Chromosomal rearrangements in lipofibromatosis

Lipofibromatosis: Central Nervous System Involvement by a Benign Neoplasm

Background: Lipofibromatosis is a relatively new entity, considered in the differential diagnosis of soft tissue tumors in children, involving mainly the extremities. Most cases can be completely resected without recurrence. Atypical forms have been described and their highly infiltrative capability can lead to severe clinical impairment. Case report: We report an infant with rapidly growing posterior cervicothoracic tumor, extending from the bulbo-medullary junction to T6 vertebra, leading to loss of spontaneous breathing, quadriparesis and devastating long-term consequences. Spinal tomography scan at 35 days suggested myelomeningocele. Prenatal and early postnatal ultrasounds were reviewed and no central nervous system involvement or fusion defects were present. Magnetic resonance at 40 days showed infiltrative mass, later confirmed by pathology as lipofibromatosis. Two resections failed to completely remove the tumor. Discussion: Lipofibromatosis can involve critical structures in the central nervous system and is difficult to treat surgically in those circumstances.

Orbital Lipofibromatosis in a Pediatric Patient

A 10-month-old boy presented with a 3-month history of progressive left lower eyelid swelling. Examination demonstrated left lower eyelid fullness and hyperglobus with a fatty appearing inferior fornix mass. Imaging showed a mass isointense to fat in the left lower eyelid extending posteriorly, surrounding the inferior oblique with complete fatty infiltration, obscuration of the inferior rectus, and adherence to the globe. The patient underwent orbitotomy with biopsy and debulking of the tumor. Surgical pathology showed multiple fragments of adipose tissue with foci of plump and spindle-shaped cells arranged in bundles and fascicles, consistent with lipofibromatosis. This case illustrates a rare presentation of orbital lipofibromatosis in a pediatric patient.

Molecular Alterations in Pediatric Fibroblastic/Myofibroblastic Tumors: An Appraisal of a Next Generation Sequencing Assay in a Retrospective Single Centre Study

BACKGROUND

Pediatric fibroblastic/myofibroblastic tumors (PFMTs) can be challenging to definitively classify. Large case series or diagnostic updates have not been recently published despite identification of molecular alterations that could improve diagnostic accuracy. Our review of the literature found that over two-thirds of the more than 30 types of PFMTs harbor recurrent molecular alterations. We performed an institutional review of PFMTs to highlight limitations of a predominantly morphological classification, and evaluated the utility of a next-generation sequencing assay to aid diagnosis.

METHODS

PFMTs identified over a period of 12 years were reviewed, categorized per the new WHO classification, and tested using the Oncomine Childhood Cancer Research Assay.

RESULTS

Eighty-seven specimens from 58 patients were reviewed; 50 were chosen for molecular analysis, 16 (32%) lacking definitive classification. We identified alterations, some novel, in 33% of assayed cases. Expected alterations were identified for most known diagnoses and mutations were identified in 6 of 16 tumors (38%) that were initially unclassified.

CONCLUSION

We confirmed a significant subset of PFMTs remain difficult to classify using current criteria, and that a combined DNA/RNA assay can identify alterations in many of these cases, improving diagnostic certainty and suggesting a clinical utility for challenging cases.

A Case of Inv(1)(q23q31) TPR-NTRK1 Fusion-Positive Spindle Cell Neoplasm in an Infant-Uncovered by Next-Generation Sequencing: Diagnostic Challenge, Review, and Therapeutic Implications

Lately, NTRK-positive mesenchymal tumors are being increasingly identified, mostly in pediatric patients, in view of associated treatment implications, especially in recurrent and unresectable tumors. A 1-year-old male child presented with a rapidly growing tumor mass in his cervical region of 2 months duration. Radiologic imaging disclosed a tumor measuring 11 cm in size, almost filing his right neck spaces. Review of biopsy sections revealed a cellular tumor comprising spindle cells arranged in sheets and fascicles with interspersed collagenous strands and areas of adipocytic, myxoid, and hyaline degeneration. Immunohistochemically, tumor cells were diffusely positive for CD34 and S100 protein. Subsequently, on testing the tumor for a solid tumor gene panel by next-generation sequencing, it was found to be positive for inv(1)(q23q31) TPR-NTRK1 fusion. Furthermore, tumor cells displayed NTRK1 gene rearrangement by fluorescence in situ hybridization technique. The patient was offered chemotherapy; however, he had a rapid local progression, leading to respiratory obstruction; he then succumbed to the disease. The present case underpins the value of next-generation sequencing as a useful technique for uncovering NTRK-fusion-positive mesenchymal tumors. Review of similar cases, diagnostic challenge, and treatment implications in such cases are discussed.

Lipofibromatosis

Introduction: Lipofibromatosis is a benign pediatric soft tissue tumor arising preferentially in the distal extremities. Histologically, the tumor shows abundant adipose tissue admixed with a spindle cell component, often concentrated in septal and perimysial locations. The index case is being presented to discuss the histopathological and immunohistochemical clues to differentiate it from other fibrofatty tumors of childhood.Case report: An 11-month-old male child presented with a slowly growing mass on the upper back. MRI findings were suggestive of an adipocytic tumor. Microscopy revealed a lesion composed of mature adipocytes and intervening fibrous bands with infiltration into the adjacent skeletal muscle, features of lipofibromatosis.Conclusion: Lipofibromatosis should be considered in the differential diagnosis of a pediatric fibrofatty tumor. Accurate diagnosis is essential for proper patient management as incomplete removal of the tumor may result in recurrence.

Aberrant receptor tyrosine kinase signaling in lipofibromatosis: a clinicopathological and molecular genetic study of 20 cases

Lipofibromatosis is a rare pediatric soft tissue tumor with predilection for the hands and feet. Previously considered to represent "infantile fibromatosis", lipofibromatosis has distinctive morphological features, with mature adipose tissue, short fascicles of bland fibroblastic cells, and lipoblast-like cells. Very little is known about the genetic underpinnings of lipofibromatosis. Prompted by our finding of the FN1-EGF gene fusion, previously shown to be a characteristic feature of calcifying aponeurotic fibroma (CAF), in a morphologically typical case of lipofibromatosis that recurred showing features of CAF, we studied a cohort of 20 cases of lipofibromatosis for this and other genetic events. The cohort was composed of 14 males and 6 females (median age 3 years; range 1 month-14 years). All primary tumors showed classical lipofibromatosis morphology. Follow-up disclosed three local recurrences, two of which contained calcifying aponeurotic fibroma-like nodular calcifications in addition to areas of classic lipofibromatosis, and no metastases. By FISH and RNA sequencing, four cases were positive for FN1-EGF and one case each showed an EGR1-GRIA1, TPR-ROS1, SPARC-PDGFRB, FN1-TGFA, EGFR-BRAF, VCL-RET, or HBEGF-RBM27 fusion. FN1-EGF was the only recurrent fusion, suggesting that some cases of "lipofibromatosis" may represent calcifying aponeurotic fibroma lacking hallmark calcifications. Several of the genes involved in fusions (BRAF, EGFR, PDGFRB, RET, and ROS1) encode receptor tyrosine kinases (RTK), or ligands to the RTK EGFR (EGF, HBEGF, TGFA), suggesting a shared deregulation of the PI3K-AKT-mTOR pathway in a large subset of lipofibromatosis cases.

Successful Limb-Sparing Wide Excision of a Giant Lipofibromatosis in a 5-Year-Old Girl

A 5-year-old girl presented with a big painless mass, sized 24 × 37 × 35 cm, in her lower left limb. MRI revealed a huge heterogeneous mass splaying from the left distal femur to the calcaneal region without bony erosion but compressing the arteries and causing bowing of the left tibia and fibula bones. The difficulty was to determine the best course of action taken which would either be limb salvation or amputation. Considering that only a few muscles could be saved, the author initially recommended amputation but still considered a limb-sparing procedure. After a double set-up examination in the operating room, the author ultimately decided to save the affected limb. The salvaged limb was found to be viable after the surgery, and there was no further recurrence over a subsequent 6-month follow-up period. The careful surgical decision is vital in giving the best possible care to the patient.

Lipofibromatosis-like neural tumor: Case report of a unique infantile presentation

A 14-month-old boy presented with a slow-growing, asymptomatic back plaque, which was biopsied and found to have S100 positivity, sparse CD34 staining, and no significant mitotic activity, nuclear pleomorphism, or necrosis; genetic workup found LMNA-NTRK1 gene fusion, overall consistent with lipofibromatosis-like neural tumor (LPF-NT). LPF-NT is rare, with 14 cases previously reported, and our patient is the first report of this diagnosis in infancy. This case report and literature review includes comparison of similar diagnoses including lipofibromatosis, low-grade malignant peripheral nerve sheath tumor, infantile fibrosarcoma, and dermatofibrosarcoma protuberans and serves to aid detection of LPF-NT presenting in pediatric patients by highlighting similarities and differences that should prompt consideration. LPF-NT shows locally aggressive behavior only and should not be confused with conditions that have potential for distant spread. However, case reports of metastasizing LMNA-NTRK1 tumors draw into question whether growths with this gene fusion exist on a spectrum of disease severity. Our patient was treated with wide local excision and has developed no complications or evidence of recurrence with 6 months of follow-up time.

Recurrent NTRK1 Gene Fusions Define a Novel Subset of Locally Aggressive Lipofibromatosis-like Neural Tumors

The family of pediatric fibroblastic and myofibroblastic proliferations encompasses a wide spectrum of pathologic entities with overlapping morphologies and ill-defined genetic abnormalities. Among the superficial lesions, lipofibromatosis (LPF), composed of an admixture of adipose tissue and fibroblastic elements, in the past has been variously classified as infantile fibromatosis or fibrous hamartoma of infancy. In this regard, we have encountered a group of superficial soft tissue tumors occurring in children and young adults, with a notably infiltrative growth pattern reminiscent of LPF, variable cytologic atypia, and a distinct immunoprofile of S100 protein and CD34 reactivity, suggestive of neural differentiation. SOX10 and melanocytic markers were negative in all cases tested. In contrast, a control group of classic LPF displayed bland, monomorphic histology and lacked S100 protein immunoreactivity. To define the pathogenetic abnormalities in these seemingly distinctive groups, we performed RNA sequencing for fusion gene discovery in 2 cases each, followed by screening for any novel alterations identified in a larger cohort representing both entities. The 2 index LPF-like neural tumors (LPF-NT) showed TPR-NTRK1 and TPM3-NTRK1 gene fusions, which were further validated by fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction. Subsequent FISH screening of 14 LPF-NT identified recurrent NTRK1 gene rearrangements in 10 (71%) cases. Of the NTRK1-negative LPF-NT cases, 1 case each showed ROS1 and ALK gene rearrangements. In contrast, none of the 25 classic LPFs showed NTRK1 gene rearrangements, although regional abnormalities were noted in the 1q21-22 region by FISH in a majority of cases. Furthermore, NTRK1 immunostaining was positive only in NTRK1-rearranged S100-positive LPF-NT but negative in classic LPF. These results suggest that NTRK1 oncogenic activation through gene fusion defines a novel and distinct subset of soft tissue tumors resembling LPF, but displaying cytologic atypia and a neural immunophenotype, provisionally named LPF-like neural tumors.

Lipofibromatosis: an institutional and literature review of an uncommon entity

We report six new cases of lipofibromatosis, an uncommon pediatric soft tissue neoplasm. This is the only series of patients to be described since the initial case series of 45 patients that characterized this entity in 2000. The purpose of this study was to characterize the presentation of lipofibromatosis to further define the clinical phenotype of this rare entity. Six patients were diagnosed with lipofibromatosis at our institution from 2000 to 2012. Patient age, sex, and ethnicity were recorded, along with tumor site and size, management, and recurrence data. Half of our patients were younger than 2 years old at presentation and the other half were school age. Boys and girls were affected with equal frequency. In five of six patients, lipofibromatosis presented in its "classic" form as a mass on the distal extremities. These tumors typically measured 1 to 2 cm in diameter, in contrast to case reports in the medical literature highlighting the occurrence of lipofibromatosis of greater size and at varied anatomic sites. The tumors in our series were managed using excision, with recurrence noted in 33%. Lipofibromatosis is an uncommon tumor typically found on the distal extremities of infants, although it can appear in various sizes and locations. It should be considered in the differential diagnosis of pediatric soft tissue neoplasms.

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.

Fibroblastic and myofibroblastic tumors in children and adolescents

Fibroblastic and myofibroblastic tumors in children and adolescents are a relatively common group of soft tissue proliferations that range from reactive to hamartomatous to neoplastic, with a full spectrum of benign, intermediate, and malignant neoplasms. These lesions are diagnostically challenging because of morphologic and immunohistochemical overlap, despite significant clinical, genetic, and prognostic differences. The fibromatoses are a major subgroup, and all types of fibromatoses can occur in the 1st 2 decades of life. Intermediate and malignant fibroblastic-myofibroblastic tumors are an important group that includes variants of fibrosarcoma and other tumors with recurrent cytogenetic or molecular genetic abnormalities and low metastatic potential. Pathologic examination is enhanced by adjunct techniques, such as immunohistochemistry, cytogenetics, and molecular genetics, although morphology provides the ultimate criteria for a specific diagnosis. This article reviews the clinicopathologic features of fibroblastic and myofibroblastic tumors with an emphasis on the unique aspects of these neoplasms in children and adolescents, the use of diagnostic adjuncts, and differential diagnoses.

Pediatric fibroblastic and myofibroblastic lesions

Fibrous lesions of infancy and childhood are a heterogeneous group of entities composed predominantly of fibroblasts and myofibroblasts, ranging from reactive lesions to neoplasms with a range of malignant potential. Although rare, their correct recognition by histopathology is important clinically as they exhibit a wide range of behaviors and may be associated with distinct underlying syndromes. Contributions from molecular diagnostics have enabled more accurate diagnosis, and have changed our concepts of some tumor types. In this review, we discuss the clinicopathologic spectrum of fibroblastic and myofibroblastic lesions of childhood and adolescence.

[Lipofibromatosis in the finger of a child]

BACKGROUND

Lipofibromatosis is a recently classified form of benign tumor in children; it is of non-specific clinical presentation and is seen mainly on the extremities. We report a case involving the index finger of a child.

PATIENTS AND METHODS

An 8-year-old boy consulted for a nodule on the palmar surface of the left index finger that had appeared 6 months earlier. The nodule, which adhered to the deeper skin, measured 1cm in diameter and was bluish and firm on palpation. Histological examination of the resected specimen revealed fatty tissue associated with a proliferation of spindle cells. Immunohistochemical analysis showed that certain of these cells expressed smooth muscle actin, suggesting partial myofibroblastic differentiation. A diagnosis of lipofibromatosis was made.

DISCUSSION

Lipofibromatosis is a rare tumor. The main problem in terms of severity is its locally invasive development, which frequently causes problems for resection. Due to the age at onset, its course with deep invasion, the frequency of recurrence and the histological aspect, lipofibromatosis is classed as a form of childhood fibromatosis.

Orbital lipofibromatosis in a child: a case report

PURPOSE

Lipofibromatosis is a rare, benign, soft tissue tumor that typically involves extremities particularly in children. We report a young girl with lipofibromatosis involving the superotemporal quadrant of the left orbit.

CASE REPORT

An 8-year-old girl presented with a history of a gradually expanding mass in the superotemporal quadrant of the left orbit over several years. Orbital imaging showed a soft tissue mass superolateral to the globe with possible infiltration into the lacrimal gland and lateral rectus muscle. The lesion was excised preserving adjacent structures. Histopathological examination revealed that the lesion consisted of adipose tissue with fibroblastic elements, being consistent with a diagnosis of lipofibromatosis. No recurrence of the lesion was seen in 18 months follow-up.

COMMENT

Orbital involvement of lipofibromatosis as reported here is indeed a very rare entity. Diagnosis can be confirmed by histopathological analysis. As the lesion has a tendency to infiltrate into surrounding structures, surgical excision without hampering important structures is a treatment of choice.

[Lipofibromatosis in a 6-year-old girl: a case report]

Lipofibromatosis is a typical soft tissue lesion of childhood which is most likely underdiagnosed. The case of a 6-year-old girl with a palmar tumor is presented. The lesion showed a typical fascicular growth patter into the fatty tissue. Differential diagnosis includes fibrous hamartoma of infancy. Lipofibromatosis is a benign disease but recurrences are not unusual.