Unusual presentation of congenital infantile fibrosarcoma in seven infants with molecular-genetic analysis

Kinase fusion positive intra-osseous spindle cell tumors: A series of eight cases with review of the literature

Mesenchymal spindle cell tumors with kinase fusions, often presenting in superficial or deep soft tissue locations, may rarely occur in bone. Herein, we describe the clinicopathologic and molecular data of eight bone tumors characterized by various kinase fusions from our files and incorporate the findings with the previously reported seven cases, mainly as single case reports. In the current series all but one of the patients were young children or teenagers, with an age range from newborn to 59 years (mean 19 years). Most tumors (n = 5) presented in the head and neck area (skull base, mastoid, maxilla, and mandible), and remaining three in the tibia, pelvic bone, and chest wall. The fusions included NTRK1 (n = 3), RET (n = 2), NTRK3 (n = 2), and BRAF (n = 1). In the combined series (n = 15), most tumors (73%) occurred in children and young adults (<30 years) and showed a predilection for jaw and skull bones (40%), followed by long and small tubular bones (33%). The fusions spanned a large spectrum of kinase genes, including in descending order NTRK3 (n = 6), NTRK1 (n = 4), RET (n = 2), BRAF (n = 2), and RAF1 (n = 1). All fusions confirmed by targeted RNA sequencing were in-frame and retained the kinase domain within the fusion oncoprotein. Similar to the soft tissue counterparts, most NTRK3-positive bone tumors in this series showed high-grade morphology (5/6), whereas the majority of NTRK1 tumors were low-grade (3/4). Notably, all four tumors presenting in the elderly were high-grade spindle cell sarcomas, with adult fibrosarcoma (FS)-like, malignant peripheral nerve sheath tumor (MPNST)-like and MPNST phenotypes. Overall, 10 tumors had high-grade morphology, ranging from infantile and adult-types FS, MPNST-like, and MPNST, whereas five showed benign/low-grade histology (MPNST-like and myxoma-like). Immunohistochemically (IHC), S100 and CD34 positivity was noted in 57% and 50%, respectively, while co-expression of S100 and CD34 in 43% of cases. One-third of tumors (4 high grade and the myxoma-like) were negative for both S100 and CD34. IHC for Pan-TRK was positive in all eight NTRK-fusion positive tumors tested and negative in two tumors with other kinase fusions. Clinical follow-up was too limited to allow general conclusions.

Infantile fibrosarcoma of the perineum with dorsal metastasis in a neonate: a case report original

BACKGROUND

Infantile fibrosarcoma is a rare pediatric soft tissue tumor and usually appears in children before one year of age. Distal extremities constitute the most frequently affected locations, and other tissues such as the trunk, head and neck, gut, sacrococcygeal region, and viscera are uncommon sites.

CASE PRESENTATION

We describe a rare case of infantile fibrosarcoma arising from the perineum. First, a cystic mass was detected using prenatal ultrasonography, and then an echo was changed in serial ultrasound examinations. A solid cystic lesion was found at term; a hypoechoic lesion occurred in the back. The tumor became so large that massive bleeding occurred, which then underwent surgical resection. Pathological examination confirmed infantile fibrosarcoma.

CONCLUSION

Our report demonstrates not all ultrasonographic findings in cases of infantile fibrosarcoma exhibit a solid mass during the initial examination - an early-stage lesion may reveal a cystic echo. Infantile fibrosarcoma has a good prognosis and surgery constitute the main treatment, with adjuvant chemotherapy being received if necessary.

Fine needle aspiration cytology of the primitive myxoid mesenchymal tumor of infancy

Primitive myxoid mesenchymal tumor of infancy (PMMTI) is a recently described entity, previously included under the umbrella of undifferentiated sarcomas. These tumors are notorious for recurrence, chemoresistance and may even metastasize. We describe here, for the first time, the cytomorphology of PMMTI. Further, we discuss the morphological differentials and relevant immunocytochemical markers to reach a correct diagnosis. Knowledge about the distinctive cytomorphological features with characteristic immunocytochemistry is the key to the challenging diagnosis of PMMTI. Establishing the diagnosis on cytology is not difficult in cases of recurrence when such a history is forthcoming. These tumors are a rarity, and awareness of cytomorphology and employment of ancillary techniques is diagnostic, guiding the appropriate therapeutic management.

Intestinal infantile fibrosarcoma with translocation of NTRK. A case report and review of the literature

INTRODUCTION

Infantile fibrosarcoma is a rare non-rhabdomyosarcomatous soft tissue tumor (0.0005%) of which only 10% occur in the abdomen where they rarely affect the gastrointestinal tract. The median age at diagnosis is 3 months although 40% of them are present at birth.

MATERIAL AND METHODS

When infantile fibrosarcoma is diagnosed in our center, a clinical-pathological description is made together with a bibliographic review.

RESULTS

We present the case of a 6-day-old girl who presented with irritability and rejection of food. She was diagnosed with acute abdomen due to perforation and underwent surgery where a mass on the ascending colon was removed. Histopathology revealed a proliferation of spindle cells consisting of intertwined fascicles, infiltrating the adjacent tissues. Nuclear pleomorphism, few mitoses, foci of necrosis and hemorrhage are seen. Immunohistochemistry showed positivity for Pan-TRK and the NGS panel (Archer DX) demonstrated the TPR::NTRK1 fusion. No case with these characteristics, location or TPR::NTRK1 fusion were found in the literature.

CONCLUSIONS

Infantile fibrosarcoma is a very infrequent tumor which is exceptionally rare in the intestine. It is important to look for the characteristic genetic rearrangement of these tumors both to confirm the diagnosis and differentiate them from other pediatric spindle cell tumors and determine the correct targeted treatment. Selective TRK inhibitors have shown a 75% response rate in children and adults with tumors that exhibit TRK fusion. It was possible to find fusions with the Archer DX panel that the Oncomine panel did not detect.

Fetal Mediastinal Fibrosarcoma. Report of Two Cases

Introduction: One-third of fetal soft tissue tumors are malignant and include congenital fibrosarcoma (CF). We report two fetal CFs arising in the posterior mediastinum. Case Presentation: In case 1, the CF resulted in a mediastinal shift, extensive infiltration of the tumor around adjacent structures, pulmonary hypoplasia, pleural effusion, and rapid growth. The pregnancy was terminated. Case 2 had multiple intrathoracic masses, thoracic hypoplasia, pleural effusion, and fetal death. Both were diagnosed as fibrosarcoma at fetopsy. Discussion: Although congenital CF tends to be locally aggressive with a low metastatic rate, it tends to grow rapidly and the tumor location can affect fetal survival. In Case 1, the tumor demonstrated locally aggressive behavior whereas multiple distant metastases such as lung, liver, adrenals, and left eye were detected in Case 2. The tumor was directly responsible for intrauterine fetal demise in the second case.

Adult NTRK-rearranged spindle cell neoplasms of the viscera: with an emphasis on rare locations and heterologous elements

NTRK-rearranged mesenchymal neoplasms mostly affect the soft tissues of pediatric patients. Given the responsiveness to selective NTRK inhibitors, it remains critical to identify those ultra-rare cases occurring in the viscera of adults. In five females and two males aged 18-53 years, we characterized visceral mesenchymal tumors harboring TPM3-NTRK1 [uterine cervix (N = 2), pleura, prostate], LMNA-NTRK1 (lung), SQSTM1-NTRK3 (heart), and NTRK3 rearrangement with unknown fusion partner (colon/mesocolon) with RNA sequencing, FISH, RT-PCR, and immunohistochemistry. The tumors exhibited spindled to ovoid/epithelioid or pleomorphic cells, often arranged in fascicles, and were low-to-intermediate-grade and high-grade in three and four cases, respectively. Keloid-like stromal collagen and perivascular hyalinization was noted in five. Adenosarcoma-like appearances were observed in two, manifesting frond-like protrusions in one cervical tumor and phyllodes-like architecture in the prostatic tumor. Abrupt high-grade transformation into pleomorphic liposarcoma was found in another cervical tumor, while the pleural tumor contained intermixed rhabdomyoblasts. Pan-TRK immunostaining was positive in all cases. All cases expressed CD34, while five were S100-positive. CDKN2A homozygous deletion with concomitant p16 loss occurred in 4/7. Whole-exome sequencing identified TP53 mutation (c.672+2T>C, involving a splice site, with concomitant protein loss) in a cervical sarcoma, limited to its heterologous liposarcomatous component. At least moderate pan-TRK immunoreactivity was present in varying proportions of potential pathologic mimics, with BCOR-positive sarcoma (56%, 5/9), undifferentiated uterine sarcoma (50%, 3/6), and spindle cell/sclerosing rhabdomyosarcoma (33%, 2/6) being among the most frequent. This underscored the unsatisfactory specificity of pan-TRK immunohistochemistry and warranted molecular confirmation in the diagnosis of adult NTRK-rearranged visceral mesenchymal neoplasms. The current report highlights the ever-expanding clinicopathologic and genetic spectrum of this entity by describing the unprecedented cardiac and pleural locations and heterologous differentiation, as well as the second NTRK-rearranged "prostatic stromal sarcoma," while substantiating CDKN2A deletion as a frequent occurrence.

The impact of local control in the treatment of children with advanced infantile and adult-type fibrosarcoma: Experience of the cooperative weichteilsarkom studiengruppe (CWS)

BACKGROUND AND OBJECTIVES

This study aims at examining the potential survival benefits of primary versus secondary surgery of children diagnosed with advanced infantile (iFS) and adult-type fibrosarcoma (aFS).

METHODS

Treatment and outcome of 89 children with FS treated within prospective Cooperative Studiengruppe (CWS) trials (1981-2016) were analyzed retrospectively.

RESULTS

Localized disease (LD) was diagnosed in 87 patients: 64/66 patients with iFS (≤2 years) and 23 with aFS (>2 ≤ 18 years). Two patients (iFS) had metastatic disease. Resection was the mainstay of therapy of patients with LD resulting in microscopically complete (R0, IRS group I) (n = 29/87, 33%), microscopically incomplete (R1, IRS group II) (n = 17/87, 20%) and macroscopically incomplete (R2, IRS group III) (n = 41/87, 47%). Advanced LD (IRS group III) was present in 32/64 (50%) patients with iFS and in 9/23 (39%) with aFS. Chemotherapy was added predominantly in patients with advanced disease and an assessable objective response to CHT was seen in 71% iFS and 75% aFS. The 5-year event-free survival (EFS) of patients with iFS and aFS was 81% (±10, 95% CI) and 70% (±19, 95% CI) (p = 0.24); the 5-year overall survival (OS) was 98% (±3, 95% CI) and 82% (±16, 95% CI) (p = 0.02). Primary resection was no prognostic factor. Secondary R0/ R1 resection in patients with advanced disease improved 5-year EFS and OS in aFS (p = 0.002 and p = 0.000) but not in infants.

CONCLUSIONS

Secondary resection improves outcome in advanced aFS but not in infants. Mutilating surgery in infants should be avoided.

TYPE OF STUDY AND LEVEL OF EVIDENCE

Treatment study: patients were enrolled in five prospective studies and one registry, prognosis study: retrospective study.

LEVEL OF EVIDENCE

II/ III.

MINI-ABSTRACT

Fibrosarcoma is a very rare malignant tumor. Little is known about differences of local treatment of advanced infantile and adult-type. Data of 89 patients registered in five prospective trials and one registry of the Cooperative Weichteilsarkom Studiengruppe (CWS) (1981-2016) were analyzed.

MRI of Rhabdomyosarcoma and Other Soft-Tissue Sarcomas in Children

Soft-tissue sarcomas in children comprise a heterogeneous group of entities with variable manifestation depending on the age of the patient and the location of the tumor. MRI is the modality of choice for evaluating musculoskeletal soft-tissue tumors and plays a paramount role in both initial diagnosis and assessment of tumor response during and after treatment. Conventional MRI sequences, such as T1- and T2-weighted imaging, offer morphologic information, which is important for localizing the lesion and describing anatomic relationships but not accurate for determining its malignant or benign nature and may be limited in differentiating tumor response from therapy-related changes. Advanced multiparametric MRI offers further functional information that can help with these tasks by using different imaging sequences and biomarkers. The authors present the role of MRI in rhabdomyosarcoma and other soft-tissue sarcomas in children, emphasizing a multiparametric approach with focus on the utility and potential added value of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI in characterization and staging, determination of pretreatment extent, and evaluation of tumor response and recurrence after treatment. ^©RSNA, 2020.

Primary Lung Tumors in Children: Radiologic-Pathologic Correlation From the Radiologic Pathology Archives

Primary lung tumors in children are rare, with a narrow range of diagnostic considerations. However, the overlapping imaging appearances of these tumors necessitate attention to key discriminating imaging and pathologic features. In the neonate and infant, the important considerations include pleuropulmonary blastoma (PPB), infantile fibrosarcoma, and fetal lung interstitial tumor. Among these tumors, imaging findings such as air-filled cysts in type 1 PPB and homogeneously low attenuation of fetal lung interstitial tumors are relatively specific. Key pathologic and genetic discriminators among this group of tumors include the DICER1 germline mutation found in PPB and the t(12,15)(p13;q25) translocation and ETV6-NTRK3 fusion gene seen in infantile fibrosarcoma. Primary lung tumors in older children include inflammatory myofibroblastic tumors (IMTs), carcinoid salivary gland-type tumors of the lung, recurrent respiratory papillomatosis, and other rare entities. IMT, a spindle-cell proliferation with inflammatory elements, is the most common lung tumor in children. Anaplastic lymphoma kinase, a receptor-type protein tyrosine kinase, is present in 50% of these tumors, and this finding may support an imaging diagnosis of IMT. Carcinoid tumors account for a substantial portion of childhood lung tumors, and their characteristic avid enhancement on images corresponds to the compressed fibrovascular stroma histologically. Furthermore, novel imaging agents used with somatostatin receptor analogs have an emerging role in the evaluation of carcinoid tumors. Although less common than mucoepidermoid carcinoma, adenoid cystic carcinoma tends to recur given the perineural spread seen histologically. Integrating radiologic and pathologic knowledge is critical to accurate diagnosis, treatment planning, and surveillance of primary lung tumors in children.

Congenital infantile fibrosarcoma of the glabella: Nuances of achieving surgical cure without cosmetic or functional deformity

Congenital Infantile Fibrosarcoma is a rare neoplasm that typically presents during the first year of life, but uncommonly in the head and neck. We report a six-day old male presenting with an expanding mass of the right glabella associated with visual field obstruction. The patient underwent a two-staged procedure for surgical removal of the tumor due to the initially unclear pathologic diagnosis of the tumor, combined with the desire to close the defect while incurring minimal aesthetic or functional deformity. We describe this patient's postnatal presentation and curative surgical management and review the relevant literature to date.

Endoscopic Transnasal Transpterygoid Excision of an Infratemporal Dermoid Cyst

OBJECTIVE

Intracranial dermoid cysts are rare, slow-growing masses of sellar, parasellar regions, and posterior cranial fossa. The symptomatology of these cysts depends on the localization and presence of rupture. The preoperative diagnosis of these cysts by imagining techniques is distinctive as they have characteristic appearances.

PATIENT

Endoscopic transnasal transpterygoid approach to infratemporal fossa for an extradural dermoid cyst of a 24 year-old woman is presented in this clinical report. Headache, dizziness, and retro orbital pain were her main complaints and diagnostic imagining studies designated an intracranial dermoid cyst preoperatively. The cyst was excised uneventfully with no recurrence 6 months after the operation.

CONCLUSION

Surgery of intracranial lesions neighboring critical vital neurovascular structures can be challenging to the surgeon. Alternative minimal invasive approaches should always be considered for averting life-threatening complications.

Neonatal congenital lung tumors - the importance of mid-second-trimester ultrasound as a diagnostic clue

BACKGROUND

The differential diagnosis for primary lung masses in neonates includes a variety of developmental abnormalities; it also consists of the much rarer congenital primary lung tumors: cystic pleuropulmonary blastoma (cystic PPB), fetal lung interstitial tumor (FLIT), congenital peribronchial myofibroblastic tumor (CPMT), and congenital fibrosarcoma. Radiologic differentiation between malformations and tumors is often very challenging.

OBJECTIVE

The objective was to establish distinctive features between developmental pulmonary abnormalities and primary lung tumors.

MATERIALS AND METHODS

We conducted a retrospective study of 135 congenital lung lesions at a university mother and child center over a period of 10 years (2005-2015). During this time, we noted four tumors (two cystic PPBs and two FLITs) and 131 malformations. We recorded the following parameters: timing of conspicuity in utero (mid-second trimester, third trimester, or not seen prenatally), presence of symptoms at birth, prenatal and perinatal radiologic findings, and either histological diagnoses by pathology or follow-up imaging in non-operated cases.

RESULTS

All lesions except the four tumors were detected during mid-second-trimester ultrasound. In none of the tumors was any pulmonary abnormality found on the mid-second-trimester sonogram, contrary to the developmental pulmonary abnormalities.

CONCLUSION

The timing of conspicuity in utero appears to be a key feature for the differentiation between malformations and tumors. Lesions that were not visible at the mid-second-trimester ultrasound should be considered as tumor. A cystic lung lesion in the context of a normal mid-second-trimester ultrasound is highly suggestive of a cystic PPB. Differentiating the types of solid congenital lung tumors based upon imaging features is not yet feasible.

ETV6-NTRK3 Is Expressed in a Subset of ALK-Negative Inflammatory Myofibroblastic Tumors

Inflammatory myofibroblastic tumor (IMT) is a genetically heterogenous tumor of the viscera and soft tissues, with multiple molecular features having been demonstrated in this tumor type. About 50% of cases harbor an anaplastic lymphoma kinase (ALK) gene rearrangement, and recent studies have described novel fusions involving the ROS1 and PDGFRβ genes in a subset of ALK-negative cases. However, the molecular features of the remaining subset of cases are not yet defined. We report a case of a large, highly aggressive IMT of the lung in a 17-year-old girl. This case was molecularly characterized through whole-genome and transcriptome sequencing. Subsequently, we investigated a cohort of 15 ALK-negative IMTs of various anatomic sites. All cases were screened using fluorescence in situ hybridization (FISH) for rearrangement of the ETV6 locus and with reverse transcription polymerase chain reaction (RT-PCR) for the ETV6-NTRK3 fusion transcript. Whole-genome and transcriptome sequencing revealed an ETV6-NTRK3 fusion transcript in our index case. This was confirmed by FISH studies for ETV6 gene rearrangement, as well as by RT-PCR. In addition, 2 additional cases in our cohort demonstrated ETV6 rearrangement by FISH. The presence of ETV6-NTRK3 fusion transcript was demonstrated by RT-PCR in one of these additional cases. In summary, we demonstrate the expression of the ETV6-NTRK3 fusion oncogene in a small subset of IMTs, lending further support to the role of oncogenic tyrosine kinases in the pathophysiology of this tumor type. Our data also further expand the growing spectrum of tumor types expressing the ETV6-NTRK3 fusion.

Primitive Spindle Cell Neoplasm of Ileum with Extensive Heterotopic Cartilage, Presenting as Acute Abdomen in a 6-Day-Old Neonate

Neonatal intestinal masses with spindle cell morphology have broad differential diagnoses and require a multidisciplinary approach to make the final diagnosis. Spindle cell masses with heterotopic cartilage in the gastrointestinal tract are very rare, and, to our knowledge, have not previously been reported in the neonate. Here we present a case of intestinal primitive spindle cell neoplasm with extensive heterotopic cartilage that manifested initially as acute abdomen in a 6-day-old term infant. Plain radiography demonstrated pneumoperitoneum, prompting diagnostic laparotomy that identified a perforated mass involving the midileum. Histologic and immunohistochemical examination demonstrated an infiltrative spindle cell tumor most compatible with infantile fibrosarcoma (IFS) by a process of exclusion, with nodules of mature heterotopic cartilage. Additional staging studies did not reveal any evidence of residual or metastatic disease. Recognition of this rare variant of IFS will aid in differentiation from other neonatal intestinal mesenchymal tumors.

Conservative strategy in infantile fibrosarcoma is possible: The European paediatric Soft tissue sarcoma Study Group experience

BACKGROUND

Infantile fibrosarcoma (IFS) is a very rare disease occurring in young infants characterised by a high local aggressiveness but overall with a favourable survival. To try to reduce the total burden of therapy, the European pediatric Soft tissue sarcoma Study Group has developed conservative therapeutic recommendations according to initial resectability.

MATERIAL AND METHODS

Between 2005 and 2012, children with localised IFS were prospectively registered. Initial surgery was suggested only if possible without mutilation. Patients with initial complete (IRS-group I/R0) or microscopic incomplete (group II/R1) resection had no further therapy. Patients with initial inoperable tumour (group III/R2) received first-line vincristine-actinomycin-D chemotherapy (VA). Delayed conservative surgery was planned after tumour reduction. Aggressive local therapy (mutilating surgery or external radiotherapy) was discouraged.

RESULTS

A total of 50 infants (median age 1.4 months), were included in the study. ETV6-NTRK3 transcript was present in 87.2% of patients where investigation was performed. According to initial surgery, 11 patients were classified as group I, 8 as group II and 31 as group III. VA chemotherapy was first delivered to 25 children with IRS-III/R2 and one with IRS-II/R1 disease. Response rate to VA was 68.0%. Mutilating surgery was only performed in three cases. After a median follow-up of 4.7 years (range 1.9-9.0), 3-year event-free survival and overall survival were respectively 84.0% (95% confidence interval [CI] 70.5-91.7) and 94.0% (95% CI 82.5-98.0).

CONCLUSIONS

Conservative therapy is possible in IFS as only three children required mutilating surgery, and alkylating or anthracycline based chemotherapy was avoided in 71.0% of patients needing chemotherapy. VA regimen should be first line therapy in order to reduce long term effects.

Fetal tumors: prenatal ultrasonographic findings and clinical characteristics

The incidence of fetal tumors has been increased due to generalization of prenatal evaluation and improvement of imaging techniques. The early detection of a fetal tumor and understanding of its imaging features are very important for fetal, maternal, and neonatal care. Ultrasonography is usually used for the detection and differential diagnosis of fetal tumors, and magnetic resonance imaging is increasingly being used as a complementary study. Many fetal tumors have different clinical and imaging features compared with pediatric tumors. Although several fetal tumors may mimic other common anomalies, some specific imaging features may carry early accurate diagnosis of fetal tumors, which may alter the prenatal management of a pregnancy and the mode of delivery, and facilitate immediate postnatal treatment.

Primary giant congenital infantile fibrosarcoma of the left forearm

Infantile fibrosarcoma is a rare soft tissue tumor in the infant, and only a few cases have been reported as congenital. We report a case of congenital infantile fibrosarcoma of the left forearm at birth. An amputation was performed because the tumor was relapsed soon after surgical removal, and associated with anabrosis and bleeding.

A case of congenital infantile fibrosarcoma of sigmoid colon manifesting as pneumoperitoneum in a newborn

Congenital infantile fibrosarcoma (CIF) is a rare soft-tissue tumor in the pediatric age group and seldom involves the gastrointestinal tract. A 2-day-old boy was transferred to our hospital with a pneumpoperitoneum. After emergency operation, we could find a solid mass wrapping around a sigmoid colon and performed a segmental resection of sigmoid colon including a mass. Histopathologic examination showed an infantile fibrosarcoma origining from the muscular layer of colon. The baby was discharged on the 17th hospital day and followed for 1 yr without recurrence.

[Fibrosarcoma in children and adolescents: different entities for the same name]

Fibrosarcomas (FS) are rare malignant tumors in pediatrics, classified in the heterogeneous non-rhabdomyosarcomas group of malignant mesenchymal tumors. Infantile FS are found typically in children less than 2 years of age, and include congenital FS usually occurring in infants in the first 3 months of life. Histological diagnosis can be difficult; and confirmed with detection by molecular biology of the ETV6-NTRK3 fusion protein. FS is most often a localized disease at diagnosis, with involvement of an extremity. The management of these patients must be multidisciplinary, to define the different phases of treatment and avoid mutilating surgery. Cellular or atypical mesoblastic nephroma (MN) is a subtype of malignant pediatric renal tumors, most often present in children of less than 3 months. Histopathological characteristics of the cellular MN are very close to the congenital FS due to a fusion transcript common to both diseases. Treatment schedule is defined by initial local stage of the disease. FS called "adult-type" found exceptionally in childhood occur most often after 10 years old. Adult FS differ from infantile FS in their clinical presentation because of a strong local aggressiveness and problematic appearance of metastasis in 50% of cases, sometimes late. These three diseases present therefore histological similarities. Both have a common name but different clinical presentation and outcome: infantile FS and adult FS. Two have different names and initial location but similar histology, chromosomal rearrangement, sensitivity to chemotherapy and outcome: the congenital FS and cellular mesoblatic nephroma. Authors present a review of the literature of these entities.