Vascular Malformations: A Histopathologic and Conceptual Appraisal / Malformaciones vasculares: un enfoque histopatológico y conceptual

In the field of vascular anomalies, distinguishing between vascular malformations and tumors has become crucial for a correct therapeutic approach. However, the differential diagnosis between these two groups is not always well explained in classical texts, mainly because many vascular malformations are still known with old names that suggest a tumoral nature. Also, genetic and pathogenic knowledge of these entities has greatly increased in recent decades, so researchers and clinicians now have a better understanding of vascular malformations. In this paper, we present the main histopathological tips to recognize and identify a vascular malformation as such. We also contextualize such information in the clinical and pathogenic knowledge for a better understanding of these entities (AU)

En el campo de las anomalías vasculares, distinguir entre malformaciones vasculares y tumores vasculares se ha vuelto esencial para un enfoque terapéutico correcto. Sin embargo, el diagnóstico diferencial entre estos dos grupos no está siempre correctamente explicado en los textos clásicos, principalmente porque a muchas malformaciones vasculares se las conoce todavía con nombres antiguos que sugieren tumores vasculares. Asimismo, el conocimiento genético y patogénico de estas entidades se ha incrementado notablemente en las décadas recientes, de tal manera que investigadores y clínicos tienen ahora una mejor comprensión de las malformaciones vasculares. En este artículo, presentamos las principales claves histopatológicas para reconocer las malformaciones vasculares e identificarlas como tal. También contextualizamos tal información en el conocimiento clínico y patogénico para mejor comprensión de estas entidades (AU)

[Artículo traducido] Malformaciones vasculares: un enfoque histopatológico y conceptual / Vascular Malformations: A Histopathologic and Conceptual Appraisal

En el campo de las anomalías vasculares, distinguir entre malformaciones vasculares y tumores vasculares se ha vuelto esencial para un enfoque terapéutico correcto. Sin embargo, el diagnóstico diferencial entre estos dos grupos no está siempre correctamente explicado en los textos clásicos, principalmente porque a muchas malformaciones vasculares se las conoce todavía con nombres antiguos que sugieren tumores vasculares. Asimismo, el conocimiento genético y patogénico de estas entidades se ha incrementado notablemente en las décadas recientes, de tal manera que investigadores y clínicos tienen ahora una mejor comprensión de las malformaciones vasculares. En este artículo, presentamos las principales claves histopatológicas para reconocer las malformaciones vasculares e identificarlas como tal. También contextualizamos tal información en el conocimiento clínico y patogénico para mejor comprensión de estas entidades (AU)

In the field of vascular anomalies, distinguishing between vascular malformations and tumors has become crucial for a correct therapeutic approach. However, the differential diagnosis between these two groups is not always well explained in classical texts, mainly because many vascular malformations are still known with old names that suggest a tumoral nature. Also, genetic and pathogenic knowledge of these entities has greatly increased in recent decades, so researchers and clinicians now have a better understanding of vascular malformations. In this paper, we present the main histopathological tips to recognize and identify a vascular malformation as such. We also contextualize such information in the clinical and pathogenic knowledge for a better understanding of these entities (AU)

Vascular Malformations: A Histopathologic and Conceptual Appraisal. / [Artículo traducido] Malformaciones vasculares: un enfoque histopatológico y conceptual.

In the field of vascular anomalies, distinguishing between vascular malformations and tumors has become crucial for a correct therapeutic approach. However, the differential diagnosis between these two groups is not always well explained in classical texts, mainly because many vascular malformations are still known with old names that suggest a tumoral nature. Also, genetic and pathogenic knowledge of these entities has greatly increased in recent decades, so researchers and clinicians now have a better understanding of vascular malformations. In this paper, we present the main histopathological tips to recognize and identify a vascular malformation as such. We also contextualize such information in the clinical and pathogenic knowledge for a better understanding of these entities.

Vascular Malformations: A Histopathologic and Conceptual Appraisal.

In the field of vascular anomalies, distinguishing between vascular malformations and tumors has become crucial for a correct therapeutic approach. However, the differential diagnosis between these two groups is not always well explained in classical texts, mainly because many vascular malformations are still known with old names that suggest a tumoral nature. Also, genetic and pathogenic knowledge of these entities has greatly increased in recent decades, so researchers and clinicians now have a better understanding of vascular malformations. In this paper, we present the main histopathological tips to recognize and identify a vascular malformation as such. We also contextualize such information in the clinical and pathogenic knowledge for a better understanding of these entities.

Skin manifestations of COVID-19 in children: Part 3.

The current COVID-19 pandemic is caused by the SARS-CoV-2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS-CoV-2 infection in children differ from those in adults as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID-19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discuss one of the first and most widespread cutaneous manifestations of COVID-19, chilblain-like lesions, and in Part 2 we expanded to other manifestations, including erythema multiforme, urticaria and Kawasaki disease-like inflammatory multisystemic syndrome. In this part of the review, we discuss the histological findings of COVID-19 manifestations, and the testing and management of infected children for both COVID-19 and any other pre-existing conditions.

Skin manifestations of COVID-19 in children: Part 2.

The current COVID-19 pandemic is caused by the SARS-CoV-2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS-CoV-2 infection in children differ from those in adults, as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID-19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discussed one of the first and most widespread cutaneous manifestations of COVID-19, chilblain-like lesions. In this part of the review, we describe other manifestations, including erythema multiforme, urticaria and Kawasaki disease-like inflammatory multisystemic syndrome. In Part 3, we discuss the histological findings of COVID-19 manifestations, and the testing and management of infected children for both COVID-19 and any other pre-existing conditions.

Skin manifestations of COVID-19 in children: Part 1.

The current COVID-19 pandemic is caused by the SARS-CoV-2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS-CoV-2 infection in children differ from those in adults as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID-19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discuss one of the first and most widespread cutaneous manifestation of COVID-19, chilblain-like lesions. In Part 2, we review other manifestations, including erythema multiforme, urticaria and Kawasaki disease-like inflammatory multisystemic syndrome, while in Part 3, we discuss the histological findings of COVID-19 manifestations, and the testing and management of infected children, for both COVID-19 and any other pre-existing conditions.

SARS-CoV-2 Has Not Been Detected Directly by Electron Microscopy in the Endothelium of Chilblain Lesions: reply from authors.

We fully agree that the interpretation of electron microscopy findings can be challenging, even for experts. Differences between viral pathogens and normal subcellular organelles may be subtle, and some cellular components can masquerade as viruses. The size and shape of the particle shown in our paper fit with other descriptions of SARS-CoV-2, but there may be a bias in interpretation.

SARS-CoV-2 endothelial infection causes COVID-19 chilblains: histopathological, immunohistochemical and ultrastructural study of seven paediatric cases.

BACKGROUND: Chilblains ('COVID toes') are being seen with increasing frequency in children and young adults during the COVID-19 pandemic. Detailed histopathological descriptions of COVID-19 chilblains have not been reported, and causality of SARS-CoV-2 has not yet been established. OBJECTIVES: To describe the histopathological features of COVID-19 chilblains and to explore the presence of SARS-CoV-2 in the tissue. METHODS: We examined skin biopsies from seven paediatric patients presenting with chilblains during the COVID-19 pandemic. Immunohistochemistry for SARS-CoV-2 was performed in all cases and electron microscopy in one. RESULTS: Histopathology showed variable degrees of lymphocytic vasculitis ranging from endothelial swelling and endotheliitis to fibrinoid necrosis and thrombosis. Purpura, superficial and deep perivascular lymphocytic inflammation with perieccrine accentuation, oedema, and mild vacuolar interface damage were also seen. SARS-CoV-2 immunohistochemistry was positive in endothelial cells and epithelial cells of eccrine glands. Coronavirus particles were found in the cytoplasm of endothelial cells on electron microscopy. CONCLUSIONS: Although the clinical and histopathological features were similar to other forms of chilblains, the presence of viral particles in the endothelium and the histological evidence of vascular damage support a causal relation of the lesions with SARS-CoV-2. Endothelial damage induced by the virus could be the key mechanism in the pathogenesis of COVID-19 chilblains and perhaps also in a group of patients severely affected by COVID-19 presenting with features of microangiopathic damage. What is already known about this topic? Despite the high number of cases of chilblains seen during the COVID-19 pandemic, a definite causative role for SARS-CoV-2 has not yet been proven. Different pathogenetic hypotheses have been proposed, including coagulation anomalies, interferon release and external factors. What does this study add? The demonstration of SARS-CoV-2 in endothelial cells of skin biopsies by immunohistochemistry and electron microscopy confirms that these lesions are part of the spectrum of COVID-19. Virus-induced vascular damage and secondary ischaemia could explain the pathophysiology of COVID-19 chilblains. Our findings support the hypothesis that widespread endothelial infection by SARS-CoV-2 could have a pathogenetic role in the severe forms of COVID-19. Linked Comment: Wetter. Br J Dermatol 2020; 183:611.

Histopathological hallmarks of cutaneous lesions of capillary malformation-arteriovenous malformation syndrome.

IMPORTANCE: Capillary malformation-arteriovenous malformation (CM-AVM) syndrome is a recently described syndrome with distinctive cutaneous lesions. Very little is known about the histopathology of these lesions. OBJECTIVE: The purpose of the study was to evaluate the histopathological characteristics of the pink macules of the CM-AVM syndrome and to investigate if these pink macules could be classified as capillary malformations or arteriovenous malformations based on their histopathological features. DESIGN-SETTINGS-PARTICIPANTS: We conducted a retrospective multicenter study involving eight hospitals in Spain. Fifteen biopsies from pink macules of the CM-AVM syndrome were analysed and compared with five biopsies of diverse capillary malformations and three stage I arteriovenous malformations. RESULTS: Pink macules' biopsies of the CM-AVM syndrome showed similar features including a high vascular density encompassing capillaries and numerous thick-walled arterioles mainly located in the superficial dermis, a predominance of elongated over round vessels, scarce or absent erythrocytes within the lumina and discrete perivascular inflammation. CMs were characterized by an increased number of capillary-type vessels mostly rounded and located in the upper dermis. AVMs were composed by highly increased numbers of vessels with a branching pattern involving the full thickness of the dermis, without erythrocytes within the lumina. Wilms tumour 1 protein was positive in the endothelial cells both in pink macules of the CM-AVM and in arteriovenous malformations. CONCLUSIONS AND RELEVANCE: Pink macules of the CM-AVM syndrome seem to be different from capillary malformations. Our results suggest that histologically and immunohistochemically they are closer to incipient arteriovenous malformations than to capillary malformations. A deepened knowledge about the nature of these skin lesions will contribute to the better understanding of capillary malformation-arteriovenous malformation syndrome, and will open the possibility of new and more specific treatments in the future.

Nevo de Spitz y otros tumores spitzoides en la infancia. Parte 1: aspectos clínicos, histológicos e inmunohistoquímicos / Spitz Nevus and Other Spitzoid Tumors in Children-Part 1: Clinical, Histopathologic, and Immunohistochemical Features

El nevo de Spitz es una neoplasia melanocítica de células epitelioides o fusiformes que suele aparecer en la infancia. Su naturaleza es benigna, aunque en ocasiones puede mostrar unas características difíciles de distinguir del melanoma. En las últimas décadas se han clasificado las neoplasias melanocíticas spitzoides en 3tipos: nevus de Spitz, tumor de Spitz atípico y melanoma spitzoide. El tumor de Spitz atípico hace referencia a las neoplasias melanocíticas spitzoides que tienen unas características histopatológicas atípicas insuficientes para realizar el diagnóstico de melanoma y cuyo potencial maligno, actualmente, es incierto. Nuestro objetivo es revisar los aspectos clínicos, dermatoscópicos, histopatológicos e inmunohistoquímicos de este conjunto de tumores

A Spitz nevus is a melanocytic neoplasm of epithelioid and/or spindle cells that usually appears in childhood. These lesions are by nature benign, but their features can sometimes make them difficult to distinguish from melanomas. Spitzoid melanocytic lesions have been grouped into 3 types in recent decades: Spitz nevi, atypical Spitz tumors, and spitzoid melanomas. Atypical Spitz tumors are spitzoid melanocytic proliferations that have atypical histopathologic features that are insufficient to support a diagnosis of melanoma. The malignant potential of these lesions is at present uncertain. This review examines the clinical, dermoscopic, and histopathologic features of this group of lesions

Nevo de Spitz y otros tumores spitzoides en la infancia. Parte 2: características citogenéticas y moleculares. Pronóstico y tratamiento / Spitz Nevus and Other Spitzoid Tumors in Children. Part 2: Cytogenetic and Molecular Features. Prognosis and Treatment

Las neoplasias melanocíticas con morfología spitzoide (nevo de Spitz, tumor de Spitz atípico y melanoma spitzoide) abarcan un espectro desde lesiones benignas a malignas. Debido al potencial maligno incierto de los tumores de Spitz atípicos, el abordaje terapéutico ha generado durante años controversia. El desarrollo de nuevas técnicas moleculares parece prometedor y ha contribuido a una mejor predicción del comportamiento biológico de los tumores de Spitz. Nuestro objetivo es revisar las características citogenéticas de los tumores de Spitz, el pronóstico y actualizar las últimas recomendaciones de manejo

Melanocytic neoplasms with spitzoid morphology (Spitz nevi, atypical Spitz tumors, and spitzoid melanomas) may be benign or malignant. Because the malignant potential of atypical Spitz tumors is uncertain, the proper therapeutic approach has been much debated over the years. Promising new techniques for molecular analysis have enabled better predictions of the biological behavior of these tumors. We review their cytogenetic features and prognosis and also provide an update of the most recent recommendations for management

Happle-Tinschert, Curry-Jones and segmental basal cell naevus syndromes, overlapping disorders caused by somatic mutations in hedgehog signalling genes: the mosaic hedgehog spectrum.

Happle-Tinschert syndrome (HTS) and Curry-Jones syndrome (CJS; OMIM 601707) are rare, sporadic, multisystem disorders characterized by hypo- and hyperpigmented skin patches following Blaschko's lines, plus acral skeletal and other abnormalities. The blaschkoid pattern implies mosaicism, and indeed CJS was found in 2016 to be caused by a recurrent postzygotic mutation in a gene of the hedgehog signalling pathway, namely SMO, c.1234C>T, p.Leu412Phe. More recently the original case of HTS was found to carry the same somatic mutation. Despite this genetic and phenotypic overlap, two significant differences remained between the two syndromes. The histological hallmark of HTS, basaloid follicular hamartomas, is not a feature of CJS. Meanwhile, the severe gastrointestinal manifestations regularly reported in CJS had not been described in HTS. We report a patient whose phenotype was entirely consistent with HTS apart from intractable constipation, and a second patient with classic features of CJS plus early-onset medulloblastoma, a feature of basal cell naevus syndrome (BCNS). Both had the same recurrent SMO mutation. This prompted a literature review that revealed a case with the same somatic mutation, with basaloid follicular hamartomas and other features of both CJS and BCNS. Segmental BCNS can also be caused by a somatic mutation in PTCH1. We thus demonstrate for the first time phenotypic and genetic overlap between HTS, CJS and segmental BCNS. All of these conditions are caused by somatic mutations in genes of the hedgehog signalling pathway and we therefore propose the unifying term 'mosaic hedgehog spectrum'. What's already known about this topic? Happle-Tinschert syndrome (HTS) and Curry-Jones syndrome (CJS) are rare mosaic multisystem disorders with linear skin lesions. CJS is characterized by severe constipation, which has not previously been reported in HTS. HTS is characterized by basaloid follicular hamartomas, which are not a recognized feature of CJS. The recurrent mosaic SMO mutation found in CJS was recently reported in a patient with HTS. What does this study add? We describe a patient with HTS and intractable constipation, and a case of CJS with medulloblastoma. Both patients had the same recurrent somatic SMO mutation also found in a case reported as segmental basal cell naevus syndrome. SMO functions in the hedgehog pathway, explaining phenotypic overlap between HTS, CJS and mosaic basal cell naevus syndrome. We propose the term 'mosaic hedgehog spectrum' for these overlapping conditions.

Spitz Nevus and Other Spitzoid Tumors in Children. Part 2: Cytogenetic and Molecular Features. Prognosis and Treatment. / Nevo de Spitz y otros tumores spitzoides en la infancia. Parte 2: características citogenéticas y moleculares. Pronóstico y tratamiento.

Melanocytic neoplasms with spitzoid morphology (Spitz nevi, atypical Spitz tumors, and spitzoid melanomas) may be benign or malignant. Because the malignant potential of atypical Spitz tumors is uncertain, the proper therapeutic approach has been much debated over the years. Promising new techniques for molecular analysis have enabled better predictions of the biological behavior of these tumors. We review their cytogenetic features and prognosis and also provide an update of the most recent recommendations for management.

Spitz Nevus and Other Spitzoid Tumors in Children -Part 1: Clinical, Histopathologic, and Immunohistochemical Features. / Nevo de Spitz y otros tumores spitzoides en la infancia. Parte 1: aspectos clínicos, histológicos e inmunohistoquímicos.

A Spitz nevus is a melanocytic neoplasm of epithelioid and/or spindle cells that usually appears in childhood. These lesions are by nature benign, but their features can sometimes make them difficult to distinguish from melanomas. Spitzoid melanocytic lesions have been grouped into 3 types in recent decades: Spitz nevi, atypical Spitz tumors, and spitzoid melanomas. Atypical Spitz tumors are spitzoid melanocytic proliferations that have atypical histopathologic features that are insufficient to support a diagnosis of melanoma. The malignant potential of these lesions is at present uncertain. This review examines the clinical, dermoscopic, and histopathologic features of this group of lesions.

Cartilage hair hypoplasia with cutaneous lymphomatoid granulomatosis.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive chondrodysplasia characterized by short-stature, sparse hair and impaired cellular immunity. We describe a young girl who was diagnosed with CHH based on the findings of recurrent infections, short stature with metaphyseal chondrodysplasia, and a confirmed bi-allelic RMRP gene mutation. At 13 years, the patient developed an Epstein-Barr virus (EBV)-driven lymphoproliferative disorder involving the lung, which responded partially to chemotherapy. Simultaneously, she developed multiple indurated plaques involving her face, which had histological findings of granulomatous inflammation and EBV-associated low-grade lymphomatoid granulomatosis. The patient received a matched unrelated peripheral blood stem cell transplant at 15 years of age, and her immunological parameters and skin lesions improved. Lymphomatoid forms of granulomatosis and cutaneous EBV-associated malignancies have not been described previously in CHH. This case highlights the possibility of EBV-associated cutaneous malignancy in CHH.

Mosaic NRAS Q61R mutation in a child with giant congenital melanocytic naevus, epidermal naevus syndrome and hypophosphataemic rickets.

The association of hypophosphataemic rickets with verrucous epidermal naevus (EN) and elevated fibroblast growth factor 23 levels is known as cutaneous-skeletal hypophosphataemia syndrome (CSHS), and can be caused by somatic activating mutations in RAS genes. We report a unique patient with CSHS associated with giant congenital melanocytic naevus (CMN), neurocutaneous melanosis and EN syndrome, manifesting as facial linear sebaceous naevus, developmental delay and ocular dermoids. An activating mutation Q61R in the NRAS gene was found in affected skin and ocular tissue but not blood, implying that the disparate manifestations are due to a multilineage activating mutation (mosaic RASopathy). We speculate on the apparently rare association of CSHS with CMN compared with EN. We also report the favourable outcome of this patient at the age of 8 years after extensive neonatal curettage of the giant CMN and use of vitamin D and phosphate supplementation.