[490] Insulin-Like Growth Factor-II Messenger RNA Binding Protein-3 (IMP-3) Expression in Nodal Nevi and Metastatic Melanoma

R Sharma, M Pletneva, PB Illei. Johns Hopkins Medical Institutions, Baltimore, MD

Background: IMP-3 is expressed during embryogenesis and several malignant epithelial tumors. Recently, IMP-3 expression was reported in primary and metastatic melanomas but not in cutaneous nevi including atypical nevi (Mod Pathol, 2008; 21: 431-437) with higher expression levels in metastatic tumors. The presence of nodal nevi primarily in axillary and inguinal lymph nodes can pose a diagnostic difficulty especially in sentinel lymph nodes. In some cases, immunohistochemistry for Melan-A and Hmb-45 cannot distinguish between beni nevi and micrometastic melanoma.
Design: We have performed immunohistochemistry for Melan-A, Hmb45 and IMP-3 (DAKO, Carpintera, CA) in 9 lymph nodes with nodal nevi and 12 lymph nodes involved by metastaic melanoma.
Results: All 9 nevi and all 12 melanomas were Melan-A positive. All 12 melanomas were Hmb45 positive and weak staining was also seen three nodal nevi. IMP-3 postivity was seen in 11 of 12 melanomas and focal weak staining in 1 of 9 nodal nevi.
Conclusions: Based on the limited number of cases in this pilot study immunohistochemistry for IMP-3 could be helpful in differentiating benign nodal cells from micrometastatic melanoma.
Category: Dermatopathology

Tuesday, March 10, 2009 8:30 AM

Platform Session: Section E, Tuesday Morning