IMP-3 expression in melanocytic lesions.
BACKGROUND
Insulin-like growth factor-II mRNA-binding protein 3 (IMP-3 ), a member of the insulin-like growth factor mRNA-binding protein family, is expressed in several human malignancies, including melanomas. However, the expression of IMP-3 has not been explored in melanoma in situ, various histologic subtypes of invasive melanomas and atypical Spitz tumors.


METHODS
IMP-3 immunostain was performed in 157 melanocytic lesions.


RESULTS
Nearly all benign (8/8), dysplastic (8/8) and Spitz nevi (8/9) were negative for IMP-3. Focal IMP-3 positivity was observed in 5/12 melanoma in situ and 4/15 superficial melanomas (Breslow depth <or=1 mm). Half (10/20) of deep melanomas (Breslow depth >1 mm) and 25/52 metastatic melanomas demonstrated strong IMP-3 staining. IMP-3 expression differs significantly between non-desmoplastic melanomas (superficial and deep) and benign or dysplastic or Spitz nevi (p = 0.0427, respectively). Four of 23 desmoplastic melanomas expressed IMP-3 , which was significantly different from deep melanomas (p = 0.0109). IMP-3 stained 7 of 10 atypical Spitz tumors. The difference between atypical Spitz tumors and Spitz nevi was statistically significant (p = 0.0256).


CONCLUSIONS
A malignant circumstance, such as non-desmoplastic melanoma or atypical Spitz tumor, can be inferred when IMP-3 is expressed, suggesting potential diagnostic value of IMP-3 in melanocytic lesions.
Department of Pathology, Dermatopathology Division, University of Michigan, M3260, Medical Sciences 1, 1301 Catherine Street, Ann Arbor, MI 48109-0602, USA.
Limin
L
Yu
Haodong
H
Xu
Matthew J
MJ
Wasco
Patricia A
PA
Bourne
Linglei
L
Ma
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D009506:Nevus / Q000378:metabolism / Q000473:pathology; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
C498780:IGF2BP3 protein, human; D016601:RNA-Binding Proteins