Differential expression of melanocytic markers in myoid, lipomatous, and vascular components of renal angiomyolipomas.
BACKGROUND
Renal angiomyolipoma is a tumor composed of varying amounts of fat, smooth muscle, and blood vessels. Characteristically, tumor cells express melanocytic markers such as HMB-45 and Melan-A. Recently, several other markers have been described as having excellent diagnostic sensitivity in cutaneous melanocytic lesions.


OBJECTIVE
To compare the sensitivities of 5 melanocytic markers in renal angiomyolipoma and to study the expression patterns of these markers in the 3 different components of angiomyolipoma.


METHODS
A tissue microarray of 20 renal angiomyolipomas was constructed. For each case, 3 cores containing fat, blood vessels, and smooth muscle were taken. The tissue microarray was then stained for HMB-45, Melan-A, tyrosinase, NK1-C3, and CD117.


RESULTS
HMB-45 was positive in 95%, Melan-A in 85%, NK1-C3 in 70%, tyrosinase in 50%, and CD117 in 40% of the cases. All (20/20) were positive for HMB-45 and Melan-A combined. These 5 markers had different sensitivities in the 3 components. HMB-45 was positive in 90%, 85%, and 80% of fat, smooth muscle, and blood vessel components, respectively; Melan-A in 70%, 60%, and 40%; NK1-C3 in 55%, 55%, and 45%; tyrosinase in 30%, 40%, and 10%; and CD117 in 20%, 40%, and 10%, respectively, of these 3 components.


CONCLUSIONS
HMB-45 and Melan-A combined were positive in 100% of the renal angiomyolipomas. We recommend the use of these 2 markers in the workup of this entity, including those with predominantly 1 component. Other melanocytic markers are of limited use. A tissue block comprising predominantly fat or smooth muscle components should be used when performing melanocytic marker immunostain.
Roma
Andres A
AA
Department of Anatomic Pathology, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195, USA.
Magi-Galluzzi
Cristina
C
Zhou
Ming
M
D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D018207:Angiomyolipoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001808:Blood Vessels / Q000378:metabolism / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D058965:MART-1 Antigen; D008297:Male; D008544:Melanocytes / Q000378:metabolism* / Q000473:pathology; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D014442:Monophenol Monooxygenase; D019009:Proto-Oncogene Proteins c-kit