma, and chondroid lipoma are rare lipomatous lesions that are infrequently imaged. Spindle cell and pleomorphic lipoma appear as a subcutaneous lipomatous mass in the posterior neck or shoulder, with frequent nonadipose components. Hibernoma appears as a lipomatous mass with serpentine vascular elements. Benign lipomatous lesions affecting bone, joint, or tendon sheath include intraosseous lipoma, parosteal lipoma, liposclerosing myxofibrous tumor, discrete lipoma of joint or tendon sheath, and lipoma arborescens. Intraosseous and parosteal lipoma have a pathognomonic CT or MR appearance, with fat in the marrow space or on the bone surface, respectively. Liposclerosing myxofibrous tumor is a rare intermixed histologic lesion commonly located in the medullary canal of the intertrochanteric femur. Benign lipomatous lesions may occur focally in a joint or tendon sheath or with diffuse villonodular proliferation in the synovium (lipoma arborescens) and are diagnosed based on location and identification of fat. Understanding the spectrum of appearances of the various benign musculoskeletal lipomatous lesions improves radiologic assessment and is vital for optimal patient management.

Lipoblastoma in a four-year-old African child

A four-year old Sudanese child presented with a growing mass in the medial aspect of the right thigh. The mass appeared during the neonatal period. On clinical examination a diagnosis of lipoblastoma was entertained on the basis of the patient's age and the clinical features of the mass. The tumor was completely excised surgically. The clinical diagnosis of lipoblastoma was confirmed pathologically. Follow-up of the patient for 6 months postoperatively showed no evidence of recurrence.

Lipoblastoma of the neck: a case report and literature review

Lipoblastoma is a rare benign tumor arising from embryonic white fat. We describe a case of huge lipoblastoma of the neck in a 1-year-old boy. Magnetic resonance imaging (MRI) revealed a 7 x 7 cm neck mass that extruded into the parapharyngeal and paratracheal spaces. At the operation, a well-circumscribed and extensively growing tumor was completely removed. Histopathologic examination showed that the tumor contained lobulated mature adipose tissue and myxoid tissue with lipoblasts and other immature fat cells. The postoperative course was uneventful, and no recurrence of tumor has been noted in more than 2 years follow-up.

Pediatric soft-tissue tumors

Soft-tissue tumors in children (<18 years) are a heterogeneous group of lesions. Masses may be asymptomatic or associated with pain or discomfort. Although most lesions are benign, developing an appropriate differential diagnosis requires knowledge of the clinical and radiographic characteristics of tumors and tumorlike conditions in children. A thorough history and physical examination, followed by appropriate imaging studies, when indicated, can establish a correct diagnosis and help determine appropriate treatment recommendations.

Magnetic resonance imaging of soft-tissue tumors in children

Magnetic resonance imaging (MRI) has become an important diagnostic tool in the detection and characterization and local anatomic staging of soft-tissue tumors in children. This article outlines some of the procedural issues unique to the pediatric population.

Lipoblastoma: a rare cervical mass in childhood

A 4-year-old girl had a left side cervical swelling for three months. The mass was free from surrounding tissues and excised completely. Histopathologic diagnosis of the specimen was lipoblastoma. Cervical lipoblastoma is a rapidly growing neoplasm. Only two cases of cervical lipoblastomas caused airway obstruction have been reported. Recurrence is rare in cases of lipoblastoma. Complete excision of the tumor is the treatment of choice. Seventeen cases of cervical lipoblastoma have been reported until now in the literature, but we think that lipoblastoma is more frequent than reported. Lipoblastoma must be remembered as a rare cause of cervical masses in childhood.

Lipoblastoma: pathophysiology and surgical management

BACKGROUND/PURPOSE

Lipoblastoma/lipoblastomatosis is a poorly understood and uncommon soft tissue tumor of infancy and early childhood. Twenty-four patients that presented to a single institution over a 15-year period were reviewed for clinical features and outcome.

METHODS

A retrospective review was conducted.

RESULTS

Twenty-five cases were identified; 1 chart was not available for review. Fourteen girls and 11 boys with a median age of 20 months (2 months, 10 years) presented with 26 separate tumors. Nineteen were focal and 7 diffuse. The tumors were located on the trunk (n = 13), leg (n = 6), arm (n = 3), and head and neck (n = 4). Five patients (all with diffuse type) had up to 3 recurrences.

CONCLUSIONS

Patients with focal lipoblastoma are unlikely to require further surgery after initial resection. Patients with diffuse lipoblastoma (lipoblastomatosis) are likely to have recurrent disease (usually within 2 years) and should undergo close follow-up. Genetic analysis of the specimen will help exclude liposarcoma. Recurrent lesions are best imaged with magnetic resonance imaging to assess extent and plan reconstruction if necessary.

MR imaging differentiation of soft-tissue hemangiomas from malignant soft-tissue masses

OBJECTIVE

The purpose of this study was to determine whether MR imaging features can reliably distinguish hemangiomas from malignant soft-tissue masses.

MATERIALS AND METHODS

We retrospectively reviewed MR imaging studies of 22 patients with soft-tissue hemangiomas and 22 patients with malignant soft-tissue masses. Images were reviewed and agreement reached by a consensus interpretation of two observers and by an independent observer. Masses were evaluated for signal intensity on T1- and T2-weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots). Lesion T2 signal and lesion enhancement with gadolinium administration were also objectively measured using regions of interest and comparison with skeletal muscle.

RESULTS

Signal intensity on T1-weighted imaging of hemangiomas and malignant soft-tissue masses was similar. Subjective analysis showed greater T2 signal and gadolinium enhancement in hemangiomas; however, the differences were not statistically significant on objective analysis. Lobulation, septation, and central low-signal-intensity dots were all more common in hemangiomas, with statistical significance achieved; the combination of all three findings was specific for hemangioma.

CONCLUSION

Although no single MR imaging feature was diagnostic in this study, analysis of lesion morphology, signal intensity, and enhancement with gadolinium allowed MR imaging differentiation of hemangiomas from malignant soft-tissue masses.