Cartilaginous melanoma: case report and review of the literature
A 47-year-old woman presented with a painful subungual lesion on the right big toe which appeared one year before as a hyperkeratotic lesion and treated with oral terbinafine, with no improvement. Twelve years ago she underwent laser therapy for a lesion at the same location. A histopathological examination was not performed.\nPhysical examination revealed a painful subungual nodule on her right big toe. There was no regional lymphadenopathy.\nAn excisional biopsy of the nodule was performed. Histopathological examination showed an ulcerated tumor extending in a diffuse pattern from the epidermis to the inferior limit of the specimen. Rounded cells with vesicular nucleus, scant cytoplasm, numerous mitotic figures, dyskeratotic and apoptotic cells were observed ().\nThe presence of nests of large, bizarre chondrocytes embedded in a chondroid matrix was observed in around one third of the lesion, strongly suggesting positivity for Alcian Blue ().\nOn the periphery of the specimen hyperplasia and acanthosis of epidermis were observed as well as intracytoplasmic melanin pigment in small aggregates (). Nests of atypical melanocytes were observed at the dermoepidermal junction without evidence of pagetoid spread, and isolated atypical melanocytes were present in the upper dermis ().\nImmunohistochemistry showed positivity of the junctional component and of melanocytes in the upper dermis for S-100 protein and positivity of the tumor cells for HMB-45 (, and ). The cartilaginous component showed positivity for S-100 protein and for neuron specific enolase (). We diagnosed melanoma with cartilaginous differentiation. The tumor had a Breslow depth higher than 5 mm (Clark level V).\nThe patient subsequently underwent amputation of the distal phalanx of the big right toe. Histopathological examination of the lesion confirmed the biopsy findings of malignant melanoma with cartilaginous differentiation, with a Breslow thickness of 9,9 mm and a Clark level of V. Sentinel lymph node biopsy was also performed, which proved negative for tumor. According to the TNM staging this malignant melanoma was T4b N0 M0, stage II B.\nTwo years after surgery an ulcerated lesion at the same location appeared. This was excised and proved by histopathological examination to be a local recurrence. The big and second toes were amputated. This subsequent wider excision showed no residual melanoma.\nNeither local recurrence nor metastasis were observed during the following three years of followup.