Neurocristopathies: Enigmatic Appearances of Neural Crest Cell-derived Abnormalities.

The neural crest is an important transient structure that develops during embryogenesis in vertebrates. Neural crest cells are multipotent progenitor cells that migrate and develop into a diverse range of cells and tissues throughout the body. Although neural crest cells originate from the ectoderm, they can differentiate into mesodermal-type or endodermal-type cells and tissues. Some of these tissues include the peripheral, autonomic, and enteric nervous systems; chromaffin cells of the adrenal medulla; smooth muscles of the intracranial blood vessels; melanocytes of the skin; cartilage and bones of the face; and parafollicular cells of the thyroid gland. Neurocristopathies are a group of diseases caused by the abnormal generation, migration, or differentiation of neural crest cells. They often involve multiple organ systems in a single person, are often familial, and can be associated with the development of neoplasms. As understanding of the neural crest has advanced, many seemingly disparate diseases, such Treacher Collins syndrome, 22q11.2 deletion syndrome, Hirschsprung disease, neuroblastoma, neurocutaneous melanocytosis, and neurofibromatosis, have come to be recognized as neurocristopathies. Neurocristopathies can be divided into three main categories: dysgenetic malformations, neoplasms, and combined dysgenetic and neoplastic syndromes. In this article, neural crest development, as well as several associated dysgenetic, neoplastic, and combined neurocristopathies, are reviewed. Neurocristopathies often have clinical manifestations in multiple organ systems, and radiologists are positioned to have significant roles in the initial diagnosis of these disorders, evaluation of subclinical associated lesions, creation of treatment plans, and patient follow-up. Online supplemental material is available for this article. ©RSNA, 2019.

Infantile hemangioma: pathogenesis and mechanisms of action of propranolol.

Infantile hemangioma (IH) is the most common benign tumor of childhood, with a prevalence of 4 % to 10 %. It is characterized by a proliferative rapid growth phase, which starts after a few weeks of life, followed by a slow regression phase. In IH cases that are potentially disfiguring or life-threatening (10 % to 15 % of all cases), systemic therapy should be promptly initiated. Data source The present study reviews published scientific articles available in reliable electronic databases. Selected were all studies that evaluated the pathogenesis of IH and the mechanisms of action of propranolol. Conclusions The pathogenesis of IH has not been fully elucidated. Studies show that, in the proliferative phase of IH, there is an imbalance of angiogenic factors and an increase in the levels of vascular endothelial growth factor and matrix metalloproteinases 2 and 9. In the regression phase, the levels of these factors decrease, whereas those of antiangiogenic factors, including tissue inhibitors of matrix metalloproteinases, increase. Since 2008, propranolol has become the drug of choice in the treatment of IH, targeting vascular tone, angiogenesis, and apoptosis. Current insights into the pathogenesis of IH allow for the development of new therapeutic strategies.

Blue Rubber Bleb Nevus Syndrome Diagnosed Prenatally as an Epignathus.

The authors present a clinical report of the giant fetal tumor protruding from the oral cavity diagnosed sonographically at 32 weeks of gestation as an epignathus. After delivery, tumor proved to be a presentation of the blue rubber bleb nevus syndrome. To the best of our knowledge, the literature offers no reports on similar cases.

Infantile hemangiomas exhibit neural crest and pericyte markers.

Infantile hemangiomas (IHs) are the most common benign tumors of infancy and occur with greater than 60% prevalence on the head and neck. Despite their prevalence, little is known about the pathogenesis of this disease. Given the predilection of hemangioma incidence on the face and its nonrandom distribution on embryological fusion plates, we postulated that IHs are derived from pericytes of the neural crest. We performed an analysis on 15 specimens at various stages of the IH progression. Experiments performed included immunohistochemical staining, immunofluorescent staining, quantitative real-time polymerase chain reaction, and flow cytometry. We analyzed a number of cell markers using these methods, including cell markers for the neural crest, pericytes, endothelial cells, stem cells, and the placenta. We observed that neural crest markers such as NG2 and nestin were expressed in the hemangioma samples, in addition tomultiple pericytes markers including δ-like kinase, smooth muscle actin, calponin, and CD90. Stem cell markers such as c-myc, oct4, nanog, and sox2 were also more highly expressed in hemangioma samples compared to controls. Our work demonstrates that hemangiomas express pericyte, neural crest, and stem cell markers suggesting a possible pathogenetic mechanism.

Divided nevus of the eyelid: review of embryology, pathology and treatment.

Divided nevus, which is also known as "kissing nevus," "split ocular nevus" and "panda nevus" is a rare congenital dermatological abnormality that occurs on opposing margins of upper and lower eyelids. There is a paucity of literature on this rare anomaly, with most knowledge from this disease process derived from isolated case reports and series. The purpose of this study is to report a new case of divided nevus of the eyelid and to discuss the unique embryology, pathology, and potential treatment options for this rare entity. A systematic review of literature was performed of the English literature on PubMed and Medline with just under 150 cases reported in the literature. The vast majority of the divided nevi seen in this review were medium sized and of the melanocytic intradermal type. There were no described cases of malignant transformation in any of the documented cases. Numerous methods for reconstruction were described including the entire reconstructive ladder with both one and two staged approaches. In this review, we present basic guidelines to the reconstruction of these complicated defects, although ultimate treatment should be individualized and dependent on surgeon comfort.

Fibroepithelioma of Pinkus is a true basal cell carcinoma developing in association with a newly identified tumour-specific type of epidermal hyperplasia.

BACKGROUND: Fibroepithelioma of Pinkus (FEP) has long been viewed as a subtype of basal cell carcinoma (BCC). Recently, however, the proposal has been made that FEP represents a fenestrated trichoblastoma/trichoepithelioma. One of the main arguments is the presence of Merkel cells in FEP, which typically do not occur in BCC. OBJECTIVES: As the new stem cell marker, PHLDA1 (TDAG51), labels trichoepithelioma but not BCC, our aim was to characterize its staining pattern in FEP. Because adnexal tumours have been viewed as recapitulating embryogenesis, we also examined PHLDA1 immunoreactivity in the skin of human embryos and fetuses. METHODS: We studied immunohistochemically PHLDA1 staining in 31 FEPs, 14 BCCs and 16 trichoepitheliomas and compared this with its staining pattern in embryonic skin and with the distribution of Merkel cells. RESULTS: In FEP, PHLDA1 labels the anastomosing network of thin cellular strands but not the basaloid nubbins. During embryogenesis, PHLDA1 stains the basal cell layer of the epidermis, as long as adnexal structures develop. Immunoreactivity for PHLDA1 correlates positively with the presence of Merkel cells. CONCLUSIONS: We propose that the thin anastomosing network of PHLDA1-positive cells represents a type of epidermal hyperplasia specific to FEP. The multifocal BCCs that are PHLDA1-negative develop from this network which becomes incorporated into the tumour. Viewing the anastomosing network as a tumour-specific form of epidermal hyperplasia explains the hitherto enigmatic presence of Merkel cells in FEP.

Patterns in naevoid skin disease: development, disease and modelling.

The aetiology of pattern-formation in human naevoid skin disease remains unknown. However, it is likely that the majority of previously proposed mechanisms - those that simply rely on passive clonal trafficking in embryogenesis - are incomplete. A more comprehensive explanation for pattern-formation in naevi invokes the principle of self-organization. We define two types of patterning: anatomical and functional. Anatomical patterning is where the abnormal clone is limited to regions of pathologic skin, while functional patterning is where the abnormal clone and pathologic skin are spatially uncorrelated. From a theoretical perspective self-organized naevoid patterns may be either secondary to local interactions between normal and aberrant genotypes or due to the interaction between aberrant genotypes and the presence of normal embryonic patterning cues. The latter possibility suggests the critical observation and analysis of patterns in naevoid skin disease may lead to unique insights into key aspects of early human embryogenesis.

p75 Neurotrophin receptor differentiates between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma: insights into the histogenesis of adnexal tumours based on embryology and hair follicle biology.

BACKGROUND: Tumour development is frequently described in the basic pathology literature as a recapitulation of embryogenesis. However, a link between the embryology of the skin and the histogenesis of adnexal tumours has been largely overlooked. The low-affinity p75 neurotrophin receptor (p75NTR) has a profound role in hair follicle biology. We therefore speculated that it is involved in the histogenesis of follicular adnexal tumours. One of the most challenging diagnoses in dermatopathology is differentiating morphoeic basal cell carcinoma from desmoplastic trichoepithelioma. OBJECTIVES: To describe the expression pattern of p75NTR during cutaneous embryogenesis, in the adult hair follicle and in morphoeic basal cell carcinoma and desmoplastic trichoepithelioma. METHODS: Evaluation of the staining pattern for p75NTR was performed using standard immunohistochemical techniques. For comparison, we examined staining for cytokeratin 20 which highlights Merkel cells. RESULTS: All 17 desmoplastic trichoepitheliomas were immunoreactive with > 80% of the cells stained, whereas 12 of the 14 (86%) morphoeic basal cell carcinomas were p75NTR negative. In the two positive cases of morphoeic basal cell carcinoma < 30% of cells were labelled. In the late bulbous hair peg stage and in the postnatal anagen hair follicle p75NTR highlights the outer root sheath. CONCLUSIONS: Our results support the classification of desmoplastic trichoepithelioma as a follicular hamartoma mimicking the outer root sheath. In contrast, the lack of p75NTR expression in morphoeic basal cell carcinoma favours a concept of this tumour as a more primitive follicular lesion with the characteristics of a carcinoma and not a hamartoma. We suggest including p75NTR as a tool in the differential diagnosis between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma.

Placental anomalies in children with infantile hemangioma.

Evaluation of the placenta provides some important insights into pathophysiologic changes that take place during the prenatal and intrapartum process. We investigated the pathogenic significance of placental features and their relationship to the development of infantile hemangioma in order to obtain a better understanding of its cause. Placental specimens were reviewed from 26 singleton pregnancies of women whose offspring weighed less than 1500 g. A group of 13 neonates who developed infantile hemangioma in the immediate neonate period were compared with 13 healthy preterm infants of comparable postconception age who had no infantile hemangioma. Pathologic placental changes were analyzed in both groups. Gross lesions with disturbance of the utero-placental circulation were found in all placentas from children who developed infantile hemangioma, including massive retroplacental hematoma in two infants, extensive ischemic infarction in seven, and large dilatated vascular communications, severe vasculitis, chorioamnionitis and funiculitis in four. Placental features included percentages greater than 25% of avascular villi, platelet and fibrin aggregates, and multifocal disease involving more than one histologic section. Examination of 13 placentas of low-birth-weight infants without infantile hemangioma only showed abnormal placentation in one and isolated villous dismaturity in two. The higher ratio of placental pathologic findings in patients with infantile hemangioma suggests that reduced placental oxygen diffusive conductance contributes to fetal hypoxic stress and that hypoxic/ischemic changes in the placenta could be related to infantile hemangioma development via vascular endothelial growth factor and placental growth factor expression, among others, within the villious vessels and throphoblasts.

Impact of liver P450 reductase suppression on cyclophosphamide activation, pharmacokinetics and antitumoral activity in a cytochrome P450-based cancer gene therapy model.

The effect of the antithyroid drug methimazole (MMI) on cytochrome P450/P450 reductase-dependent activation of the anti-cancer prodrug cyclophosphamide (CPA) was investigated in a rat model of P450 prodrug activation-based cancer gene therapy. MMI treatment decreased the expression of hepatic P450 reductase by approximately 75% but did not alter P450 reductase levels in a 9L gliosarcoma growing in vivo as a subcutaneous solid tumor. In a pharmacokinetic study, MMI treatment significantly decreased the peak plasma concentration of the active, P450-generated metabolite 4-hydroxy-CPA, from 84.1 to 57.8 microM, and substantially prolonged its apparent half-life, from 25.4 to 54.3 minutes. The area under the plasma concentration x time curve and clearance values for 4-hydroxy-CPA were largely unchanged, however, indicating that MMI decreases the rate but not the overall extent of hepatic CPA activation. MMI alleviated some of the systemic toxicities of CPA treatment, as judged by the moderation of CPA-induced body weight loss and hematuria. The impact of MMI on CPA antitumoral activity was evaluated in rats implanted with 9L tumors transduced with P450 reductase in combination with the CPA-activating P450 2B1, which confers the capacity for intratumoral prodrug activation and leads to markedly enhanced chemosensitivity. CPA given as a single, subtherapeutic dose of 75 mg/kg resulted in a 13.8 day growth delay, whereas CPA in combination with MMI increased the growth delay to 17.4 days. By contrast, a tumor growth delay of only 3.4 days was observed in animals bearing 9L wild-type tumors given the same drug combination. We conclude that the selective reduction of liver P450 reductase after MMI treatment decreases the rate of hepatic drug activation and the host toxicity of CPA without loss of the antitumoral effect, thus increasing the therapeutic index of CPA in a P450-based cancer gene therapy model, where CPA undergoes localized drug activation at its intratumoral site of action.

Pilar neurocristic hamartoma: its relationship to blue nevus and equine melanotic disease.

A unique pigmented lesion, judged to be a hamartoma of neural crest origin, occurring in a female patient, is compared with equine melanotic disease, The characteristic perifollicular arrangement of pigment-laden spindle cells is remarkably similar in both. Previously described patch- and plaque-like blue nevi in humans are also closely related. Light and ultrastructural features showed differentiation toward both nevus cells and Schwann cells, and it is proposed that the lesion be termed pilar neurocristic hamartoma.

Squamous cell carcinoma-like and pox lesions occurring simultaneously in chorioallantoic membranes of chicken embryos inoculated with materials from squamous cell carcinoma and pox lesions in broiler chickens.

The finding of closely associated squamous cell carcinoma (SCC)-like lesions and pox lesions in chorioallantoic membranes (CAMs) inoculated with skin and palate samples taken from broilers is described. The samples were obtained from two broilers coming from different flocks that were not vaccinated against fowl pox. Both birds presented skin lesions, which were diagnosed in one bird as fowl pox, and in the other as SCC. After inoculation of CAMs with fresh tissues from both birds, histologic examination revealed, in all CAMs, lesions that were characteristic of fowl pox together with lesions consistent with those seen in the skin of broilers affected with SCC. This finding was unexpected and may shed some light on the etiology of SCC.

A case of solitary mastocytoma suggesting a divided form of mast cell nevus.

The case of a 10-week-old boy with a solitary mastocytoma is reported. The lesion, noticed at birth, was located in an area extending from the dorsum of the left hand to the proximal phalanx of the ring and little fingers. It appeared as a coin-sized, flattened dome-shaped, round tumor with occasional blistering. The web between the two fingers was free of cutaneous changes. The diagnosis was confirmed by the histological characteristics: a densely mastocytic infiltration into the dermis. The present case of solitary mastocytoma, referred to as "mast cell nevus", is unique because of its previously undescribed divided form.

[Immunohistochemical localization of S-100 protein in granular cell myoblastoma]. / Localización inmunohistoquímica de la proteína S-100 en el mioblastoma de células granulares.

Three cases of granular cell myoblastoma have been studied in order to determine the presence and distribution of the S-100 specific protein in the neoplastic cells, using immunocytochemical staining techniques, through the modified avidin-biotin method. Positive immunostaining was observed in the three cases studied. The comparative study of various control cases histogenetically originating from neuroectoderm (melanoma) and specifically from Schwann cells, as also the presence of strongly positive staining in Schwann cells of peripheral nerve fibres situated inside and outside the tumor, support the concept of the neurogenic origin of this interesting tumor.

Could pericytic mimicry represent another type of melanoma cell plasticity with embryonic properties?

We hypothesize that the interaction between angiotropic melanoma cells and the abluminal vascular surface can induce or sustain embryonic and/or stem cell migratory properties in these tumor cells. As a result, such angiotropic melanoma cells may migrate along the abluminal vascular surface, demonstrating pericytic mimicry. Through these cellular interactions, melanoma cells may migrate toward secondary sites.