Loss of calponin h1 in renal angiomyolipoma correlates with aggressive clinical behavior.
OBJECTIVE
To investigate whether any immunohistochemical differences exist between two types of renal angiomyolipomas (AMLs). Renal AMLs are generally considered to be benign in nature. However, a few of these tumors have been reported to involve other organs.


METHODS
Tissue specimens from 3 cases of clinically aggressive and 9 cases of clinically indolent renal AMLs were examined histologically and immunohistochemically using antibodies against calponin h1 and alpha-smooth muscle actin. Immunostaining was evaluated semiqualitatively as no staining to strong staining.


RESULTS
The tumor cells in the myomatous component of the aggressive type did not show any reaction to the antibody to calponin h1 protein, but they showed strong immunoreactions with the antibody to the alpha-smooth muscle actin antigen. All cases of the nonaggressive AMLs demonstrated strong immunoreactions with both antibodies used.


CONCLUSIONS
Our initial results in a small series of cases suggest a potential molecular difference between the aggressive and nonaggressive type of AMLs. Loss of calponin h1 from the tumor cells of the aggressive type might be related to their pathologically invasive features, and this aggressive type might be categorized into an intermediate type between the benign and malignant types.
Islam
A H M Manjurul
AH
Department of Urology, Shinshu University School of Medicine, Matsumoto, Japan.
Ehara
Takashi
T
Kato
Haruaki
H
Hayama
Masayoshi
M
Nishizawa
Osamu
O
D000199:Actins / Q000032:analysis; D000328:Adult; D000368:Aged; D018207:Angiomyolipoma / Q000737:chemistry* / Q000145:classification / Q000473:pathology / Q000601:surgery; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000172:deficiency*; D002277:Carcinoma; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007680:Kidney Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D008297:Male; D008840:Microfilament Proteins; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000032:analysis*; D009378:Neoplasms, Multiple Primary; D009392:Nephrectomy; D013274:Stomach Neoplasms; D000096985:Calponins
D000199:Actins; D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D000096985:Calponins