Clinical characteristics and surgical management of facial infiltrating lipomatosis: a single center experience

BACKGROUND

Facial infiltrating lipomatosis (FIL) is a rare condition characterized by congenital facial enlargement. Beyond its impact on physical appearance, FIL can also impair essential facial functions such as swallowing, chewing, vision, and breathing, imposing a substantial physiological and psychological burden. Currently, fewer than 80 cases of FIL have been reported, and the characteristics and management strategies for FIL remain unclear.

METHODS

We reviewed the clinical, surgical, and radiological records of 39 FIL patients who were treated at our center. Of these, genetic testing was performed for 21 patients.

RESULTS

Aberrant overgrowth involves subcutaneous fat, bones, muscles, glands, tongue, lips, and teeth. Epidermal nevi could be observed in the dermatomes innervated by the three branches of the trigeminal nerve, with the highest frequency seen in the dermatome of the mandibular branch. Four patients exhibited concurrent hemimegalencephaly (HMEG), with one case presenting HMEG on the opposite side of the FIL. Nineteen patients were confirmed to harbor the PIK3CA mutation. Thirty-three patients underwent surgical procedures, with a post resection recurrence rate of approximately 25%.

CONCLUSIONS

A variety of maxillofacial structures may be involved in FIL. PIK3CA mutations are important pathogenic factors. Emerging targeted therapies could present an additional treatment avenue in the future. However, surgery currently remains the predominant treatment choice for FIL. The timing and modality of surgery should be individually customized, taking into account each patient's unique circumstances. Notably, there is a significant possibility of postoperative recurrence during childhood and adolescence, necessitating early strategic planning of disease management.

Ataluren improves myelopoiesis and neutrophil chemotaxis by restoring ribosome biogenesis and reducing p53 levels in Shwachman-Diamond syndrome cells

Shwachman-Diamond syndrome (SDS) is characterized by neutropenia, exocrine pancreatic insufficiency and skeletal abnormalities. SDS bone marrow haematopoietic progenitors show increased apoptosis and impairment in granulocytic differentiation. Loss of Shwachman-Bodian-Diamond syndrome (SBDS) expression results in reduced eukaryotic 80S ribosome maturation. Biallelic mutations in the SBDS gene are found in ~90% of SDS patients, ~55% of whom carry the c.183-184TA>CT nonsense mutation. Several translational readthrough-inducing drugs aimed at suppressing nonsense mutations have been developed. One of these, ataluren, has received approval in Europe for the treatment of Duchenne muscular dystrophy. We previously showed that ataluren can restore full-length SBDS protein synthesis in SDS-derived bone marrow cells. Here, we extend our preclinical study to assess the functional restoration of SBDS capabilities in vitro and ex vivo. Ataluren improved 80S ribosome assembly and total protein synthesis in SDS-derived cells, restored myelopoiesis in myeloid progenitors, improved neutrophil chemotaxis in vitro and reduced neutrophil dysplastic markers ex vivo. Ataluren also restored full-length SBDS synthesis in primary osteoblasts, suggesting that its beneficial role may go beyond the myeloid compartment. Altogether, our results strengthened the rationale for a Phase I/II clinical trial of ataluren in SDS patients who harbour the nonsense mutation.

Next generation sequencing aids diagnosis and management in a case of encephalocraniocutaneous lipomatosis

Encephalocraniocutaneous lipomatosis (ECCL) is a rare neurocutaneous disorder caused by somatic FGFR1 and KRAS variants. It shares significant phenotypic overlap with several closely related disorders caused by mutations in the RAS-MAPK pathway (mosaic RASopathies). We report a diagnostically challenging case of ECCL in which next-generation sequencing of affected tissue identified a pathologic FGFR1 p.K656E variant, thereby establishing a molecular diagnosis. Patients with FGFR1-associated ECCL carry a risk of developing malignant brain tumors; thus, genetic testing of patients with suspected ECCL has important management implications.

SBDSR126T rescues survival of sbds -/- zebrafish in a dose-dependent manner independently of Tp53

Defects in ribosomal biogenesis profoundly affect organismal development and cellular function, and these ribosomopathies produce a variety of phenotypes. One ribosomopathy, Shwachman-Diamond syndrome (SDS) is characterized by neutropenia, pancreatic exocrine insufficiency, and skeletal anomalies. SDS results from biallelic mutations in SBDS, which encodes a ribosome assembly factor. Some individuals express a missense mutation, SBDS R126T , along with the common K62X mutation. We reported that the sbds-null zebrafish phenocopies much of SDS. We further showed activation of Tp53-dependent pathways before the fish died during the larval stage. Here, we expressed SBDS R126T as a transgene in the sbds -/- background. We showed that one copy of the SBDS R126T transgene permitted the establishment of maternal zygotic sbds-null fish which produced defective embryos with cdkn1a up-regulation, a Tp53 target involved in cell cycle arrest. None survived beyond 3 dpf. However, two copies of the transgene resulted in normal development and lifespan. Surprisingly, neutropenia persisted. The surviving fish displayed suppression of female sex differentiation, a stress response in zebrafish. To evaluate the role of Tp53 in the pathogenesis of sbds -/- fish phenotype, we bred the fish with a DNA binding deficient allele, tp53 M214K Expression of the loss-of-function tp53 M214K did not rescue neutropenia or survival in sbds-null zebrafish. Increased expression of cdkn1a was abrogated in the tp53 M214K/M214K ;sbds -/- fish. We conclude that the amount of SBDSR126T protein is important for development, inactivation of Tp53 fails to rescue neutropenia or survival in the sbds-null background, and cdkn1a up-regulation was dependent on WT tp53 We hypothesize that additional pathways are involved in the pathophysiology of SDS.

Facial infiltrating lipomatosis with hemimegalencephaly and lymphatic malformations caused by nonhotspot phosphatidylinositol 3-kinase catalytic subunit alpha mutation

We report an unusual case of facial infiltrating lipomatosis with hemimegalencephaly and lymphatic malformations. In addition to the clinical data and imaging findings, detection of a heterozygous PIK3CA nonhotspot known pathogenic variant C420R in a facial epidermal nevus provided novel insight into the pathogenic effect of somatic PIK3CA mutations.

Shwachman-Diamond syndromes: clinical, genetic, and biochemical insights from the rare variants

Shwachman-Diamond syndrome is a rare inherited bone marrow failure syndrome characterized by neutropenia, exocrine pancreatic insufficiency, and skeletal abnormalities. In 10-30% of cases, transformation to a myeloid neoplasm occurs. Approximately 90% of patients have biallelic pathogenic variants in the SBDS gene located on human chromosome 7q11. Over the past several years, pathogenic variants in three other genes have been identified to cause similar phenotypes; these are DNAJC21, EFL1, and SRP54. Clinical manifestations involve multiple organ systems and those classically associated with the Shwachman-Diamond syndrome (bone, blood, and pancreas). Neurocognitive, dermatologic, and retinal changes may also be found. There are specific gene-phenotype differences. To date, SBDS, DNAJC21, and SRP54 variants have been associated with myeloid neoplasia. Common to SBDS, EFL1, DNAJC21, and SRP54 is their involvement in ribosome biogenesis or early protein synthesis. These four genes constitute a common biochemical pathway conserved from yeast to humans that involve early stages of protein synthesis and demonstrate the importance of this synthetic pathway in myelopoiesis.

Spectrum of diabetes mellitus in patients with Shwachman-Diamond syndrome: case report and review of the literature

BACKGROUND

Shwachman-Diamond syndrome (SDS) is a rare congenital disorder caused by mutations in the SBDS gene and characterized by exocrine pancreatic deficiency, hematologic dysfunction, and skeletal growth failure. Although the hematologic features and characteristics of the somatic disorders commonly associated with SDS are well known, emerging data from case reports and patient registries suggest that SDS may also be associated with an increased risk of diabetes mellitus. However, currently available data on SDS-associated diabetes are limited and do not allow conclusions regarding prevalence and incidence rates, clinical course, and outcomes.

CASE PRESENTATION

Here we report the case of a 5-year-old girl with SDS who underwent bone marrow transplantation at the age of 3 months and developed autoantibody-positive type 1 diabetes mellitus at the age of 1.8 years. The manifestation and course of diabetes development were mild, complicated by concurrent spontaneous episodes of hypoglycemia even before the onset of antidiabetic treatment. Currently, adequate metabolic control can be achieved by dietary intervention.

CONCLUSIONS

Considering that the SBDS protein regulates mitosis and ribosomal biosynthesis and that its suppression may cause immunologic instability and chronic inflammation, this case provides insight into the phenotype of rare Shwachman-Diamond syndrome-associated diabetes mellitus, which may be characterized by significant age-dependent differences in clinical course.

Delineation of the phenotypes and genotypes of facial infiltrating lipomatosis associated with PIK3CA mutations

BACKGROUND

Facial infiltrating lipomatosis (FIL) is a rare congenital disorder characterized by unilateral facial swelling, for which surgery is the prevailing therapeutic option. Several studies have shown that the development of FIL is closely associated with PIK3CA mutations. This study aimed to further identify rare clinical features and underlying molecular variants in patients with FIL.

RESULTS

Eighteen patients were included in this study, and all patients presented with infiltrating adipose tissues confirmed by magnetic resonance imaging. Macrodactyly, polydactyly, hemimegalencephaly and hemihyperplasia were also observed in patients with FIL. In total, eight different PIK3CA mutations were detected in tissues obtained from sixteen patients, including the missense mutations p.His1047Arg (n = 4), p.Cys420Arg (n = 2), p.Glu453Lys (n = 2), p.Glu542Lys (n = 2), p.Glu418Lys (n = 1), p.Glu545Lys (n = 1), and p.His1047Tyr (n = 1) and the deletion mutation p.Glu110del (n = 3). Furthermore, the GNAQ mutation p.Arg183Gln was detected in the epidermal nevus tissue of one patient. Imaging revealed that several patients carrying hotspot mutations had more severe adipose infiltration and skeletal deformities.

CONCLUSIONS

The abundant clinical presentations and genetic profiles of FIL make it difficult to treat. PIK3CA mutations drive the pathogenesis of FIL, and PIK3CA hotspot mutations may lead to more extensive infiltration of lipomatosis. Understanding the molecular variant profile of FIL will facilitate the application of novel PI3K-targeted inhibitors.

Predisposition to myeloid malignancies in Shwachman-Diamond syndrome: biological insights and clinical advances

Shwachman-Diamond syndrome (SDS) is an inherited multisystem ribosomopathy characterized by exocrine pancreatic deficiency, bone marrow failure, and predisposition to myeloid malignancies. The pathobiology of SDS results from impaired ribosomal maturation due to the deficiency of SBDS and the inability to evict the antiassociation factor eIF6 from the 60S ribosomal subunit. Clinical outcomes for patients with SDS who develop myeloid malignancies are extremely poor because of high treatment-related toxicities and a high rate of refractory disease/relapse even after allogeneic hematopoietic stem cell transplant (HSCT). Registry data indicate that outcomes are improved for patients with SDS who undergo routine bone marrow surveillance and receive an HSCT before developing an overt malignancy. However, the optimal approach to hematologic surveillance and the timing of HSCT for patients with SDS is not clearly established. Recent studies have elucidated distinct patterns of somatic blood mutations in patients with SDS that either alleviate the ribosome defect via somatic rescue (heterozygous EIF6 inactivation) or disrupt cellular checkpoints, resulting in increased leukemogenic potential (heterozygous TP53 inactivation). Genomic analysis revealed that most myeloid malignancies in patients with SDS have biallelic loss-of-function TP53 mutations. Single-cell DNA sequencing of SDS bone marrow samples can detect premalignant biallelic TP53-mutated clones before clinical diagnosis, suggesting that molecular surveillance may enhance the detection of incipient myeloid malignancies when HSCT may be most effective. Here, we review the clinical, genetic, and biologic features of SDS. In addition, we present evidence supporting the hematologic surveillance for patients with SDS that incorporates clinical, pathologic, and molecular data to risk stratify patients and prioritize transplant evaluation for patients with SDS with high-risk features.

PRDM10 directs FLCN expression in a novel disorder overlapping with Birt-Hogg-Dubé syndrome and familial lipomatosis

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant disorder characterized by fibrofolliculomas, pulmonary cysts, pneumothoraces and renal cell carcinomas. Here, we reveal a novel hereditary disorder in a family with skin and mucosal lesions, extensive lipomatosis and renal cell carcinomas. The proband was initially diagnosed with BHD based on the presence of fibrofolliculomas, but no pathogenic germline variant was detected in FLCN, the gene associated with BHD. By whole exome sequencing we identified a heterozygous missense variant (p.(Cys677Tyr)) in a zinc-finger encoding domain of the PRDM10 gene which co-segregated with the phenotype in the family. We show that PRDM10Cys677Tyr loses affinity for a regulatory binding motif in the FLCN promoter, abrogating cellular FLCN mRNA and protein levels. Overexpressing inducible PRDM10Cys677Tyr in renal epithelial cells altered the transcription of multiple genes, showing overlap but also differences with the effects of knocking out FLCN. We propose that PRDM10 controls an extensive gene program and acts as a critical regulator of FLCN gene transcription in human cells. The germline variant PRDM10Cys677Tyr curtails cellular folliculin expression and underlies a distinguishable syndrome characterized by extensive lipomatosis, fibrofolliculomas and renal cell carcinomas.

Shwachman-Diamond Syndrome With Congenital Myogenic Ptosis: Case Report of a Rare Association?

BACKGROUND

Shwachman-Diamond syndrome (SDS) is a multisystem disorder characterized by exocrine pancreatic insufficiency and bone marrow failure. There is considerable variation in the phenotypes of SDS. We present a case of an infant presenting with SDS and left-sided ptosis.

OBSERVATION

We report a case of an infant who presented with 2 episodes of severe sepsis and cytopenia, without overt symptoms of exocrine pancreatic deficiency or skeletal abnormalities. Persistent left-sided ptosis was noted in both presentations. Genetic testing confirmed the diagnosis of SDS. The left-sided ptosis was diagnosed as congenital myogenic ptosis.

CONCLUSION

The association of ptosis and other congenital bone marrow failure syndromes is well established, but this is the first description of SDS with ptosis. This association may expand our understanding of SDS phenotypes if similar cases are reported in the future.

Toward clinical and molecular dissection of frontonasal dysplasia with facial skin polyps: From Pai syndrome to differential diagnosis through a series of 27 patients

Unique or multiple congenital facial skin polyps are features of several rare syndromes, from the most well-known Pai syndrome (PS), to the less recognized oculoauriculofrontonasal syndrome (OAFNS), encephalocraniocutaneous lipomatosis (ECCL), or Sakoda complex (SC). We set up a research project aiming to identify the molecular bases of PS. We reviewed 27 individuals presenting with a syndromic frontonasal polyp and initially referred for PS. Based on strict clinical classification criteria, we could confirm only nine (33%) typical and two (7%) atypical PS individuals. The remaining ones were either OAFNS (11/27-41%) or presenting with an overlapping syndrome (5/27-19%). Because of the phenotypic overlap between these entities, OAFNS, ECCL, and SC can be either considered as differential diagnosis of PS or part of the same spectrum. Exome and/or genome sequencing from blood DNA in 12 patients and from affected tissue in one patient failed to identify any replication in candidate genes. Taken together, our data suggest that conventional approaches routinely utilized for the identification of molecular etiologies responsible for Mendelian disorders are inconclusive. Future studies on affected tissues and multiomics studies will thus be required in order to address either the contribution of mosaic or noncoding variation in these diseases.

What's known and what's new in adipose lesions of peripheral nerves?

BACKGROUND

Adipose lesions of nerve primarily include intra- and extraneural lipomas and lipomatosis of nerve (LN). This paper will summarize the advances that have been made in the past decade, particularly related to LN and nerve territory overgrowth that have improved our understanding of the natural history, genetic background, diagnosis, imaging features, and clinical management.

METHODS AND MATERIALS

Articles about adipose lesions of nerve were reviewed from 2011, when the last comprehensive review on this topic was published. Papers reporting advances on natural history, genetic background, diagnosis, imaging features, and clinical management were screened using PubMed and Google Scholar databases and then analyzed. Case reports and small case series were included only if they reported model examples of discussed pathologies, as these types of articles were summarized in recent systematic reviews on intraneural lipomas and LN. All eligible papers were assessed by the authors, who are subject matter experts.

RESULTS

The first screen revealed 404 articles. After careful evaluation, a total of 53 articles were analyzed which includes advances in diagnosis (especially imaging), classification of the lesions, the role of somatic mutations in PIK3CA in LN, and treatment approaches for all adipose lesions of the peripheral nerve.

CONCLUSION

Many advances have been made in the understanding of adipose lesions of nerve in the past decade. These pathologic entities are more readily recognized as a spectrum of lesions that share common phenotypic features.

Expansion of the phenotypic spectrum and description of molecular findings in a cohort of patients with oculocutaneous mosaic RASopathies

BACKGROUND

Postzygotic KRAS, HRAS, NRAS, and FGFR1 mutations result in a group of mosaic RASopathies characterized by related developmental anomalies in eye, skin, heart, and brain. These oculocutaneous disorders include oculoectodermal syndrome (OES) encephalo-cranio-cutaneous lipomatosis (ECCL), and Schimmelpenning-Feuerstein-Mims syndrome (SFMS). Here, we report the results of the clinical and molecular characterization of a novel cohort of patients with oculocutaneous mosaic RASopathies.

METHODS

Two OES, two ECCL, and two SFMS patients were ascertained in the study. In addition, two subjects with unilateral isolated epibulbar dermoids were also enrolled. Molecular analysis included PCR amplification and Sanger sequencing of KRAS, HRAS, NRAS, and FGFR1 genes in DNA obtained from biopsies (skin/epibulbar dermoids), buccal mucosa, and blood leukocytes. Massive parallel sequencing was employed in two cases with low-level mosaicism.

RESULTS

In DNA from biopsies, mosaicism for pathogenic variants, including KRAS p.Ala146Thr in two OES subjects, FGFR1 p.Asn546Lys and KRAS p.Ala146Val in ECCL patients, and KRAS p.Gly12Asp in both SFMS patients, was demonstrated. No mutations were shown in DNA from conjunctival lesions in two subjects with isolated epibubar dermoids.

CONCLUSION

Our study allowed the expansion of the clinical spectrum of mosaic RASopathies and supports that mosaicism for recurrent mutations in KRAS and FGFR1 is a commonly involved mechanism in these rare oculocutaneous anomalies.

Further evidence for the involvement of EFL1 in a Shwachman-Diamond-like syndrome and expansion of the phenotypic features

Recent evidence has implicated EFL1 in a phenotype overlapping Shwachman-Diamond syndrome (SDS), with the functional interplay between EFL1 and the previously known causative gene SBDS accounting for the similarity in clinical features. Relatively little is known about the phenotypes associated with pathogenic variants in the EFL1 gene, but the initial indication was that phenotypes may be more severe, when compared with SDS. We report a pediatric patient who presented with a metaphyseal dysplasia and was found to have biallelic variants in EFL1 on reanalysis of trio whole-exome sequencing data. The variant had not been initially reported because of the research laboratory's focus on de novo variants. Subsequent phenotyping revealed variability in her manifestations. Although her metaphyseal abnormalities were more severe than in the original reported cohort with EFL1 variants, the bone marrow abnormalities were generally mild, and there was equivocal evidence for pancreatic insufficiency. Despite the limited number of reported patients, variants in EFL1 appear to cause a broader spectrum of symptoms that overlap with those seen in SDS. Our report adds to the evidence of EFL1 being associated with an SDS-like phenotype and provides information adding to our understanding of the phenotypic variability of this disorder. Our report also highlights the value of exome data reanalysis when a diagnosis is not initially apparent.

A unique case of Shwachman-Diamond syndrome presenting with congenital hypopituitarism

Shwachman-Diamond syndrome (SDS) is an autosomal recessive bone marrow failure syndrome typically characterized by neutropenia and pancreatic dysfunction, although phenotypic presentations vary, and the endocrine phenotype is not well-described. We report a unique case of a patient with SDS who initially presented with hypoglycemia and micropenis in the newborn period and was diagnosed with congenital hypopituitarism. We are not aware of any other cases of SDS documented with this combination of complex endocrinopathies.

Evaluation of energy metabolism and calcium homeostasis in cells affected by Shwachman-Diamond syndrome

Isomorphic mutation of the SBDS gene causes Shwachman-Diamond syndrome (SDS). SDS is a rare genetic bone marrow failure and cancer predisposition syndrome. SDS cells have ribosome biogenesis and their protein synthesis altered, which are two high-energy consuming cellular processes. The reported changes in reactive oxygen species production, endoplasmic reticulum stress response and reduced mitochondrial functionality suggest an energy production defect in SDS cells. In our work, we have demonstrated that SDS cells display a Complex IV activity impairment, which causes an oxidative phosphorylation metabolism defect, with a consequent decrease in ATP production. These data were confirmed by an increased glycolytic rate, which compensated for the energetic stress. Moreover, the signalling pathways involved in glycolysis activation also appeared more activated; i.e. we reported AMP-activated protein kinase hyper-phosphorylation. Notably, we also observed an increase in a mammalian target of rapamycin phosphorylation and high intracellular calcium concentration levels ([Ca(2+)]i), which probably represent new biochemical equilibrium modulation in SDS cells. Finally, the SDS cell response to leucine (Leu) was investigated, suggesting its possible use as a therapeutic adjuvant to be tested in clinical trials.

Mosaic Activating Mutations in FGFR1 Cause Encephalocraniocutaneous Lipomatosis

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadic condition characterized by ocular, cutaneous, and central nervous system anomalies. Key clinical features include a well-demarcated hairless fatty nevus on the scalp, benign ocular tumors, and central nervous system lipomas. Seizures, spasticity, and intellectual disability can be present, although affected individuals without seizures and with normal intellect have also been reported. Given the patchy and asymmetric nature of the malformations, ECCL has been hypothesized to be due to a post-zygotic, mosaic mutation. Despite phenotypic overlap with several other disorders associated with mutations in the RAS-MAPK and PI3K-AKT pathways, the molecular etiology of ECCL remains unknown. Using exome sequencing of DNA from multiple affected tissues from five unrelated individuals with ECCL, we identified two mosaic mutations, c.1638C>A (p.Asn546Lys) and c.1966A>G (p.Lys656Glu) within the tyrosine kinase domain of FGFR1, in two affected individuals each. These two residues are the most commonly mutated residues in FGFR1 in human cancers and are associated primarily with CNS tumors. Targeted resequencing of FGFR1 in multiple tissues from an independent cohort of individuals with ECCL identified one additional individual with a c.1638C>A (p.Asn546Lys) mutation in FGFR1. Functional studies of ECCL fibroblast cell lines show increased levels of phosphorylated FGFRs and phosphorylated FRS2, a direct substrate of FGFR1, as well as constitutive activation of RAS-MAPK signaling. In addition to identifying the molecular etiology of ECCL, our results support the emerging overlap between mosaic developmental disorders and tumorigenesis.

Radiosensitivity in lymphoblastoid cell lines derived from Shwachman-Diamond syndrome patients

Shwachman-Diamond syndrome is an autosomal-recessive disorder characterised by bone marrow failure and a cumulative risk of progression to acute myeloid leukaemia. The Shwachman-Bodian-Diamond syndrome (SBDS) gene, the only gene known to be causative of the pathology, is involved in ribosomal biogenesis, stress responses and DNA repair, and the lack of SBDS sensitises cells to many stressors and leads to mitotic spindle destabilisation. The effect of ionising radiation on SBDS-deficient cells was investigated using immortalised lymphocytes from SDS patients in comparison with positive and negative controls in order to test whether, in response to ionising radiation exposure, any impairment in the DNA repair machinery could be observed. After irradiating cells with different doses of X-rays or gamma-rays, DNA repair kinetics and the residual damages using the alkaline COMET assay and the γ-H2AX assay were assessed, respectively. In this work, preliminary data about the comparison between ionising radiation effects in different patients-derived cells and healthy control cells are presented.

In Vivo Senescence in the Sbds-Deficient Murine Pancreas: Cell-Type Specific Consequences of Translation Insufficiency

Genetic models of ribosome dysfunction show selective organ failure, highlighting a gap in our understanding of cell-type specific responses to translation insufficiency. Translation defects underlie a growing list of inherited and acquired cancer-predisposition syndromes referred to as ribosomopathies. We sought to identify molecular mechanisms underlying organ failure in a recessive ribosomopathy, with particular emphasis on the pancreas, an organ with a high and reiterative requirement for protein synthesis. Biallelic loss of function mutations in SBDS are associated with the ribosomopathy Shwachman-Diamond syndrome, which is typified by pancreatic dysfunction, bone marrow failure, skeletal abnormalities and neurological phenotypes. Targeted disruption of Sbds in the murine pancreas resulted in p53 stabilization early in the postnatal period, specifically in acinar cells. Decreased Myc expression was observed and atrophy of the adult SDS pancreas could be explained by the senescence of acinar cells, characterized by induction of Tgfβ, p15^Ink4b and components of the senescence-associated secretory program. This is the first report of senescence, a tumour suppression mechanism, in association with SDS or in response to a ribosomopathy. Genetic ablation of p53 largely resolved digestive enzyme synthesis and acinar compartment hypoplasia, but resulted in decreased cell size, a hallmark of decreased translation capacity. Moreover, p53 ablation resulted in expression of acinar dedifferentiation markers and extensive apoptosis. Our findings indicate a protective role for p53 and senescence in response to Sbds ablation in the pancreas. In contrast to the pancreas, the Tgfβ molecular signature was not detected in fetal bone marrow, liver or brain of mouse models with constitutive Sbds ablation. Nevertheless, as observed with the adult pancreas phenotype, disease phenotypes of embryonic tissues, including marked neuronal cell death due to apoptosis, were determined to be p53-dependent. Our findings therefore point to cell/tissue-specific responses to p53-activation that include distinction between apoptosis and senescence pathways, in the context of translation disruption.

Growth of all living things relies on protein synthesis. Failure of components of the complex protein synthesis machinery underlies a growing list of inherited and acquired multi—organ syndromes referred to as ribosomopathies. While ribosomes, the critical working components of the protein synthesis machinery, are required in all cell types to translate the genetic code, only certain organs manifest clinical symptoms in ribosomopathies, indicating specific cell-type features of protein synthesis control. Further, many of these diseases result in cancer despite an inherent deficit in growth. Here we report a range of consequences of protein synthesis insufficiency with loss of a broadly expressed ribosome factor, leading to growth impairment and cell cycle arrest at different stages. Apparent induction of p53-dependent cell death and arrest pathways included apoptosis in the fetal brain and senescence in the mature exocrine pancreas. The senescence, considered a tumour suppression mechanism, was accompanied by the expression of biomarkers associated with early stages of malignant transformation. These findings inform how cancer may initiate when growth is compromised and provide new insights into cell-type specific consequences of protein synthesis insufficiency.

Loss of mitochondrial SDHB expression: what is its role in diffuse thyroid lipomatosis?

Diffuse lipomatosis of the thyroid gland is a very rare disease, characterized by extensive infiltration of thyroid parenchyma by mature adipose tissue, usually not accompanied by amyloid fibrils deposition. The pathophysiology of adipose tissue infiltration in the thyroid gland remains unknown. We report a clinical case of a diffuse thyroid lipomatosis, whose immunohistochemical study of succinate dehydrogenase - subunit B (SDHB) revealed loss of expression of this protein in the follicular or adipose cells. We detected the presence of a recently described SDHB gene large deletion. Loss of mitochondrial SDHB expression may have a key role in understanding the pathophysiology of thyrolipomatosis, by regulating status of lipid metabolism.

Lipomatous myofibroblastoma of the breast: case report with diagnostic and histogenetic considerations

We report rare case of myofibroblastoma (MFB) of the breast comprised predominantly of a mature fatty component, representing approximately 70% of the entire tumour area. This tumour, designated "lipomatous MFB", should be interpreted as the morphological result of an unbalanced bidirectional differentiation of the precursor mammary stromal cell, with the adipocytic component overwhelming the fibroblastic/myofibroblastic one. Lipomatous MFB is a rare variant of mammary MFB, which can mimic malignancy because of the close juxtaposition of fibroblasts/myofibroblasts with mature adipocytes, resulting in a finger-like infiltrative growth pattern of the former towards the latter. Histogenetic considerations and differential diagnostic problems with other bland-looking spindle cell tumours containing infiltrating fat are provided.

Ribosomal protein mutations induce autophagy through S6 kinase inhibition of the insulin pathway

Mutations affecting the ribosome lead to several diseases known as ribosomopathies, with phenotypes that include growth defects, cytopenia, and bone marrow failure. Diamond-Blackfan anemia (DBA), for example, is a pure red cell aplasia linked to the mutation of ribosomal protein (RP) genes. Here we show the knock-down of the DBA-linked RPS19 gene induces the cellular self-digestion process of autophagy, a pathway critical for proper hematopoiesis. We also observe an increase of autophagy in cells derived from DBA patients, in CD34⁺ erythrocyte progenitor cells with RPS19 knock down, in the red blood cells of zebrafish embryos with RP-deficiency, and in cells from patients with Shwachman-Diamond syndrome (SDS). The loss of RPs in all these models results in a marked increase in S6 kinase phosphorylation that we find is triggered by an increase in reactive oxygen species (ROS). We show that this increase in S6 kinase phosphorylation inhibits the insulin pathway and AKT phosphorylation activity through a mechanism reminiscent of insulin resistance. While stimulating RP-deficient cells with insulin reduces autophagy, antioxidant treatment reduces S6 kinase phosphorylation, autophagy, and stabilization of the p53 tumor suppressor. Our data suggest that RP loss promotes the aberrant activation of both S6 kinase and p53 by increasing intracellular ROS levels. The deregulation of these signaling pathways is likely playing a major role in the pathophysiology of ribosomopathies.

Diseases linked to mutations affecting the ribosome, ribosomopathies, have an exceptionally wide range of phenotypes. However, many ribosomopathies have some features in common including cytopenia and growth defects. Our study aims to clarify the mechanisms behind these common phenotypes. We find that mutations in ribosomal protein genes result in a series of aberrant signaling events that cause cells to start recycling and consuming their own intracellular contents. This basic mechanism of catabolism is activated when cells are starving for nutrients, and also during the tightly regulated process of blood cell maturation. The deregulation of this mechanism provides an explanation as to why blood cells are so acutely affected by mutations in genes that impair the ribosome. Moreover, we find that the signals activating this catabolism are coupled to impairment of the highly conserved insulin-signaling pathway that is essential for growth. Taken together, our in-depth description of the pathways involved as the result of mutations affecting the ribosome increases our understanding about the etiology of these diseases and opens up previously unknown avenues of potential treatment.

[Shwachman-Diamond syndrome]

Shwachman-Diamond syndrome is an inherited autosomal recessive disease that appears as exocrine pancreatic insufficiency, neutropenia, impaired neutrophil chemotaxis, aplastic anemia, thrombocytopenia, metaphyseal dysplasia, and physical retardation. Its worldwide prevalence is 1:10,000 to 1:20,000 live births depending on the region. The SBDS gene and a few mutations, which lead to this syndrome, have been found in the past decade. The paper describes a case of this rare disease in a 28-year-old male patient who has all characteristic manifestations as lipomatosis and severe exocrine pancreatic insufficiency, neutropenia with bone marrow hypoplasia, physical retardation, glucose intolerance, secondary osteopenia, and minor cardiac anomalies. Its clinical diagnosis was verified by molecular genetic testing.

[Two cases of Shwachman-Diamond syndrome with genetic confirmation and literature review]

OBJECTIVE

To study clinical features and gene mutations in Shwachman-Diamond syndrome (SDS), a rare autosomal recessive disease, in children.

METHOD

Clinical manifestations, laboratory examinations, image studies, and genetic testing of two cases with SDS were presented, analyzed, and discussed; 311 SDS cases from the related literature since 2004 were reviewed.

RESULT

(1) The two cases both presented with characteristic exocrine pancreatic insufficiency evidenced by abnormal pancreas on imaging and growth retardation, persistent or intermittent neutropenia (<1500×10(6)/L) and/or anemia, and skeletal abnormalities. Analysis of the SBDS gene revealed the same compound heterozygous genotype (c.183_184TA > CT, c.258+2T > C) for both subjects. This genotype is the result of the inheritance of abnormal alleles from both healthy parents. (2) Among 311 cases, 75 cases having complete clinical data were characterized by exocrine pancreatic dysfunction (61/75; 81.3%), hematologic abnormalities with single- or multi-lineage cytopenia (64/75; 85.3%), and bone abnormalities (47/75; 62.7%). c.183_184TA > CT, c.258+2T > C, and c. [ 183_184TA > CT; 258+2T > C] are the major types of SBDS gene mutation(85/138;61.6%).

CONCLUSION

SDS is characterized by exocrine pancreatic dysfunction with malabsorption, malnutrition, and growth failure; hematologic abnormalities with single- or multi-lineage cytopenia, and bone abnormalities. The diagnosis of SDS relies on a combination of clinical features and gene-based tests. The SDS patients need long term follow-up and management.

The model organism Dictyostelium discoideum

Much of our knowledge of molecular cellular functions is based on studies with a few number of model organisms that were established during the last 50 years. The social amoeba Dictyostelium discoideum is one such model, and has been particularly useful for the study of cell motility, chemotaxis, phagocytosis, endocytic vesicle traffic, cell adhesion, pattern formation, caspase-independent cell death, and, more recently, autophagy and social evolution. As nonmammalian model of human diseases D. discoideum is a newcomer, yet it has proven to be a powerful genetic and cellular model for investigating host-pathogen interactions and microbial infections, for mitochondrial diseases, and for pharmacogenetic studies. The D. discoideum genome harbors several homologs of human genes responsible for a variety of diseases, -including Chediak-Higashi syndrome, lissencephaly, mucolipidosis, Huntington disease, IBMPFD, and Shwachman-Diamond syndrome. A few genes have already been studied, providing new insights on the mechanism of action of the encoded proteins and in some cases on the defect underlying the disease. The opportunities offered by the organism and its place among the nonmammalian models for human diseases will be discussed.

The role of pancreatic imaging in monogenic diabetes mellitus

In neonatal diabetes mellitus resulting from mutations in EIF2AK3, PTF1A, HNF1B, PDX1 or RFX6, pancreatic aplasia or hypoplasia is typical. In maturity-onset diabetes mellitus of the young (MODY), mutations in HNF1B result in aplasia of pancreatic body and tail, and mutations in CEL lead to lipomatosis. The pancreas is not readily accessible for histopathological investigations and pancreatic imaging might, therefore, prove important for diagnosis, treatment, and research into these β-cell diseases. Advanced imaging techniques can identify the pancreatic features that are characteristic of inherited diabetes subtypes, including alterations in organ size (diffuse atrophy and complete or partial pancreatic agenesis), lipomatosis and calcifications. Consequently, in patients with suspected monogenic diabetes mellitus, the results of pancreatic imaging could help guide the molecular and genetic investigation. Imaging findings also highlight the critical roles of specific genes in normal pancreatic development and differentiation and provide new insight into alterations in pancreatic structure that are relevant for β-cell disease.

[Lipoblastoma and lipoblastomatosis: especially in children]

Lipoblastoma and lipoblastomatosis are rare benign fatty tumours that mainly occur in children under the age of 3 years. Several body sites can be affected. The term 'lipoblastoma' is reserved for an encapsulated neoplasm; 'lipoblastomatosis' for tumours demonstrating infiltrative growth. Most of the clinical symptoms arise from a mass effect of the tumour on surrounding tissues. The tumours should be differentiated from lipoma, myxoid liposarcoma and hibernoma. A clear distinction can be made by cytogenetic analysis, since each of these tumours is known for its own typical genetic abnormalities. In lipoblastoma and lipoblastomatosis, these include a breakpoint in the 8q11-13 region or polysomy of chromosome 8, both leading to the activation of the oncogenic pleomorphic adenoma gene 1 (PLAG1) on 8q12. Treatment consists of surgical resection; there is no need for radiotherapy or chemotherapy. Clinical outcome depends on the completeness of the resection and damage that is done to the surrounding tissues during surgery.

Familial angiolipomatosis

Large subcutaneous angiolipomata were observed bilaterally around the wrists, knees, and ankles in an adolescent boy. Growth had been slow since first noted at age 1 year. The tumors extended deeply between muscles, tendons and joint capsules, but without infiltration of these structures. The tumors recurred after subtotal excision. Muscular hypotrophy and deformation of bones near the affected joints were noted. An 8-year-old sister had similar tumors, suggesting a genetic etiology.

Segmental overgrowth, lipomatosis, arteriovenous malformation and epidermal nevus (SOLAMEN) syndrome is related to mosaic PTEN nullizygosity

We describe two patients from distinct Cowden disease families with specific germline PTEN mutations whose disease differs from the usual appearance of Cowden disease. Their phenotype associates classical manifestations of Cowden disease and congenital dysmorphisms including segmental overgrowth, arteriovenous and lymphatic vascular malformations, lipomatosis and linear epidermal nevus reminiscent of the diagnosis of Proteus syndrome. We provide evidence in one of the two patients of a secondary molecular event: a loss of the PTEN wild-type allele, restricted to the atypical lesions that may explain an overgrowth of the affected tissues and the atypical phenotype. These data provide a new demonstration of the Happle hypothesis to explain some segmental exacerbation of autosomal-dominant disorders. They also show that a bi-allelic inactivation of PTEN can lead to developmental anomalies instead of malignant transformation, thus raising the question of the limitations of the tumor suppressive function in this gene. Finally, we suggest using the term 'SOLAMEN syndrome' (Segmental Overgrowth, Lipomatosis, Arteriovenous Malformation and Epidermal Nevus) in these peculiar situations to help the difficult distinction between the phenotype of our patients and Proteus syndrome.

Familial multiple lipomatosis: report of a new family

Familial multiple lipomatosis (FML) is a rare entity. We report a family with this disease. Karyotypic analysis was performed on tissue isolated from excised lipomas and peripheral blood. No chromosomal abnormalities were found. This is the first report of karyotypic analysis of lipomas removed from a patient with FML. The finding of a normal karyotype is important because approximately 25% of spontaneous lipomas will have abnormal karyotypes; therefore, we felt there was a significant probability that familial lipomas in FML would have abnormal karyotypes.

Pancreatic lipomatosis is a structural marker in nondiabetic children with mutations in carboxyl-ester lipase

Both pancreatic volume reduction and lipomatosis have been observed in subjects with diabetes. The underlying molecular and pathological mechanisms are, however, poorly known, and it has been speculated that both features are secondary to diabetes. We have recently described pancreatic atrophy and lipomatosis in diabetic subjects of two Norwegian families with a novel syndrome of diabetes and exocrine pancreatic dysfunction caused by heterozygous carboxyl-ester lipase (CEL) mutations. To explore the early pathological events in this syndrome, we performed radiological examinations of the pancreas in nondiabetic mutation carriers with signs of exocrine dysfunction. In a case series study at a tertiary hospital, we evaluated 11 nondiabetic and mutation-positive children with fecal elastase deficiency and 11 age- and sex-matched control subjects using ultrasound and magnetic resonance imaging (MRI) to estimate pancreatic fat content. The pancreata of nondiabetic mutation carriers exhibited increased reflectivity on ultrasound and had MRI findings indicative of lipomatosis. Apparently, carriers of heterozygous CEL mutations accumulate fat in their pancreas before the anticipated development of diabetes. Our findings suggest that lipomatosis of the pancreas reflects early events involved in the pathogenesis of diabetes and exocrine pancreatic dysfunction syndrome.

Primary cilia deletion in pancreatic epithelial cells results in cyst formation and pancreatitis

BACKGROUND & AIMS

Defects in cilia formation or function have been implicated in several human genetic diseases, including polycystic kidney disease (PKD), Bardet-Biedl syndrome, and primary ciliary dyskinesia. Pancreatic lesions are found in approximately 10% of PKD patients, suggesting a connection between cilia defects and pancreatic pathologies. Here, we investigate the role of cilia in pancreas formation and function by analyzing mice that lack cilia in pancreatic cells.

METHODS

Using Cre/lox technology, we conditionally inactivated Kif3a, the gene encoding for a subunit of the kinesin-2 complex that is essential for cilia formation, in pancreatic epithelia. Kif3a mice were studied by immunohistochemical and biochemical methods to assess the morphology and differentiation status of pancreatic cells.

RESULTS

Tissue-specific loss of Kif3a in pancreatic cells resulted in severe pancreatic abnormalities including acinar-to-ductal metaplasia, fibrosis, and lipomatosis. Ductal metaplasia appears to be due to expansion of ductal cells rather than transdifferentiation of acinar cells. Cyst formation, aberrant ductal morphology, and extensive fibrosis associated with severe adhesion to adjacent organs were commonly observed in aged Kif3a mutant mice. Deletion of Kif3a using different pancreas-specific Cre strains suggests that these pancreatic phenotypes might be caused by the absence of cilia in ductal cells. Activation of transforming growth factor beta and Mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) pathways may play a role in these phenotypes.

CONCLUSIONS

These results demonstrate that the absence of cilia in pancreatic cells produces pancreatic lesions that resemble those found in patients with chronic pancreatitis or cystic fibrosis.

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.

[Myopathy-lipomatosis associated with A8344G mitochondrial DNA mutation]

We report the clinical features of two unrelated patients, a 51-year-old woman and a 54-year-old man, presenting proximal myopathy with lipomatosis. In both patients, muscle biopsies showed numerous ragged-red fibers. Molecular analysis were performed with denaturating gradient gel electrophoresis (DGGE) on muscle, blood, hair, buccal and urinary cells. The A8344G mutation of the tRNA-lysine gene of the mitochondrial DNA was detected in all tissues at high levels (more than 80 p cent). None of the patients had a contributive family history, and signs of central nervous system involvement were absent. These observations confirm that lipomatosis may be encountered in mitochondrial disorders and is tightly associated with the A8344G mutation.