Serial block-face scanning electron microscopy of the tail tip of post-metamorphic amphioxus finds novel myomeres with odd shapes and unusually prominent sclerocoels.

Serial block-face scanning electron microscopy of the tail tip of post-metamorphic amphioxus (Branchiostoma floridae) revealed some terminal myomeres never been seen before with other techniques. The morphology of these myomeres differed markedly from the chevron shapes of their more anterior counterparts. Histologically, these odd-shaped myomeres ranged from empty vesicles bordered by undifferentiated cells to ventral sacs composed of well-developed myotome, dermatome, and sclerotome. Strikingly, several of these ventral sacs gave rise to a nipple-like dorsal projection composed either entirely of sclerotome or a mixture of sclerotome and myotome. Considered as a whole, from posterior to anterior, these odd-shaped posterior myomeres suggested that their more substantial ventral part may represent the ventral limb of a chevron, while the delicate projection represents a nascent dorsal limb. This scenario contrasts with formation of chevron-shaped myomeres along most of the antero-posterior axis. Although typical chevron formation in amphioxus is surprisingly poorly studied, it seems to be attained by a dorso-ventral extension of the myomere accompanied by the assumption of a V-shape; this is similar to what happens (at least superficially) in developing fishes. Another unusual feature of the odd-shaped posterior myomeres of amphioxus is their especially distended sclerocoels. One possible function for these might be to protect the posterior end of the central nervous system from trauma when the animals burrow into the substratum.

A squash and a squeeze.

Advanced imaging techniques reveal details of the interactions between the two layers of the embryonic midgut that influence its ultimate shape.

Rare Complete Hydatidiform Mole With p57 Expression in Villous Mesenchyme: Case Report and Review of Discordant p57 Expression in Hydatidiform Moles.

Complete hydatidiform mole (CHM) is a premalignant proliferative disease of the placenta characterized by misexpression of imprinted gene products, most notably p57. The majority of CHM exhibit immunohistochemical absence of p57 protein in villous mesenchyme (VM) and cytotrophoblast (CT) and are thus p57 VM/CT concordant. However, some gestations show loss of p57 in only VM or CT, either in all chorionic villi or a subset thereof (VM/CT discordant). Here, we present a rare case of a p57 VM/CT-discordant CHM with diffuse retention of p57 expression in VM but complete absence in CT. Histologically, the case exhibited typical features of CHM including trophoblast hyperplasia and severe nuclear atypia, but was unusual in the presence of gestational membranes identified ultrasonographically and histologically. Ploidy determination by FISH and genotyping by short tandem repeat analyses showed that this was a diploid gestation with variable allelic ratios and with an androgenetic lineage, similar to previously reported p57 VM/CT-discordant cases.

Mesenchymal Tumors of the Pancreas.

This chapter describes the mesenchymal tumors of the pancreas which are of rare occurrence. Mesenchymal tumors of the pancreas may be benign, of intermediate biological potential or malignant. The more commonly occurring mesenchymal tumors of the pancreas are described in this chapter along with their appropriate immunohistochemical workup and differential diagnoses.

In vivo characterization of chick embryo mesoderm by optical coherence tomography-assisted microindentation.

Embryos are growing organisms with highly heterogeneous properties in space and time. Understanding the mechanical properties is a crucial prerequisite for the investigation of morphogenesis. During the last 10 years, new techniques have been developed to evaluate the mechanical properties of biological tissues in vivo. To address this need, we employed a new instrument that, via the combination of micro-indentation with Optical Coherence Tomography (OCT), allows us to determine both, the spatial distribution of mechanical properties of chick embryos, and the structural changes in real-time. We report here the stiffness measurements on the live chicken embryo, from the mesenchymal tailbud to the epithelialized somites. The storage modulus of the mesoderm increases from (176 ± 18) Pa in the tail to (716 ± 117) Pa in the somitic region (mean ± SEM, n = 12). The midline has a mean storage modulus of (947 ± 111) Pa in the caudal (PSM) presomitic mesoderm (mean ± SEM, n = 12), indicating a stiff rod along the body axis, which thereby mechanically supports the surrounding tissue. The difference in stiffness between midline and presomitic mesoderm decreases as the mesoderm forms somites. This study provides an efficient method for the biomechanical characterization of soft biological tissues in vivo and shows that the mechanical properties strongly relate to different morphological features of the investigated regions.

Carinal Resection and Reconstruction for an Obstructing Inflammatory Myofibroblastic Tumor in a Child.

Inflammatory myofibroblastic tumor (IMT) is a rare soft tissue tumor characterized by proliferation of fibroblastic cells associated with an inflammatory infiltrate. Inflammatory myofibroblastic tumors have a predilection for the pediatric population and are usually found in the lung parenchyma but rarely at the carina. They rarely metastasize but can be locally destructive. Surgical resection is the cornerstone of therapy, which results in excellent survival despite risk of local recurrence. We present the case of a nine-year-old girl with an IMT mass at the carina and obstructing the left main stem bronchus, requiring extensive resection and reconstruction.

A challenging diagnosis of mesenchymal neoplasm of the colon: colonic dedifferentiated liposarcoma with lymph node metastases-a case report and review of the literature.

PURPOSE: We report a case of primitive colonic dedifferentiated liposarcoma along with lymph node metastases. METHODS: The patient's clinical, radiologic, surgical, and histologic data were reviewed, as well as the literature on colonic dedifferentiated liposarcoma with a focus on the incidence of lymph node metastasis in gastrointestinal sarcomas and on the differential diagnosis with other spindle cell tumors in the gastrointestinal tract. RESULTS: A 53-year-old man was referred to our hospital with a 3 year-history of pain on the right back that was refractory to drugs. He performed an abdominal computed tomography scan which revealed a colonic wall thickening in the hepatic flexure and a few serosal nodularities. With these findings, the patient underwent an extended right hemicolectomy. On histopathologic examination, it turned out to be a colonic dedifferentiated liposarcoma with lymph node metastases. CONCLUSIONS: The present case was a challenging diagnosis both at presurgical and histopathological level because it strongly mimicked a colonic adenocarcinoma. This was due to non-specific clinical and radiological presentation, to the non-characteristic histologic morphology and to the misleading presence of lymph node metastases. Malignant stromal tumors of the gastrointestinal tract beyond gist are fairly rare entities. Colonic dedifferentiated liposarcoma must be kept in mind and must be considered in the differential diagnosis of gastrointestinal tumors.

Machine Learning with Optical Phase Signatures for Phenotypic Profiling of Cell Lines.

Robust and reproducible profiling of cell lines is essential for phenotypic screening assays. The goals of this study were to determine robust and reproducible optical phase signatures of cell lines for classification with machine learning and to correlate optical phase parameters to motile behavior. Digital holographic microscopy (DHM) reconstructed phase maps of cells from two pairs of cancer and non-cancer cell lines. Seventeen image parameters were extracted from each cell's phase map, used for linear support vector machine learning, and correlated to scratch wound closure and Boyden chamber chemotaxis. The classification accuracy was between 90% and 100% for the six pairwise cell line comparisons. Several phase parameters correlated with wound closure rate and chemotaxis across the four cell lines. The level of cell confluence in culture affected phase parameters in all cell lines tested. Results indicate that optical phase features of cell lines are a robust set of quantitative data of potential utility for phenotypic screening and prediction of motile behavior. © 2019 International Society for Advancement of Cytometry.

Atypical Hepatic Mesenchymal Hamartoma: Histologic Appearance, Immunophenotype, and Molecular Findings.

Hepatic mesenchymal hamartoma is a rare benign neoplasm principally encountered in young children. Its origin is unknown. We report an unusual hepatic mesenchymal hamartoma in a 7-month-old girl, including histopathologic findings, immunophenotype, and karyotype. Chromosomal microarray analysis of tumoral tissue and circulating lymphocytes found 4 copies of a segment at 1q44 and fluorescence in situ hybridization indicated tandem triplication, ascribed to expansion of a paternal tandem duplication. This genetic abnormality may have played a role in pathogenesis.

Unique morphogenetic signatures define mammalian neck muscles and associated connective tissues.

In vertebrates, head and trunk muscles develop from different mesodermal populations and are regulated by distinct genetic networks. Neck muscles at the head-trunk interface remain poorly defined due to their complex morphogenesis and dual mesodermal origins. Here, we use genetically modified mice to establish a 3D model that integrates regulatory genes, cell populations and morphogenetic events that define this transition zone. We show that the evolutionary conserved cucullaris-derived muscles originate from posterior cardiopharyngeal mesoderm, not lateral plate mesoderm, and we define new boundaries for neural crest and mesodermal contributions to neck connective tissue. Furthermore, lineage studies and functional analysis of Tbx1- and Pax3-null mice reveal a unique developmental program for somitic neck muscles that is distinct from that of somitic trunk muscles. Our findings unveil the embryological and developmental requirements underlying tetrapod neck myogenesis and provide a blueprint to investigate how muscle subsets are selectively affected in some human myopathies.

Live tissue antibody injection: A novel method for imaging ECM in limb buds and other tissues.

Understanding the morphogenesis and differentiation of tissues and organs from progenitor fields requires methods to visualize this process. Despite an ever-growing recognition that ECM plays an important role in tissue development, studies of ECM movement, and patterns in live tissue are scarce. Here, we describe a method in which a living limb bud is immunolabeled prior to fixation using fluorescent antibodies that recognize two ECM constituents, fibronectin and fibrillin 2. The results show that undifferentiated mesenchyme in quail embryos can be distinguished from prechondrogenic cellular condensations, in situ, via ECM antibodies-indicating the developmental transition from naïve mesenchyme to committed skeletal tissue. We conclude that our live tissue injection method is a general approach that allows visualization of the structural characteristics and the distribution pattern of ECM scaffolds, in situ. With slight modifications, the method will produce robust fluorescence images of ECM scaffolds in any suitable tissue mass and allow multiple kinds of optical analyses including virtual 3D reconstructions.

The Digestive Tract and Derived Primordia Differentiate by Following a Precise Timeline in Human Embryos Between Carnegie Stages 11 and 13.

The precise mechanisms through which the digestive tract develops during the somite stage remain undefined. In this study, we examined the morphology and precise timeline of differentiation of digestive tract-derived primordia in human somite-stage embryos. We selected 37 human embryos at Carnegie Stage (CS) 11-CS13 (28-33 days after fertilization) and three-dimensionally analyzed the morphology and positioning of the digestive tract and derived primordia in all samples, using images reconstructed from histological serial sections. The digestive tract was initially formed by a narrowing of the yolk sac, and then several derived primordia such as the pharynx, lung, stomach, liver, and dorsal pancreas primordia differentiated during CS12 (21-29 somites) and CS13 (≥ 30 somites). The differentiation of four pairs of pharyngeal pouches was complete in all CS13 embryos. The respiratory primordium was recognized in ≥ 26-somite embryos and it flattened and then branched at CS13. The trachea formed and then elongated in ≥ 35-somite embryos. The stomach adopted a spindle shape in all ≥ 34-somite embryos, and the liver bud was recognized in ≥ 27-somite embryos. The dorsal pancreas appeared as definitive buddings in all but three CS13 embryos, and around these buddings, the small intestine bent in ≥ 33-somite embryos. In ≥ 35-somite embryos, the small intestine rotated around the cranial-caudal axis and had begun to form a primitive intestinal loop, which led to umbilical herniation. These data indicate that the digestive tract and derived primordia differentiate by following a precise timeline and exhibit limited individual variations.

Recurrent malignant sino-nasal solitary fibrous tumor: Eliminate the enemy at the first instance.

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that usually arise in the pleura or less commonly in relation to other serosal surfaces. Infrequent case reports of extra-pleural SFTs have been described at various sub sites within the head and neck area. We report a case of recurrent sino-nasal SFTs treated with surgery followed by re-excision and adjuvant radiation on recurrence and then salvage chemotherapy on progression. Further discussed are the challenges associated with accurate histological and immunohistochemical diagnosis, the difficulty in assessing the aggressiveness and malignant potential of these lesions and the appropriate treatment and follow-up duration that these neoplasms require. To the best of our knowledge this is the first reported case of recurrent malignant sino-nasal SFT in available scientific literature in English language.

Placental mesenchymal dysplasia, a case of intrauterine sudden death.

Placental mesenchymal dysplasia (PMD) is a rare condition presenting with enlarged, multicystic placenta like molar changes. Although PMD usually features a normal fetus and the pregnancy often extends into the third trimester, PMD is clinically significant lesion with high rates of FGR, IUFD, and is associated with Beckwith-Wiedemann syndrome (BWS). We report a 30-year old woman at her first pregnancy with intrauterine sudden death at 31 weeks of gestation. The vesicular lesion in her uterus was detected at 10 weeks on ultrasound. The fetus was normal size without any anomaly on ultrasound and normal trophoblastic vascularization by Doppler study during the pregnancy. As the pregnancy advanced, the vesicular lesion decreased in size and no fetal abnormalities were detected. At 28 weeks of gestation an ultrasound detected dilated periumbilical chorionic vessels. We didn't detect severe FGR or abnormal trophoblastic vascularization. At 31 weeks of gestation an intrauterine sudden death of a normal-sized fetus without any anomaly occurred. The placenta was enlarged, and microscopic morphology confirmed a diagnosis of PMD. The chorionic vessels were cirsoid, dilated and tortuous. We determined the rupture of expanded periumbilical chorionic vessels led to fetal death.

Detection of altered methylation status at 11p15.5 and 7q32 in placental mesenchymal dysplasia.

OBJECTIVE: This paper aims to present molecular cytogenetic and epigenetic evaluation of placental mesenchymal dysplasia (PMD). MATERIALS AND METHODS: A 33-year-old woman was referred to the hospital at 18 weeks of gestation because of a multicystic mass in the placenta. Ultrasound showed a normal amount of amniotic fluid and a normal singleton fetus. Amniocentesis revealed a karyotype of 46,XX. Array comparative genomic hybridization analysis of amniocytes revealed no genomic imbalance. Preterm labor and premature rupture of the membranes occurred, and a female fetus was delivered with no structural abnormality. The placenta was enlarged and filled with many grape-like vesicles. In the placental cystic mass, interphase fluorescence in situ hybridization revealed diploidy and array comparative genomic hybridization revealed no genomic imbalance. Quantitative fluorescent polymerase chain reaction (QF-PCR), methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), and methylation-specific PCR were performed in the placental cystic mass. RESULTS: MS-MLPA analysis showed hypermethylation (methylation index = 0.8) at H19 differentially methylated region (DMR) [imprinting center 1 (IC1)] at 11p15.5 and hypomethylation (methylation index = 0.2) at KvDMR1(IC2) at 11p15.5. Methylation-specific PCR assay identified hypomethylation of PEG1/MEST at 7q32, and hypermethylation at H19DMR and hypomethylation at KvDMR1 at 11p15.5. QF-PCR analysis identified androgenetic/biparental mosaicism in the placenta. The placental cystic mass was consistent with the diagnosis of PMD. CONCLUSION: MS-MLPA and methylation-specific PCR are useful methods for rapid detection of epigenetic alternations in PMD, and QF-PCR is useful in the diagnosis of androgenetic/biparental mosaicism.

Placental mesenchymal dysplasia with hepatic mesenchymal hamartoma: a case report and literature review.

Placental mesenchymal dysplasia (PMD) is characterized by placentomegaly and grapelike vesicles resembling a partial molar pregnancy and in most cases, a phenotypically normal fetus. Hepatic mesenchymal hamartoma (HMH) is a benign hamartomatous proliferation of mesenchymal liver tissue. PMD has been associated with HMH. Although rare, in combination, it is known to carry a poorer prognosis than in fetuses without structural abnormalities. There are only a few reported cases of PMD and associated HMH with varying management strategies and outcomes, precluding ascertainment of the most appropriate treatment plan. We present a case of PMD with associated cystic HMH resulting in fetal death. We also reviewed the published literature on this issue and explored possible management strategies to prevent adverse fetal and neonatal outcomes.

Placental mesenchymal dysplasia: a rare clinicopathologic entity confused with molar pregnancy.

Placental mesenchymal dysplasia (PMD) is a rare placental abnormality characterised by placentomegaly and grape-like vesicles resembling partial mole by ultrasonography, but in contrast to partial mole can co-exist with a viable fetus. Although the karyotype is normal, the fetus is at increased risk for intrauterine growth restriction, intrauterine fetal demise or perinatal death and Beckwith-Wiedemann syndrome. Prenatal diagnosis is difficult and the final diagnosis is usually achieved by postpartum histological examination of the placenta. We present two recent cases of placental mesenchymal dysplasia with poor obstetric outcome. One fetus presented with reduced growth parameters, while the other fetus showed hepatosplenomegaly and early hydropic changes that appear to be associated with Beckwith-Wiedemann syndrome. In this report, the clinico-pathological features of two cases of PMD are discussed and the differentiation from a partial mole is highlighted. This study also supports the utility of cytogenetic ploidy analysis and p57KIP2 protein staining in the evaluation of pregnancies with PMD.

Placental mesenchymal dysplasia: chronological observation of placental images during gestation and review of the literature.

Placental mesenchymal dysplasia (PMD) is characterized by multiple hypoechoic vesicles which are similar to molar changes in the placenta; however, the process of such morphological changes of PMD during pregnancy has not been fully understood. We performed a review of all PMD cases published in English and identified 49 articles including 110 cases. With regard to the gestational age at which the multicystic pattern was seen, approximately 70% of cases were diagnosed at 13-20 weeks of gestation. Another characteristic feature of PMD is varicose dilation of fetal chorionic vessels. As many as 90% of cases were diagnosed as placenta with dilated fetal chorionic vessels in the third trimester. We also report a case of PMD which was found at 10 weeks of gestation according to ultrasonic molar patterns. Serial observations of the placenta using ultrasound and magnetic resonance imaging revealed that multicystic lesions became smaller after 23 weeks. In contrast, dilated placental vessels on the fetal side became apparent at 38 weeks. The present review highlights that placental vesicular lesions of PMD may precede dilation of fetal chorionic vessels during pregnancy. It also indicates the potential of a gradual reduction in size of PMD's placental vesicular lesions by serial study of placental images.

Prenatal and postnatal features of mesenchymal hamartoma of the chest wall: case report and literature review.

Mesenchymal hamartoma of the chest wall is a rare, benign chondro-osseous tumor of the bone. Although it most commonly presents at birth or soon after, prenatal detection is rare. We report a case of prenatally detected mesenchymal hamartoma, and provide the rationale, details, and outcomes of our management. The literature is reviewed, with particular attention to prenatal detection and postnatal management options.