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Malignant melanoma with areas of rhabdomyosarcomatous differentiation arising in a giant congenital nevus with RAF1 gene fusion |
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| Authors: | Aline Baltres Aicha Salhi Aurelie Houlier Daniel Pissaloux Franck Tirode Vronique Haddad Marie Karanian Salim Ysmail‐Dahlouk Fatma Boukendakdji Djazia Dahlouk Fateh Allaoua Marzak Metref Assya Djeridane Sylvie Fraitag Arnaud de la Fouchardire |
| Institution: | Aline Baltres,Aicha Salhi,Aurelie Houlier,Daniel Pissaloux,Franck Tirode,Véronique Haddad,Marie Karanian,Salim Ysmail‐Dahlouk,Fatma Boukendakdji,Djazia Dahlouk,Fateh Allaoua,Marzak Metref,Assya Djeridane,Sylvie Fraitag,Arnaud de la Fouchardière |
| Abstract: | A girl, born with a posterior lumbosacral giant congenital nevus, developed a central nodule that expanded over a period of 14 months into a 10‐cm pedunculated mass. Histological analysis of the mass revealed melanoma of myxoid, small round‐cell type with areas of rhabdomyosarcomatous transformation confirmed by immunohistochemistry. RNA sequencing identified an in‐frame SASS6(e14)‐RAF1(e8) fusion in both components and the nevus. A RAF1 FISH break‐apart test found a balanced rearrangement pattern in the nevus and an unbalanced pattern in the malignant areas. Wild‐type status of NRAS and BRAF was confirmed by NGS techniques. The array‐CGH profile displayed copy number alterations commonly found in rhabdomyosarcomas. Despite intensive treatment, widespread metastatic evolution of the melanomatous component was observed. |
| Keywords: | congenital melanoma giant congenital nevus RAF1 fusion rhabdomyosarcomatous differentiation small‐cell melanoma |