Melanoma with osteocartilaginous differentiation

Subungual melanoma with cartilaginous differentiation: Molecular insights

“…Notably, the tumor harbored a homozygous deletion of the CDKN2A locus, a well-established oncogenic event in melanoma pathogenesis. 22 Amplification of RICTOR on 5p13.1, also identified in our case, occurs in a subset of melanomas and has been associated with poor prognosis and the development of resistance to certain therapeutic agents. 23,24 Interestingly, the tumor also demonstrated heterozygous loss of the EXT2 locus on chromosome 11p11.2.…”

“…Despite the absence of detectable pathogenic variants, chromosomal microarray analysis revealed a structurally complex genome marked by numerous chromosomal alterations involving several key genes. Notably, the tumor harbored a homozygous deletion of the CDKN2A locus, a well‐established oncogenic event in melanoma pathogenesis 22 . Amplification of RICTOR on 5p13.1, also identified in our case, occurs in a subset of melanomas and has been associated with poor prognosis and the development of resistance to certain therapeutic agents 23,24 …”

“…Cartilaginous differentiation in melanoma, while exceedingly rare, has been reported in both primary and metastatic cases 2–22 . This phenomenon can manifest as purely cartilaginous differentiation, as exemplified by our case, or as a composite of cartilaginous and osteoid elements, known as osteocartilaginous differentiation.…”

“…When present in melanoma, a cartilaginous component generally exhibits increased cellularity, cytological atypia, and/or mitotic activity, supporting transdifferentiation into chondrosarcoma, rather than a metaplastic change to benign cartilage. [4][5][6]8,[10][11][12]15,16,18,[20][21][22] These melanomas typically occur in older patients without a clear sex predilection. They often arise at acral sites, especially subungually, but cases have been documented in diverse anatomic locations, including mucosal sites and skin of chronic and intermittent sun exposure.…”

“…This phenomenon can manifest as purely cartilaginous differentiation, as exemplified by our case, or as a composite of cartilaginous and osteoid elements, known as osteocartilaginous differentiation. When present in melanoma, a cartilaginous component generally exhibits increased cellularity, cytological atypia, and/or mitotic activity, supporting transdifferentiation into chondrosarcoma, rather than a metaplastic change to benign cartilage 4–6,8,10–12,15,16,18,20–22 . These melanomas typically occur in older patients without a clear sex predilection.…”