Immunohistochemical Study on Acral Lentiginous Melanoma

Kim, You Chan; Lee, Min Geol; Cho, Sang Ho; Choe, Sung Whan; Park, Hyang Joon; Cinn, Yong Woo

Abstract

BACKGROUND: Although clinicopathologic characteristics of acral lentiginous melanoma (ALM) is well established, immunohistochemical study on ALM has rarely been reported.
OBJECTIVE
Our purpose is to evaluate the usefulness of several immune markers in the diagnosis of ALM.
METHODS
An immunohistochemical study was performed on paraffin sections of 20 ALMs using S-100 protein, HMB-45, vimentin, epithelial membrane antigen (EMA), and CAM 5.2.
RESULTS
1. Nineteen (95%) and 16 (80%) out of 20 ALM showed reactivity with S-100 protein and HMB-45, respectively. 2. Melanin bleaching was useful for diagnosing heavily pigmented ALM using both S-100 protein and HMB-45. 3. The immunoreactivity of S-100 protein and HMB-45 did not correlate with tumor thickness or level of invasion of ALM. The intensity of HMB-45 correlated well with the melanin content. 4. One and 2 out of 20 cases stained focally with EMA and CAM5.2 respectively, but these cases stained also with HMB-45 and/or S-100 protein.
CONCLUSION
S-100 protein and HMB-45 were relatively sensitive markers for diagnosing ALM. Despite the occasional positivity for the epithelial markers in ALM, all epithelial marker-positive cases stained also with HMB-45 and/or S-100 protein. Therefore, S-100 protein and HMB-45 are very useful markers for diagnosing ALM.