Uncommon case of the acral melanoma with chondro-osseous metaplasia

Abstract

Aim. This study aimed to improve the diagnostics of acral melanoma and investigate tumor morphological features of the chondroid and osseous matrix. Materials and methods. The article presents a clinical case of metastatic acral melanoma with chondroid and osseous metaplasia in a 60-year-old patient. Cytological, histologic, immunohistochemical, and molecular genetic studies were performed. Results. A conglomerate of lymph nodes was noted in the inguinal region of the patient. Oxyphilic chondroid masses and tumor cells with morphological features of sarcoma were revealed using thin-needle aspiration biopsy. On physical examination, pink-colored subcutaneous neoplasm was discovered in the skin of the heel. Histological examination of the primary neoplasm and inguinal lymph node was performed. Melanoma with chondro-osseous metaplasia was diagnosed. Immunohistochemical examination of the tumor revealed some pronounced diffuse expressions of S-100 protein, HMB-45, and focal expression of Melan A in tumor cells. The sample was tested to detect BRAF mutation, and no mutations were found. Conclusion. Morphological diagnostics of acral melanoma with chondro-osseous metaplasia is characterized by a high risk of diagnostic error. Therefore, additional immunohistological, molecular, and genetic studies should be used in the diagnostics of acral melanoma with chondro-osseous metaplasia.