CTNNB1 somatic mutations drive Wnt pathway activation in a case of incidental intranodal palisaded myofibroblastoma / Mutaciones somáticas de CTNNB1 inducen la activación de la vía Wnt en un caso incidental de miofibroblastoma en empalizada de localización intraganglionar

Intranodal palisaded myofibroblastoma (IPM) is a rare stroma-derived spindle-cell neoplasm of the lymph node with myofibroblastic differentiation and CTNNB1 (β-catenin gene) somatic mutations. We present a case of IPM found incidentally in the staging of lung adenocarcinoma. We describe the major histopathological and phenotypic features, including a palisaded bland spindle cell proliferation with myofibroblastic differentiation and Wnt pathway activation by immunohistochemistry, including β-catenin expression. Production of osteoid-like collagen directly from tumor cells was observed. We confirmed p.Gly34Arg CTNNB1 mutation by direct sequencing. We also reviewed the literature for similar cases.(AU)

El miofibroblastoma en empalizada intraganglionar linfático (MEIG) es una neoplasia infrecuente de células fusiformes del estroma del ganglio linfático con diferenciación miofibroblástica y mutaciones en CTNNB1 (gen de la β-catenina). Aquí mostramos el caso de un paciente con MEIG encontrado incidentalmente en la estadificación por un adenocarcinoma de pulmón. Se describen las características histopatológicas principales de la entidad, incluyendo una proliferación de células fusiformes con escasa atipia, empalizadas celulares y diferenciación miofibroblástica con activación de la vía Wnt, incluyendo expresión inmunohistoquímica de β-catenina. Se observó producción de colágeno de tipo osteoide por parte de las células tumorales. Se confirmó la presencia de la mutación p.Gly34Arg de CTNNB1 mediante secuenciación directa. Se recogen adicionalmente publicaciones de casos similares al nuestro.(AU)

Intestinal infantile fibrosarcoma with translocation of NTRK. A case report and review of the literature / Fibrosarcoma intestinal infantil con translocación de NTRK y revisión de casos de la literatura

Introduction: Infantile fibrosarcoma is a rare non-rhabdomyosarcomatous soft tissue tumor (0.0005%) of which only 10% occur in the abdomen where they rarely affect the gastrointestinal tract. The median age at diagnosis is 3 months although 40% of them are present at birth. Material and methods: When infantile fibrosarcoma is diagnosed in our center, a clinical–pathological description is made together with a bibliographic review. Results: We present the case of a 6-day-old girl who presented with irritability and rejection of food. She was diagnosed with acute abdomen due to perforation and underwent surgery where a mass on the ascending colon was removed. Histopathology revealed a proliferation of spindle cells consisting of intertwined fascicles, infiltrating the adjacent tissues. Nuclear pleomorphism, few mitoses, foci of necrosis and hemorrhage are seen. Immunohistochemistry showed positivity for Pan-TRK and the NGS panel (Archer DX) demonstrated the TPR::NTRK1 fusion. No case with these characteristics, location or TPR::NTRK1 fusion were found in the literature. Conclusions: Infantile fibrosarcoma is a very infrequent tumor which is exceptionally rare in the intestine. It is important to look for the characteristic genetic rearrangement of these tumors both to confirm the diagnosis and differentiate them from other pediatric spindle cell tumors and determine the correct targeted treatment. Selective TRK inhibitors have shown a 75% response rate in children and adults with tumors that exhibit TRK fusion. It was possible to find fusions with the Archer DX panel that the Oncomine panel did not detect.(AU)

Introducción: El fibrosarcoma infantil es un tumor infrecuente del tejido blando no rabdomiosarcomatoso (0,0005%). Solo el 10% se produce en el abdomen y pocos de ellos afectan al tracto gastrointestinal. La edad media de su diagnóstico es de 3 meses, presentándose el 40% de ellos al nacer. Material y métodos: Con motivo del diagnóstico de un caso de fibrosarcoma infantil en nuestro centro realizamos una descripción clínico-patológica del mismo, y llevamos a cabo una revisión de la literatura al respecto. Resultados: Presentamos el caso de una niña de 6 días de edad, que inició con irritabilidad y rechazo de alimentos, a quien se diagnosticó abdomen agudo debido a perforación. En la intervención quirúrgica se extirpó una masa dependiente en el colon ascendente. El estudio histológico mostró una proliferación de células fusiformes compuesta de fascículos entrelazados, con infiltración en los tejidos adyacentes. Se identificaron pleomorfismo nuclear, pocas mitosis, focos de necrosis y hemorragia. Se obtuvo positividad inmunohistoquímica para Pan-TRK, demostrando el panel de NGS (Archer DX) la fusión TPR::NTRK1. No encontramos en la literatura ningún caso con estas características, localización intestinal y fusión TPR::NTRK1. Conclusiones: El fibrosarcoma infantil es un tumor muy raro, siendo excepcional la localización intestinal. Es importante la búsqueda de la reorganización genética característica de estos tumores, tanto para esclarecer el diagnóstico como para diferenciarlos de otros tumores de células fusiformes de aparición en niños, así como para aportar un tratamiento focalizado. Los inhibidores selectivos de TRK han reflejado una tasa de respuesta del 75% en niños y adultos con tumores que exhiben fusión de TRK. Fue posible encontrar fusiones utilizando el panel Archer DX, no detectadas por el panel Oncomine.(AU)

Intestinal infantile fibrosarcoma with translocation of NTRK. A case report and review of the literature.

INTRODUCTION: Infantile fibrosarcoma is a rare non-rhabdomyosarcomatous soft tissue tumor (0.0005%) of which only 10% occur in the abdomen where they rarely affect the gastrointestinal tract. The median age at diagnosis is 3 months although 40% of them are present at birth. MATERIAL AND METHODS: When infantile fibrosarcoma is diagnosed in our center, a clinical-pathological description is made together with a bibliographic review. RESULTS: We present the case of a 6-day-old girl who presented with irritability and rejection of food. She was diagnosed with acute abdomen due to perforation and underwent surgery where a mass on the ascending colon was removed. Histopathology revealed a proliferation of spindle cells consisting of intertwined fascicles, infiltrating the adjacent tissues. Nuclear pleomorphism, few mitoses, foci of necrosis and hemorrhage are seen. Immunohistochemistry showed positivity for Pan-TRK and the NGS panel (Archer DX) demonstrated the TPR::NTRK1 fusion. No case with these characteristics, location or TPR::NTRK1 fusion were found in the literature. CONCLUSIONS: Infantile fibrosarcoma is a very infrequent tumor which is exceptionally rare in the intestine. It is important to look for the characteristic genetic rearrangement of these tumors both to confirm the diagnosis and differentiate them from other pediatric spindle cell tumors and determine the correct targeted treatment. Selective TRK inhibitors have shown a 75% response rate in children and adults with tumors that exhibit TRK fusion. It was possible to find fusions with the Archer DX panel that the Oncomine panel did not detect.