Objective To investigate the clinical pathological characteristics,immunohistochemistry,diagnosis and differential diagnosis,treatment and prognosis of malignant melanoma.Methods The data of 5 cases were reviewed.Results Out of 5 patients,1 patient was female and 4 were males,aged 48 from 92 years (mean age of 67.2 years).Tumors originated from different sites,such as nose,skin and esophagus.Microscopically,the tumor cells were various in morphology from spindle,epithelioid,nevus alike cells to foam alike cells,arranged in nests,stripes or loose nets.Immunohistochemical stain showed positive expressions in S-100,HMB45 in some extent,Melan-A or Vimentin,individually expression CD56 and CgA.However,the levels of CK,EMA,CEA,Desmin,NSE,LCA,CD3,CD20,SMA,MyoD 1,Myogenin and Syn were negatively expressed.Braf and C-kit gene tests were applied in all cases,however,only one case was detected with Braf gene V600E mutation.No case was found with C-kit gene mutations.Conclusion Malignant melanoma is a kind of highly invasive tumor,which is characterized by highly changed morphology and easily misdiagnosis or missed diagnosis.Immunohistochemistry and genetic testing are of great significance in diagnosis and targeted therapy.

Objective To investigate the clinical pathological characteristics,immunohistochemistry,diagnosis and differential diagnosis,treatment and prognosis of malignant melanoma.Methods The data of 5 cases were reviewed.Results Out of 5 patients,1 patient was female and 4 were males,aged 48 from 92 years (mean age of 67.2 years).Tumors originated from different sites,such as nose,skin and esophagus.Microscopically,the tumor cells were various in morphology from spindle,epithelioid,nevus alike cells to foam alike cells,arranged in nests,stripes or loose nets.Immunohistochemical stain showed positive expressions in S-100,HMB45 in some extent,Melan-A or Vimentin,individually expression CD56 and CgA.However,the levels of CK,EMA,CEA,Desmin,NSE,LCA,CD3,CD20,SMA,MyoD 1,Myogenin and Syn were negatively expressed.Braf and C-kit gene tests were applied in all cases,however,only one case was detected with Braf gene V600E mutation.No case was found with C-kit gene mutations.Conclusion Malignant melanoma is a kind of highly invasive tumor,which is characterized by highly changed morphology and easily misdiagnosis or missed diagnosis.Immunohistochemistry and genetic testing are of great significance in diagnosis and targeted therapy.