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Mucins
Mucins are high molecular weight glycoproteins expressed by epithelial cells. Several mucin genes have ben identified or cloned (MUC1 - MUC12) and monoclonal antibodies raised against their glycoprotein products. Sequence homologies distinguish two main families. The MUC genes at 11p15 encode secreted gel-forming mucins (MUC2, MUC5AC, MUC5B, MUC6). The MUC genes at loci 7q22, 3q and 1q21 encode mainly membrane-bound mucins5.
Like cytokeratins, they show relative specificity for tissue types. MUC1 is identical to EMA.
MUC2 is expressed by mucinous adenocarcinomas of the colon, breast, pancreas and ovary4. CDX-2 may interact with the MUC2 promoter, activating MUC2 expression4.
Immunohistochemical expression
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MUC1 (EMA)
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MUC2
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MUC5AC
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breast
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normal mammary gland
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10/101
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0/101
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0/101
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ductal carcinoma
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13/131
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0/131
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0/131
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GI tract
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stomach
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positive1
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pancreas
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positive1
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intestinal goblet cell
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positive1
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rectal mucosa
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0/101
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10/101
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3/101
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anal glands
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0/61
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0/61
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6/61
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renal cell carcinoma
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26/601
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vulva
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eccrine glands
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12/121
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0/121
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0/121
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apocrine glands
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8/81
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0/81
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0/81
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mammary-like glands
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6/61
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0/61
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0/61
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Bartholin's glands
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7/71
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0/71
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7/71
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cervix
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endocervical glands
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positive1
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Columnar-lined oesophagus commonly expresses MUC5AC and MUC6. MUC2 is only expressed in the presence of intestinal metaplasia3.
MUC4 expression is acquired in dysplastic ectocervical squamous epithelium2:
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normal endocervical glandular epithelium
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11/11, in 50% to 100% of cells
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normal ectocervical squamous epithelium
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4/18, focally in parabasal cells
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squamous metaplasia
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7/9, in 10% to 50% of parabasal cells
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CIN I
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17/19, in all layers of the epithelium
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CIN II
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7/7, in all layers of the epithelium
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CIN III
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9/9, in all layers of the epithelium
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MUC4 is also expressed by intermediate trophoblast:
Diagnostic utility
References
1Kuan, S. F., Montag, A. G., Hart, J., Krausz, T., Recant, W. Differential expression of mucin genes in mammary and extramammary Paget's disease. Am J Surg Pathol 2001;25:1469-1477.
2 Lopez-Ferrer, A., Alameda, F., Barranco, C., Garrido, M., de Bolos, C. MUC4 expression is increased in dysplastic cervical disorders. Human Pathology 2001;32;1197-1202.
3Warson, C., J. H. Van De Bovenkamp, et al. (2002). "Barrett's esophagus is characterized by expression of gastric-type mucins (MUC5AC, MUC6) and TFF peptides (TFF1 and TFF2), but the risk of carcinoma development may be indicated by the intestinal-type mucin, MUC2." Hum Pathol 33(6): 660-8.
4Cathro, H. P. and S. E. Mills (2004). "Immunophenotypic differences between intestinal-type and low-grade papillary sinonasal adenocarcinomas: an immunohistochemical study of 22 cases utilizing CDX2 and MUC2." Am J Surg Pathol 28(8): 1026-32.
5 Handra-Luca A, Lamas G, Bertrand JC, et al. MUC1, MUC2, MUC4, and MUC5AC expression in salivary gland mucoepidermoid carcinoma: diagnostic and prognostic implications. Am J Surg Pathol 2005; 29:881-9
6 Mao TL, Kurman RJ, Huang CC, et al. Immunohistochemistry of choriocarcinoma: an aid in differential diagnosis and in elucidating pathogenesis. Am J Surg Pathol 2007; 31:1726-32
This page last revised 3.1.2008.
©SMUHT/PW Bishop