Metastatic signet-ring cell melanoma in a patient with an unknown primary tumor: Histologic, immunohistochemical, and ultrastructural findings

摘要: Abstract Signet-ring cell melanoma is a rare morphologic variant of malignant melanoma. We describe 27-year-old man with widespread cutaneous and internal metastases an unknown primary tumor. One skin biopsy specimen fine-needle aspirate showed polygonal tumor cells consistent the diagnosis metastatic melanoma, but second revealed neoplastic signet-ring appearance. Both specimens, however, yielded identical immunohistochemical findings. Tumor were positive for vimentin S-100 protein reacted markers HMB-45 NKI-C3. Ultrastructural studies abundant intermediate filaments in cytoplasm celk Based on these findings, was made. In this report we fourth case discuss how may lead to that have divergent appearances same patient.