Alpha-lactalbumin, ALA

Alpha-lactalbumin is a 14 kD glycoprotein that facilitates the use of glucose by lactose synthetase. There is structural homology with human lysozyme, raising the possibility of cross reaction on immunohistochemistry.

Immunohistochemical expression

This protein is synthesized in breast tissue.   It is expressed by normal breast tissue, in fibrocystic disease and in breast tumours.  It is also expressed in hidradenoma papilliferum of the vulva. However, its low sensitivity and its presence in a large range of other tumours negate its diagnostic utility.

 

Breast

 

  

  ductal carcinoma

5/101

  lobular carcinoma

5/101

Vulval Paget's disease

1/21

Skin eccrine carcinoma

6/131

Ovarian carcinoma

7/101

Uterine adenocarcinoma

4/101

Pancreatic carcinoma

5/101

Colonic carcinoma

6/101

Prostatic carcinoma

4/101
   

Diagnostic utility

Although once advocated as a marker for mammary carcinoma, it is greatly inferior to GCDFP-15, ER and PR and no longer has a role.

References

1Wick, M. R., T. J. Lillemoe, et al. (1989). "Gross cystic disease fluid protein-15 as a marker for breast cancer: immunohistochemical analysis of 690 human neoplasms and comparison with alpha-lactalbumin." Hum Pathol 20(3): 281-7.

©SMUHT/PW Bishop