Tumores de colisión en la piel: un hallazgo incidental en la mayoría de los casos. Estudio retrospectivo y revisión de la literatura / Collision tumours in skin: usually an incidental finding. A retrospective study with literature revision

Se denomina tumor de colisión (TC) a la coexistencia de dos o más neoplasias independientes en la misma resección. Suelen ser hallazgos incidentales en la piel, de patogénesis y prevalencia desconocidas, con pocas referencias en la literatura. Aquí mostramos un estudio retrospectivo de TC diagnosticados por un dermatopatólogo entre los años 2019-2022 en nuestro centro. Se han definido las lesiones de manera independiente y organizado cada colisión en categorías: benigno-benigno (BB), benigno-maligno (BM) y maligno-maligno (MM). Del total de 108 TC (1,4% de las biopsias totales del dermatopatólogo en ese periodo), se detecta que la colisión más frecuente es la formada entre BM (48,5%), con un carcinoma basocelular (CBC) como lesión maligna más frecuente de forma global y con un nevus melanocítico (NM) como lesión benigna principal. Se ha realizado el análisis estadístico de los resultados con el software Stata 14.2, detectando una diferencia estadísticamente significativa entre edad y tipo de colisión. (AU)

A collision tumour (CT) is a neoplastic lesion comprised of two or more distinct cell populations that maintain distinct borders. Mostly, these are incidental findings in skin biopsies, whose pathologic mechanism and prevalence remain unknown, with few references among literature. Here, we present a retrospective study of CT, diagnosed by a dermatopathologist in our hospital between 2019-2022. Lesions have been defined individually and organized into three categories: benign-benign (BB), benign-malignant (BM) and malignant-malignant (MM). A total of 108 CT were diagnosed (1,4% of the biopsies from the dermatopathologist during this period), from which BM was the most frequent collision (48,5%). Globally, basal cell carcinoma (BCC) was the main malignant lesion and melanocytic nevus (MN) the main benign lesion. We have used the software Stata 14.2 in order to analyse results, and we have detected a statistically significant difference between age and collision type. (AU)

Tumores de colisión en la piel: un hallazgo incidental en la mayoría de los casos. Estudio retrospectivo y revisión de la literatura / Collision tumours in skin: usually an incidental finding. A retrospective study with literature revision

Se denomina tumor de colisión (TC) a la coexistencia de dos o más neoplasias independientes en la misma resección. Suelen ser hallazgos incidentales en la piel, de patogénesis y prevalencia desconocidas, con pocas referencias en la literatura. Aquí mostramos un estudio retrospectivo de TC diagnosticados por un dermatopatólogo entre los años 2019-2022 en nuestro centro. Se han definido las lesiones de manera independiente y organizado cada colisión en categorías: benigno-benigno (BB), benigno-maligno (BM) y maligno-maligno (MM). Del total de 108 TC (1,4% de las biopsias totales del dermatopatólogo en ese periodo), se detecta que la colisión más frecuente es la formada entre BM (48,5%), con un carcinoma basocelular (CBC) como lesión maligna más frecuente de forma global y con un nevus melanocítico (NM) como lesión benigna principal. Se ha realizado el análisis estadístico de los resultados con el software Stata 14.2, detectando una diferencia estadísticamente significativa entre edad y tipo de colisión. (AU)

A collision tumour (CT) is a neoplastic lesion comprised of two or more distinct cell populations that maintain distinct borders. Mostly, these are incidental findings in skin biopsies, whose pathologic mechanism and prevalence remain unknown, with few references among literature. Here, we present a retrospective study of CT, diagnosed by a dermatopathologist in our hospital between 2019-2022. Lesions have been defined individually and organized into three categories: benign-benign (BB), benign-malignant (BM) and malignant-malignant (MM). A total of 108 CT were diagnosed (1,4% of the biopsies from the dermatopathologist during this period), from which BM was the most frequent collision (48,5%). Globally, basal cell carcinoma (BCC) was the main malignant lesion and melanocytic nevus (MN) the main benign lesion. We have used the software Stata 14.2 in order to analyse results, and we have detected a statistically significant difference between age and collision type. (AU)

[Collision tumours in skin: usually an incidental finding. A retrospective study with literature revision]. / Tumores de colisión en la piel: un hallazgo incidental en la mayoría de los casos. Estudio retrospectivo y revisión de la literatura.

A collision tumour (CT) is a neoplastic lesion comprised of two or more distinct cell populations that maintain distinct borders. Mostly, these are incidental findings in skin biopsies, whose pathologic mechanism and prevalence remain unknown, with few references among literature. Here, we present a retrospective study of CT, diagnosed by a dermatopathologist in our hospital between 2019-2022. Lesions have been defined individually and organized into three categories: benign-benign (BB), benign-malignant (BM) and malignant-malignant (MM). A total of 108 CT were diagnosed (1,4% of the biopsies from the dermatopathologist during this period), from which BM was the most frequent collision (48,5%). Globally, basal cell carcinoma (BCC) was the main malignant lesion and melanocytic nevus (MN) the main benign lesion. We have used the software Stata 14.2 in order to analyse results, and we have detected a statistically significant difference between age and collision type.

Conceptos modernos en tumores melanocíticos / Modern Concepts in Melanocytic Tumors

Con el desarrollo de la enfermedad molecular, el diagnóstico y la comprensión de los tumores melanocíticos ha experimentado un avance descomunal en los últimos años. Esto ha significado la aparición de conceptos de difícil asimilación en el mundo clínico, el cual no está siempre en contacto directo con las técnicas genéticas de laboratorio. Al mismo tiempo, sin embargo, al clínico se le está exigiendo una terapéutica basada en muchas ocasiones en los hallazgos moleculares más recientes de un tumor melanocítico. El presente artículo explora los conceptos moleculares más recientes de la clasificación en rutas patogénicas de los tumores melanocíticos, incluidas las formas intermedias conocidas como melanocitomas, y repasa las técnicas auxiliares usadas en el estudio de estos tumores, discutiendo los resultados más complejos, sus limitaciones, y sus solapamientos (AU)

The advent of molecular pathology has fueled unprecedented advances in the diagnosis and understanding of melanocytic tumors. These advances, however, have also generated concepts that may be difficult to grasp for clinical practitioners, who are not always conversant with the array of genetic techniques employed in the laboratory. These same practitioners, however, are being increasingly called on to provide treatments that are often based on the latest molecular findings for melanocytic tumors. We review the most recent concepts in the pathway classification of melanocytic tumors, including intermediate lesions known as melanocytomas. We examine the genetic and molecular techniques used to study these tumors, look at where they overlap, and discuss their limitations and some of the most difficult-to-interpret results (AU)

[Translated article] Modern Concepts in Melanocytic Tumors / Conceptos modernos en tumores melanocíticos

The advent of molecular pathology has fueled unprecedented advances in the diagnosis and understanding of melanocytic tumors. These advances, however, have also generated concepts that may be difficult to grasp for clinical practitioners, who are not always conversant with the array of genetic techniques employed in the laboratory. These same practitioners, however, are being increasingly called on to provide treatments that are often based on the latest molecular findings for melanocytic tumors. We review the most recent concepts in the pathway classification of melanocytic tumors, including intermediate lesions known as melanocytomas. We examine the genetic and molecular techniques used to study these tumors, look at where they overlap, and discuss their limitations and some of the most difficult-to-interpret results (AU)

Con el desarrollo de la enfermedad molecular, el diagnóstico y la comprensión de los tumores melanocíticos ha experimentado un avance descomunal en los últimos años. Esto ha significado la aparición de conceptos de difícil asimilación en el mundo clínico, el cual no está siempre en contacto directo con las técnicas genéticas de laboratorio. Al mismo tiempo, sin embargo, al clínico se le está exigiendo una terapéutica basada en muchas ocasiones en los hallazgos moleculares más recientes de un tumor melanocítico. El presente artículo explora los conceptos moleculares más recientes de la clasificación en rutas patogénicas de los tumores melanocíticos, incluidas las formas intermedias conocidas como melanocitomas, y repasa las técnicas auxiliares usadas en el estudio de estos tumores, discutiendo los resultados más complejos, sus limitaciones, y sus solapamientos (AU)

Modern Concepts in Melanocytic Tumors. / Conceptos modernos en tumores melanocíticos.

The advent of molecular pathology has fueled unprecedented advances in the diagnosis and understanding of melanocytic tumors. These advances, however, have also generated concepts that may be difficult to grasp for clinical practitioners, who are not always conversant with the array of genetic techniques employed in the laboratory. These same practitioners, however, are being increasingly called on to provide treatments that are often based on the latest molecular findings for melanocytic tumors. We review the most recent concepts in the pathway classification of melanocytic tumors, including intermediate lesions known as melanocytomas. We examine the genetic and molecular techniques used to study these tumors, look at where they overlap, and discuss their limitations and some of the most difficult-to-interpret results.

Nódulo proliferativo en nevus melanocítico congénito gigante / Proliferative nodule in giant congenital melanocytic nevus

El nevus melanocítico gigante es una entidad poco frecuente. En los primeros meses o años de vida, pueden aparecer nódulos dérmicos pequeños o grandes, muy pigmentados, que pueden crecer rápidamente o incluso ulcerarse. Esto obliga a realizar diagnóstico diferencial con el melanoma. Se presenta el caso de una paciente de 3 años de edad, con gran lesión pigmentada en pierna izquierda, con nódulos de rápido crecimiento, compatibles con nódulo proliferativo.

Giant melanocytic nevi are rare. In the fi rst few months or even years of life, they may develop small or large dermic nodules, very pigmented, with rapid growth o even ulcer formation. This forces the diff erential diagnosis with melanoma. We present a case of a 3 year old female patient, with a large pigmented lesion on the left leg, with nodules compatible with proliferative nodules.

Enfermedades poco frecuentes. Halo nevus. Presentación de un caso clínico / Rare diseases. Halo nevus. Presentation of a clinical case

El Halo Nevus consiste en un área hipopigmentada que rodea un nevus melanocítico preexistente y lo hace desaparecer, dejando una cicatriz hipocrómica en el lugar del nevo. Un 20% puede malignizarse. Se presenta un adolescente con lesiones en sus diferentes estados evolutivos, sin sintomatología adicional, ni antecedentes familiares. Es importante el seguimiento clínico y dermatológico para detectar signos tempranos de malignización con el consiguiente tratamiento oportuno

Summary Halo Nevus consists is an hypopigmented area surrounding a pre-existing melanocytic nevus and make it desappared leaving a hypochromic scar in it place, and 20% may become malignant. We present an adolescent with lesions in their different stages of evolution, without additional symptoms or family history. Clinical and dermatological follow-up is important to detect early signs of malignancy with the following timely treatment

Congenital Melanocytic Nevus Syndrome: A Case Series. / Síndrome del nevus melanocítico congénito. Serie de casos.

Congenital melanocytic nevus syndrome (CMNS) is the result of an abnormal proliferation of melanocytes in the skin and central nervous system caused by progenitor-cell mutations during embryonic development. Mutations in the NRAS gene have been detected in many of these cells. We present 5 cases of giant congenital melanocytic nevus, 3 of them associated with CMNS; NRAS gene mutation was studied in these 3 patients. Until a few years ago, surgery was the treatment of choice, but the results have proved unsatisfactory because aggressive interventions do not improve cosmetic appearance and only minimally reduce the risk of malignant change. In 2013, trametinib was approved for use in advanced melanoma associated with NRAS mutations. This drug, which acts on the intracellular RAS/RAF/MEK/pERK/MAPK cascade, could be useful in pediatric patients with CMNS. A better understanding of this disease will facilitate the development of new strategies.

Evaluación de reactividad inmunohistoquímica con método del Complejo Avidina­Biotina (ABC) / Evaluation of immunohistochemical reactivity with Avidin-Biotin Complex (ABC) method

Inmunohistoquímica es toda técnica que permite detectar in situ componentes celulares y extracelulares por medio de anticuerpos específicos, empleando sistemas de detección enzimáticos. Dentro de los métodos inmunohistoquímicos, la técnica del complejo avidina­biotina(ABC) es ampliamente utilizada debido a su alta sensibilidad. El objetivo del presente estudio fueevaluar la reactividad inmunohistoquímica del anticuerpo 4C4.9 para la detección de la proteínaS-100, utilizando el método ABC. Para la evaluación de la reactividad inmunohistoquímica se utilizaron 2 biopsias de piel humana con diagnóstico histopatológico de melanoma maligno nodular ulcerado y nevus melanocítico intradérmico, provenientes del Laboratorio de Investigación en Biotecnología Animal de la Universidad de La Frontera, Temuco, Chile. Se utilizó el Kit VECTASTAIN®como método de detección, la dilución del anticuerpo 4C4.9 fue 1/250 y la temperatura de incubación fue a 4 ºC ó 37 ºC por 18 horas. Para validar la técnica, se realizó un control positivo y otro negativo para 4C4.9. Los resultados de la tinción inmunohistoquímica por el método del complejo ABC mostraron tinción positiva para la proteína S-100, tanto en melanoma maligno nodular ulcerado, como en nevus melanocítico intradérmico, incubados durante 18 horas a 4 ºC ó 37 ºC. Sin embargo, la inmunotinción fue más intensa cuando el anticuerpo primario se incubó a 37 ºC. Para una correcta interpretación de los resultados, es necesario tener en consideración que la reacción antígeno-anticuerpo se ve influenciada por diversos factores, como la concentración del anticuerpo, el tiempo y la temperatura de incubación. En conclusión, nuestros resultados sugieren incubarlas muestras con el primer anticuerpo (4C4.9) en una dilución de 1/250 en agua destilada, incu-bando durante 18 h a 37 ºC. Se recomienda la utilización del anticuerpo 4C4.9 como apoyo al diagnóstico y diagnóstico diferencial.

Immunohistochemistry is anytechnique that can detect cellular and extracellular components in situ by means of specific antibodies,using enzymatic detection systems. Among immunohistochemical methods, the technique ofavidin - biotin complex (ABC) is widely used because of its high sensitivity. The aim of this study was to evaluate the immunohistochemical reactivity of the4C4.9 antibody for detection of S-100 protein using the ABC method. For the evaluation ofimmunohistochemical reactivity 2 biopsies of humanskin were used with histopathological diagnosis ofulcerated malignant melanoma and melanocyticintradermal nevi from the Research Laboratory onAnimal Biotechnology of the Universidad de La Fron-tera, Chile. The Kit VECTASTAIN® was used asdetection method, the dilution the 4C4.9 antibodywas 1/250 and incubation temperature was at 4 °Cor 37 °C for 18 hours. To validate the technique, apositive control and a negative for 4C4.9 was performed. The results of immunohistochemicalstaining by the method of ABC complex showed positive staining for protein S-100 both in ulcerated malignant melanoma and melanocytic intradermalnevi, incubated for 18 hours at 4 °C or 37 °C.However, immunostaining was more intense when the primary antibody was incubated at 37° C. For acorrect interpretation of the results, it is necessary to take into consideration that the antigen-antibody reaction is influenced by various factors such as the concentration of antibody, time and temperature ofincubation. In conclusion, our results suggest incubating the samples with the first antibody (4C4.9)at 1/250 dilution in distilled water, incubating for 18h at 37 ºC. However, immunostaining was moreintense when the primary antibody was incubated at37° C. For a correct interpretation of the results, it isnecessary to take into consideration that antigen-antibody reaction is influenced by various factors suchas the concentration of antibody, time and temperature of incubation. In conclusion, our results suggest incubating the samples with the first antibody(4C4.9) at 1/250 dilution in distilled water, incubating for 18 h at 37 ºC. The use of the antibody 4C4.9 is recommended to support the diagnosis and differential diagnosis.

[Atypical melanocytic nevus of the limbus. A case report]. / Nevus melanocítico atípico limbar. A propósito de un caso.

CASE REPORT: A 78-year-old-woman presented with a corneal non-pigmented vascularised tumour of her left eye, of 2 months onset, but with no previous ocular disorders. Surgical excision was performed, and the histopathological study showed the lesion to be an atypical melanocytic nevus of the limbus. DISCUSSION: Corneal pigmented lesions tend to occur as a result of conjunctival or sclerocorneal limbus lesions spreading or arising de novo from melanocytic cells that have migrated following corneal injury. A biopsy should be carried out to type and distinguish benign lesions (nevus) from pre-malignant or malignant lesions (primary acquired melanosis or conjunctival melanoma).

Nevo melanocítico congénito gigante: presentación de un caso / Giant congenital melanocitic Nevus: case report

Los nevo melanocíticos congénitos gigantes (NMCG) son lesiones dérmicas que llaman la atención a todo Neonatólogo que hace la primera exploración física en el recién nacido, por lo tanto no pasan inadvertidos. Se caracterizan por placas y nódulos hiperpigmentados que miden desde 4.6 cm hasta varios decímetros pudiendo involucrar una extremidad, o varias regiones anatómicas.Se reporta el caso de neonato femenino de 4 días de edad que presenta placa cutánea hiperpigmentada “en prenda de vestir” que ocupa parte del tronco, abdomen, genitales y región proximal de extremidades inferiores. Esta lesión se acompaña de numerosas pápulas satélites distribuidas en el tronco, cabeza y una tumoración en genitales cuyo diagnóstico histopatológico fue de Neurofibroma.

Giant Pigmented Melanocytic Nevus, a lesion presented in the dermis, is a birthmark that can be noted at first sight by all Pediatric physicians who are performing the first time inspection in newborns, therefore they are not hidden lesions. They are described as plaques or hyperpygmented nodes, with a surface from 0,6cm to the entire trunk, expanded to the limbs and other anatomical zones.We report a clinic case of a female newborn, 4 days old, who present a skin lesion described as a hyperpigmented plaque, its distribution looks like a bathing dress “bathing trunk nevi”, localized in multiple zones such as, the trunk, abdomen, genitals areas and the upper part of the inferior extremities. This lesion is surrounded by numerous satellite papules which are spreading in the trunk and head. Besides that, we describe a tumor located in the genital area whose hystopatological report was Neurofibroma.