Cartilaginous melanoma: case report and review of the literature

Abstract

Malignant melanoma can present a variety of histopathological patterns. Cartilaginous change in the absence of osteogenic differentiation is extremely rare in malignant melanoma, being among the least frequent of the wide range of melanoma histologic patterns. We report a case of a 47-year-old woman with a subungual nodule on her right great toe for many years. Histopathological examination of the lesion led to a diagnosis of malignant melanoma with cartilaginous differentiation devoid of concomitant osseous areas. It would appear that this unusual form of melanoma has a predilection for acral location, particularly the subungual region. Malignant melanoma with chondroid stroma should therefore be considered in the differential diagnosis of cartilaginous lesions of the toes and fingers. Careful examination of the overlying epidermis and identification of an in situ component of melanoma may be necessary in order to establish the correct diagnosis.

Primary chondro‐osseous melanoma (chondrosarcomatous and osteosarcomatous melanoma)

“…Melanomas with chondro‐osteosarcomatous differentiation have been reported in different locations, including subungual areas of fingers and toes, mucosal in the nose, mouth and vagina, and in other parts of the body such as the face, back, shoulder and ankle . However, there seems to be a predilection of this pattern of melanoma to occur in acral locations, especially the subungual areas of toes and feet .…”

“…Many prior case reports identified such differentiation in either recurrent melanoma or metastatic melanoma, with some exceptions . Hoorweg and colleagues reported 1 case of primary nasal mucosa melanoma with osseous differentiation in a 75 year‐old male .…”

Subungual melanoma with cartilaginous differentiation: Molecular insights

“…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.…”

BRAF‐mutated malignant melanoma with chondrosarcomatous differentiation in inguinal nodal metastasis

“…In fact, most of the reported cases of cartilaginous differentiation seem to have, as common feature, a previous traumatic event, which could drive fibroblasts to cartilaginous differentiation. The overexpression of MIA (melanoma‐inhibiting activity) factor, a soluble autocrine growth factor expressed in most metastatic melanomas, has been suggested to have a relevant role 13‐15 …”