Undifferentiated myxoid lipoblastoma with PLAG1-HAS2 fusion in an infant; morphologically mimicking primitive myxoid mesenchymal tumor of infancy (PMMTI)--diagnostic importance of cytogenetic and molecular testing and literature review

Head and neck lipoblastoma in children: A case report and systematic review

BACKGROUND

Lipoblastoma is a rare and benign tumor arising from embryonal fat cells. It develops primarily in infancy and early childhood. We present a case study of a 10-month-old child treated for an extensive tumor of the infratemporal fossa and parapharyngeal space. The systematic review of 60 reports in 80 children with lipoblastoma of the head and neck is also reported.

MATERIAL AND METHODS

Systematic review of all articles included lipoblastomas of the head and neck area in children published from 1964 to 2022 in the PubMed database was conducted. Clinical presentation of extensive lipoblastoma of the head and neck in a child.

RESULTS

On the basis of all inclusion criteria 83 articles were identified concerning pediatric lipoblastoma. There were 36 F (45%) and 39 M (48%), in 6 patients, (7%) gender was not specified. Ages ranged from 0mth (6h) to 15 yo (180mth). The tumor was located in the head in 22 (27%) cases, while the neck area accounted for 53 (65%) cases. General description without precise location was shown in 6 (7%) cases. All patients underwent complete surgical excision. Post surgical recurrence was noted in 6% clinical cases in the analyzed articles.

CONCLUSIONS

Lipoblastoma is characterized by a rapidly growing predominantly adipose mass. The treatment of choice is complete surgical excision. In selected cases when the pathology is hard to reach, as a consequence of the extensive penetration of the mass, we recommend performing the procedure with an interdisciplinary team. Endoscopy assistance and microdebrider significantly facilitated the removal of pathology in the described advanced case of lipoblastoma. This is the only case reported in the pediatric literature of a head and neck lipoblastoma, where due to extensive involvement and location of the disease the cranial nerves V2 and inferior alveolar branch of V3 could not be spared. Long-term follow-up even to 10 years is required because there is a reported tendency for these tumors to recur.

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.

Lipoblastoma in one adult and 35 pediatric patients: Retrospective analysis of 36 cases

Lipoblastoma is a rare benign mesenchymal neoplasm that typically occurs at various sites in infants and children but may also occur in adults. Thus, differential diagnoses are often performed. To understand this tumor type, the present study described clinicopathological features, diagnosis and differential diagnosis of different morphological lipoblastomas. A single-institution retrospective review of 36 lipoblastoma cases diagnosed between 2015 and 2021 was performed. Formalin-fixed paraffin-embedded tissue was used for S-100, CD34, P16 and desmin immunohistochemistry analysis, along with rapid fluorescence in situ hybridization (FISH) detection with pleiomorphic adenoma gene 1 (PLAG1). The 36 cases included 14 females and 22 males [age range, 7 days to 33 years (median, 16.5 years); 28 patients were aged ≤3 years] and the tumors were located in the trunk (n=16), limbs (n=12), head and neck (n=6), and perineum (n=2). Histologically, lipoblastomas were divided into classic (n=15), lipoma-like (n=13) and myxoid (n=8) subtypes. They comprised lobules of mature adipose tissue of varying size and a fine capillary network surrounded by mucinous stroma. Single- or multivesicular lipoblasts positive for S-100 (29/36, 81%) were observed, with occasional mature adipocytes. Peripheral vessels and cytoplasm of primitive mesenchymal cells were diffusely positive for CD34 (36/36, 100%), whereas primitive mesenchymal cells and striated muscle tissue were positive for desmin (26/36, 72%). Most tumor cells were negative while only few were positive for P16 (8/36, 22%). FISH revealed PLAG1 breakage and rearrangement in 24/32 (75%) patients. In total, 28 patients were followed up post-operatively (range, 2-84 months; median, 41 months; 3 patients relapsed and 8 were lost to follow-up). In conclusion, diagnosis of a typical lipoblastoma is not difficult and PLAG1 breakage detection is key for the diagnosis.

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.

PLAG1 Immunohistochemical Staining Is a Surrogate Marker for PLAG1 Fusions in Lipoblastomas

BACKGROUND

The hallmark of lipoblastoma is a PLAG1 fusion. PLAG1 protein overexpression has been reported in sporadic PLAG1-rearranged lipoblastomas.

METHODS

We evaluated the utility of PLAG1 immunohistochemical staining (IHC) in 34 pediatric lipomatous tumors, correlating the results with histology and conventional cytogenetics, FISH and/or next generation sequencing (NGS) results.

RESULTS

The study included 24 lipoblastomas, divided into 2 groups designated as "Lipoblastoma 1" with both lipoblastoma histology and PLAG1 rearrangement (n = 16) and "Lipoblastoma 2" with lipoblastoma histology but without PLAG1 cytogenetic rearrangement (n = 8), and 10 lipomas with neither lipoblastoma histology nor a PLAG1 rearrangement. Using the presence of a fusion as the "gold standard" for diagnosing lipoblastoma (Lipoblastoma 1), the sensitivity of PLAG1 IHC was 94%. Using histologic features alone (Lipoblastoma 1 + 2), the sensitivity was 96%. Specificity, as defined by the ability to distinguish lipoma from lipoblastoma, was 100%, as there were no false positives in the lipoma group.

CONCLUSIONS

Cytogenetics/molecular testing is expensive and may not be ideal for detecting PLAG1 fusions because PLAG1 fusions are often cytogenetically cryptic and NGS panels may not include all partner genes. PLAG1 IHC is an inexpensive surrogate marker of PLAG1 fusions and may be useful in distinguishing lipoblastomas from lipomas.

Imaging of head and neck lipoblastoma: case report and systematic review

Lipoblastoma is a rare and benign tumour arising from embryonal fat cells, predominantly diagnosed in children younger than 3 years old. The most frequent locations are the extremities and trunk, while the head and neck areas are more rarely affected (10-15% of total cases). Clinically, the most common presentation is a fast-growing painless mass. Ultrasound is the first-line imaging examination, but Magnetic Resonance Imaging (MRI) allows for better definition of the relationships with the adjacent vascular and muscular structures. It can help to identify the lipomatous components, and it is useful for preoperative planning. However, the definitive diagnosis is provided by histopathological examination. Complete surgical excision is the first-line treatment, with a good prognosis in case of total eradication. We report the case of a 7-month-old male child with a rapidly growing mass that had typical radiological features of lipoblastoma.

Interstitial Deletions Generating Fusion Genes

A fusion gene is the physical juxtaposition of two different genes resulting in a structure consisting of the head of one gene and the tail of the other. Gene fusion is often a primary neoplasia-inducing event in leukemias, lymphomas, solid malignancies as well as benign tumors. Knowledge about fusion genes is crucial not only for our understanding of tumorigenesis, but also for the diagnosis, prognostication, and treatment of cancer. Balanced chromosomal rearrangements, in particular translocations and inversions, are the most frequent genetic events leading to the generation of fusion genes. In the present review, we summarize the existing knowledge on chromosome deletions as a mechanism for fusion gene formation. Such deletions are mostly submicroscopic and, hence, not detected by cytogenetic analyses but by array comparative genome hybridization (aCGH) and/or high throughput sequencing (HTS). They are found across the genome in a variety of neoplasias. As tumors are increasingly analyzed using aCGH and HTS, it is likely that more interstitial deletions giving rise to fusion genes will be found, significantly impacting our understanding and treatment of cancer.

Pediatric fibromyxoid soft tissue tumor with PLAG1 fusion: A novel entity?

The classification of undifferentiated soft tissue tumors continues to evolve with the expanded application of molecular analysis in clinical practice. We report three cases of a unique soft tissue tumor in young children (5 months to 2 years old) displaying a purely fibromyxoid histology, with positive staining for desmin and CD34. In two cases, RNA sequencing detected a YWHAZ-PLAG1 gene fusion, while in the third case, a previously unreported EEF1A1-PLAG1 fusion was identified. PLAG1 fusions have been reported in several pathologic entities including pleomorphic adenoma, myoepithelial tumors of skin and soft tissue, and lipoblastoma, the latter occurring preferentially in young children. In these tumors, expression of a full length PLAG1 protein comes under the control of the constitutively active promoter of the partner gene in the fusion, and the current cases conform to that model. Overexpression of PLAG1 was confirmed by diffusely positive immunostaining for PLAG1 in all three cases. Our findings raise the possibility of a novel fibromyxoid neoplasm in childhood associated with these rare PLAG1 fusion variants. The only other report of a PLAG1-YWHAZ fusion occurred in a pediatric tumor diagnosed as a "fibroblastic lipoblastoma." This finding raises the possibility of a relationship with our three cases, even though our cases lacked any fat component. Further studies with regard to a shared pathogenesis are required.

Primitive Myxoid Mesenchymal Tumor of Infancy in the Orbit: A New Location for a Rare Tumor

Primitive myxoid mesenchymal tumor of infancy is a rare subtype of sarcoma. With the advent of relevant immunohistochemical and genetic analysis, it was defined by Alaggio et al. in a 2006 case series. Since then, 25 further cases are described in the literature-arising variably from the neck, chest, scalp, abdomen, back, or limbs. Here it is described for the first time arising in the orbit, confirmed by identification of BCOR immunopositivity with internal tandem duplication. All specialties involved in the management of orbital masses should be aware of the subtypes of sarcomas found in the orbit as approaches to their management may change depending on the diagnosis. As more cases are identified, a better understanding of this tumor's clinical behavior and appropriate management can be established.

Lipoblastomas presenting in older children and adults: analysis of 22 cases with identification of novel PLAG1 fusion partners

Lipoblastomas are benign neoplasms of embryonal white fat that typically present in the first 3 years of life and show a lobular arrangement of maturing adipocytes with variable degrees of myxoid change. We systematically studied the clinicopathologic and genetic features of lipoblastomas arising in older children and adults. Cases with a diagnosis of lipoblastoma or maturing lipoblastoma in patients >3 years of age were retrieved from our archives. Immunostaining for CD34 and desmin and molecular studies (FISH, RNA sequencing) were performed. Twenty-two cases (8F; 14M) were identified in patients ranging from 4 to 44 years of age (median 10 years). Sites included extremity (n = 15), head and neck (n = 4), and trunk (n = 3) with tumor sizes varying from 1.6 to 17.5 cm (median 5). Only three tumors had histologic features of "conventional" lipoblastoma. The majority of tumors (n = 14) were composed of variably sized lobules of mature adipose tissue partitioned by thin fibrous septa ("maturing"). The remaining five cases consisted predominantly of bland spindled to plump ovoid cells embedded in a fibrous stroma, with a vaguely plexiform arrangement of small myxoid and adipocytic nodules ("fibroblastic"). CD34 was diffusely positive in all cases tested (21/21), while desmin immunoreactivity was identified in 12 of 21 cases (diffuse = 7, focal = 5). PLAG1 rearrangements were identified in 13 tumors in the entire cohort (59%), including all 5 fibroblastic tumors. RNA sequencing detected eight PLAG1 fusion partners, of which two were known (CHCHD7 and COL3A1) and six were novel (SRSF3, HNRNPC, PCMTD1, YWHAZ, CTDSP2, and PPP2R2A). Twelve cases had follow-up (1-107 months; median 21 months), and no recurrences were reported. Lipoblastomas may occur in older children and adults and may be difficult to recognize due to their predominantly adipocytic or fibrous appearance. Awareness that lipoblastomas may occur in older patients, careful evaluation for foci showing more typical morphologic features, ancillary immunohistochemistry for CD34 and desmin, and molecular genetic studies to identify PLAG1 rearrangements are the keys to recognizing these tumors.

Recent advances in smooth muscle tumors with PGR and PLAG1 gene fusions and myofibroblastic uterine neoplasms

Uterine epithelioid and myxoid leiomyosarcomas and inflammatory myofibroblastic tumors are rare mesenchymal neoplasms. Next-generation sequencing recently detected novel PGR fusions in uterine epithelioid leiomyosarcomas that demonstrate characteristic rhabdoid and spindled morphology. PLAG1 gene fusions have also been identified in a subset of myxoid leiomyosarcomas and are associated with PLAG1 overexpression. ALK rearrangements underpin the vast majority of uterine inflammatory myofibroblastic tumors, which demonstrate morphologic, and immunohistochemical features similar to those of inflammatory myofibroblastic tumors elsewhere. This review summarizes the morphologic, immunophenotypic, and molecular genetic features of PGR fusion-positive epithelioid leiomyosarcoma, PLAG1 fusion-positive myxoid leiomyosarcoma, and inflammatory myofibroblastic tumors of the uterus.

New molecular insights into the pathogenesis of lipoblastomas: clinicopathologic, immunohistochemical, and molecular analysis in pediatric cases

Lipoblastomas can occasionally require further molecular confirmation when occurring outside of the usual age groups or demonstrating unusual morphology. We reviewed 28 lipoblastomas with 16 controls. Lipoblastomas were subdivided into myxoid (n = 7), classic (n = 9), or lipoma-like (n = 12) subtypes. PLAG1 immunohistochemistry, PLAG1 fluorescence in situ hybridization (FISH), and targeted RNA sequencing were performed on formalin-fixed paraffin-embedded tissue. Karyotypes were available in a subset of lipoblastomas (n = 9). Gene rearrangements were identified in 17/25 (68%) lipoblastomas, including PLAG1 (15/25, 60%) and HMGA2 (2/25, 8%). Five novel fusion partners (DDX6, KLF10, and KANSL1L with PLAG1 and EP400 and FGD6 with HMGA2) were found. PLAG1 immunohistochemistry was positive (nuclear, moderate/strong) in myxoid and classic subtypes lipoblastomas with preferential expression in mesenchymal cells within myxoid stroma and fibrous septa and negative in all controls. When comparing PLAG1 immunohistochemistry with molecular testing (FISH and/or RNA sequencing and/or karyotype), concordant results were noted in 13/25 (52%) cases, increasing to 15/25 (60%) after slight adjustment of the PLAG1 FISH positive threshold. In myxoid and classic lipoblastomas, PLAG1 immunohistochemistry seems to be a better surrogate marker for PLAG1 rearrangement, as compared with lipoma-like subtypes. In lipoma-like subtypes, targeted RNA sequencing appears to detect PLAG1 fusions better than FISH and immunohistochemistry. The preferential expression of PLAG1 in the mesenchymal and fibroblast-like cells deserves further investigation as the putative cell of origin in lipoblastoma.

Rapidly Growing Facial Tumor in a 5-Year-Old Girl

The aim of this study is to describe the clinical, radiological and histological characteristics that define lipoblastomas with special emphasis on differential diagnosis. The patient is a 5-year-old girl who consulted for a rapidly growing lower cheek tumor. This study analyzes, evaluates, and discusses the issues that need to be addressed throughout the process that affect treatment planning and provides an updated review of these rare head-and-neck tumors.

Role of CD44 in tumor-initiating cells of salivary gland pleomorphic adenoma: More than a surface biomarker

CD44, a cell-surface glycoprotein, functions as a receptor for hyaluronic acid. Our research group has previously shown that CD44 is a biomarker for the CD44^hi cells (tumor-initiating cells; TICs) in murine salivary gland tumors. However, little is known concerning the biological roles of CD44 in the tumorigenesis of pleomorphic adenoma. The present study is aimed to investigate the effects of CD44 on the proliferation, invasive capability, and apoptosis of TICs in vitro, as well as the tumorigenicity of TICs in vivo. The results demonstrated that knockdown of CD44 attenuated the malignant phenotype of TICs. Furthermore, in vivo xenograft studies indicated that CD44 knockdown inhibited tumorigenesis of pleomorphic adenoma. In addition, neither the CD44^low cells nor the CD44-modified CD44^low cells developed neo-tumors, which indicated that overexpression of CD44 did not enable the CD44^low cells to be transformed into TICs. Taken together, these data demonstrate that CD44 not only acts as a biomarker, but also functions as a key player in the tumor-initiating capacity of TICs. These results shed light on the pathogenesis of salivary gland tumors and provide a potential therapeutic target for treating pleomorphic adenoma.

Novel PLAG1 Gene Rearrangement Distinguishes a Subset of Uterine Myxoid Leiomyosarcoma From Other Uterine Myxoid Mesenchymal Tumors

Genetic alterations in uterine myxoid leiomyosarcoma are unknown. We investigate the clinicopathologic features of 19 uterine tumors previously diagnosed as myxoid leiomyosarcomas in which tumoral RNA was subjected to targeted RNA sequencing. PLAG1, BCOR, BCORL1, HMGA2, and ALK break-apart fluorescence in situ hybridization (FISH) and BCOR, PLAG1, and ALK immunohistochemistry were performed in cases which failed or lacked fusions by sequencing. The diagnosis of myxoid leiomyosarcoma was confirmed in 15 cases after exclusion of 4 tumors with BCOR and ALK rearrangements. These 15 patients presented at a median age of 50 years with stage I (3), II (2), III (2), and IV (1) tumors, respectively; stage was unknown in 7 cases. Tumor size ranged from 10 to 24 cm. Matrix was myxoid in all tumors and also eosinophilic in 2. Cells were spindled, epithelioid, and both in 10, 2, and 3 tumors and showed mild, moderate, and severe nuclear atypia in 3, 8, and 4 tumors, respectively. Mitotic index ranged from <1 to 14/10 HPF, while tumor necrosis was present in 6 (40%). Novel TRPS1-PLAG1 or RAD51B-PLAG1 fusions were detected by sequencing in 4 tumors, 3 of which were also confirmed by FISH. Diffuse PLAG1 expression was seen in 7 tumors, including 4 with PLAG1 rearrangement. No morphologic differences were seen among PLAG1 fusion-positive and fusion-negative tumors. No PLAG1, HMGA2, ALK, BCOR, or BCORL1 rearrangements were detected by FISH in 11 tumors. On the basis of sequencing and FISH results, PLAG1 rearrangements resulting in PLAG1 expression underpin ~25% of myxoid leiomyosarcomas and may serve as a useful diagnostic biomarker. Immunohistochemistry, targeted RNA sequencing, and/or FISH may distinguish myxoid leiomyosarcoma from its morphologic mimics.

Undifferentiated myxoid lipoblastoma with PLAG1 gene rearrangement in infant

OBJECTIVES

To analyze the clinicopathologic feature, diagnosis and differential diagnosis of undifferentiated myxoid lipoblastoma in infant.

METHODS

The study included 2 cases of undifferentiated myxoid lipoblastoma in infant according to the molecular genetic diagnosis. The relevant clinicopathologic feature was investigated.

RESULTS

We describe 2 cases of undifferentiated myxoid lipoblastoma in infant. The both large circumscribed masses are located in deep soft tissue. Unlike most lipoblastoma, lobulated appearance was not obvious in one case and completely absent in another. The both cases presented prominent myxoid change with a plexiform vascular pattern. There were some spindle-shaped or stellate mesenchymal cells, while no any mature adipocytes. The initial suggestion of case 1 was myxoid liposarcoma, and case 2 was aggressive angiomyxoma. However, few S-100 positive lipoblasts suggested the origin of the tumor. FISH analysis using a PLAG1 break apart probe confirmed a PLAG1 rearrangment. The final diagnosis was undifferentiated myxoid lipoblastoma.

CONCLUSIONS

The undifferentiated myxoid lipoblastoma is a very rare tumor in infant. Histologically, prominent myxoid change, a plexiform vascular pattern and lacking of mature adipocytes make it indistinguishable from myxoid liposarcoma, PMMTI and aggressive angiomyxoma. The S-100 positive lipoblasts and genetic rearrangement of PLAG1 helps in confirming the diagnosis. Even if there were no mature adipocytes, myxoid lipoblastoma was still a diagnosis that can not be ignored in myxoid tumors in children.

Three Novel Aberrations Involving PLAG1 Leading to Lipoblastoma in Three Different Patients: High Amplification, Partial Deletion, and a Unique Complex Rearrangement

Lipoblastoma is a rare benign neoplasm with overlapping histology with other lipomatous tumors. Genetic aberrations including translocations of 8q and splitting of the PLAG1 probe leading to "promoter swapping" and gains of chromosome 8 or PLAG1 foci have been described in lipoblastoma. Here, we report 3 lipoblastomas revealing novel genetic aberrations involving PLAG1: a high level of PLAG1 amplification up to 50 copies in a 4-year-old girl with recurrence of a right flank mass, a partial deletion of PLAG1 with the flanking junction breakpoints involving the 3'PLAG1 and 5'HAS2 genes in a 17-month-old boy with a retroperitoneal mass, and an insertion of 2q31 into 8q11.2 and translocation of 8q to 2q with the latter translocated onto 12q leading to separation of the PLAG1 FISH probe in a 5-year-old girl with a left back mass. Our novel cytogenetic findings further expand the mechanisms of PLAG1 transcriptional upregulation in lipoblastoma pathogenesis.

Myxoid Lipoblastoma and Mimickers on Fine-Needle Biopsy in a Child

Image-guided percutaneous core needle biopsy is a standard and safe procedure for the diagnosis of both solid and hematological malignancies in children. Despite recent improvements, nondiagnosis biopsies persist. Lipoblastoma is a benign adipocytic tumor composed of embryonal fat admixed with mature adipocytes and occurring before the age of 1 year in one-third of cases. Lipoblastoma is usually easily diagnosed, but in some cases, diagnosis may be difficult on percutaneous biopsies, when the lipoblastic component is not well represented or when the tumor contains a prominent myxoid component mimicking other myxoid tumors. We report here a case of lipoblastoma with a predominant myxoid component and discuss differential diagnosis of myxoid lesions of infancy. In such cases, pathologic examination enhanced by adjunct techniques, such as immunohistochemistry and cytogenetic or molecular genetic studies, is needed to achieve accurate diagnosis, particularly on fine-needle biopsies.

A contemporary review of myxoid adipocytic tumors

Myxoid adipocytic tumors encompass a broad heterogeneous group of benign and malignant adipocytic tumors, which are typically myxoid (e.g. myxoid liposarcoma, lipoblastoma and lipoblastoma-like tumor of the vulva) or may occasionally appear predominantly myxoid (e.g. pleomorphic liposarcoma, atypical lipomatous tumor, dedifferentiated liposarcoma, chondroid lipoma, spindle cell/pleomorphic lipoma, atypical spindle cell lipomatous tumor and atypical pleomorphic lipomatous tumor). There have been significant advances in recent years in classification and understanding the pathogenesis of adipocytic tumors, based on the correlation of histologic, immunohistochemical, and cytogenetic/molecular findings. Despite these advances, the morphologic diagnosis and accurate classification of a myxoid adipocytic tumor can be challenging due to major morphologic overlap between myxoid adipocytic and non-adipocytic tumors. This article will provide a review on the currently known morphological, immunohistochemical and molecular features of myxoid adipocytic tumors and their differential diagnosis.

Primitive myxoid mesenchymal tumor of infancy with brain metastasis: first reported case

INTRODUCTION

Primitive myxoid mesenchymal tumor of infancy (PMMTI) is a recently diagnosed entity, with only a handful of cases reported to date.

CASE DESCRIPTION

Herein, we present the occurrence of this tumor in a 2-year-old boy, initially diagnosed as primitive neuroectodermal tumor of the extremity and treated with chemotherapy and surgical resection. He later presented with a cerebellar lesion, and biopsy was consistent with PMMTI.

CONCLUSION

While there have been previous cases of PMMTI reported with loco-regional metastatic spread, to our knowledge, there is no known incidence of distant metastasis with involvement of the central nervous system, which makes this case the first of its kind.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Lipoblastoma: a clinicopathologic review of 23 cases from a major tertiary care center plus detailed review of literature

Objective

Lipoblastoma is a rare neoplasm that occurs mostly in infants and children. Although benign, it has a tendency for local recurrence.

Results

Clinical and pathological features of 23 cases of lipoblastoma described. Patients’ age ranged from 8 months to 18 years with mean and median age 4.1 and 2.5 years, respectively. Male:female ratio was 2.8:1. Most common sites were lower extremities (9 cases), followed by abdominal cavity and retroperitoneum (4 cases), and scrotum/groin (3 cases). Grossly, 22 tumors were well circumscribed and multi nodular. All cases showed lobules composed of adipocytes and lipoblasts with intervening fibrous septa and fine vascular network. Myxoid change, capsule formation and septation were seen in all cases. Zonation was seen in 2 cases. Follow-up was available in 14 out of 23 patients. Of these, 13 were alive and free of disease with no evidence of any recurrent lesion. One patient with a mediastinal infiltrating lipoblastoma experienced 4 recurrences. Lipoblastoma is a benign adipocytic neoplasm of infants and young children. Correlation of clinical and histological features helps in reaching a correct diagnosis. Owing to a high recurrence rate following incomplete resection, a complete resection is essential. Prognosis is excellent after complete resection.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3153-8) contains supplementary material, which is available to authorized users.