Unusual variants of cutaneous melanoma

Great mimicker – a case of occult melanoma displaying ganglioneuroblastic differentiation

“…When considering the differential diagnosis of melanoma with ganglioneuroblastic differentiation, possibilities such as a collision tumour with metastatic ganglioneuroblastoma, ectomesenchymoma, malignant peripheral nerve sheath tumour, malignant rhabdoid tumour, malignant melanotic nerve sheath tumour, and rhabdomyosarcoma/triton tumour must be considered [ 1 ]. The first possibility was excluded based on clinical presentation, while the remaining entities were excluded through immunophenotyping, which revealed retained expression of H3K27me3 and INI1, as well as negative staining for desmin and MyoD1.…”

“…Melanomas are widely recognized for their diverse morphological features, which can resemble various other types of tumours, posing a challenge for surgical pathologists in both primary cutaneous and metastatic sites [ 1 , 2 ]. Uncommon variations of melanoma may exhibit distinct cytological characteristics such as balloon cells, signet-ring cells, rhabdoid cells, clear cells, giant cells, or small round cells.…”

“…Additionally, they may display unique histomorphological traits including myxoid change, osteosarcomatous differentiation, and pseudoglandular or angiomatoid change. The occurrence of ganglioneuroblastic differentiation in melanocytic lesions is exceedingly rare, with only a few documented cases in the literature [ 1 ]. Histologically, this phenomenon is characterized by the presence of ganglion-like cells, exhibiting abundant granular eosinophilic cytoplasm with Nissl substance, well-defined cell boundaries, enlarged and eccentric nuclei, prominent nucleoli, and a neuropil background.…”