Wednesday, December 28, 2005

Immunohistochemistry Examples of Use

Immunohistochemistry- examples of usage and explanation

  • S-100 stains many things including cells of melanocytic origin and certain types of histiocytes. Example: Suspected choroidal melanoma without pigment. In Rosai-Dorfman disease emperipolesis will be easy to identify.

  • HMB-45 stains melanocytes. Example as above or PAM with atypia to identify transepithelial migration.

  • BCL-1 This is a cyclin D derived protein, one of the regulators of the G1 restriction point, which act in phosphorylation and inactivation of the Rb protein gene. BCL-1 is expressed in proliferating cells. BCL-1 may be over-expressed in mantle zone derived lymphomas but usually not in other low grade lymphomas.

  • BCL-2 This is an anti-apoptotic protein that is integral to cell death pathways. It was first noted to be expressed in lymphomas, but is expressed by many cells.

  • CD-1 stains certain types of histiocytes, activated T cells. Example used in combination with S-100 in Langerhans histiocytosis.

  • CD-1a fairly specific for Langerhans cell histocytosis (LCH), dendritic cells in T cell lymphomas. Useful in Rosai Dorfman disease in which histiocytes are negative. Also negative in Erdheim-Chester Disease (ECD) , and juvenile xanthogranuloma (JXG).

  • CD45 identifies cells hematopoietic origin

  • CD68 identifies cells of histiocytic origin. Reactive in JXG, ECD.

  • CD-5 e.g. B cell associated antigen, negative in MALT tumor cells and follicular lymphomas, positive in B cell CLL, mantle cell lymphoma

  • CD-10 e.g. negative in MALT tumor cells, positive follicular lymphomas and a host of other things.

  • CD-34 e.g. stains strongly the tumor cells of solitary fibrous tumor and in fact is part of the definition of that tumor.

  • CD-43 e.g. Sialophorin is the antigen. B-cell antigens in chronic lymphocytic leukemia, stains normal T cells and activated B cells, granulocytes, monocytes. Co-expressed with CD 20 in SLL.

  • CD-3 e.g. T cell marker, useful in most lymphoma evaluations

  • CD-20 e.g. B cell marker useful in most lymphoma evaluations

  • Kappa e.g. light chain restriction in B cell lymphoma evaluations

  • Lamda e.g. light chain restriction in B cell lymphoma evaluations

  • SMA (smooth muscle antigen) e.g. smooth muscle in leiomyomas of the ciliary body

  • EMA (epithelial membrane antigen) e.g. stains sebaceous carcinoma but less often in basal cell carcinoma*; stains adenoid cystic carcinoma

  • CKit (CD117) reacts with adenoid cystic carcinoma more strongly than basal cell carcinoma (but both express it) (see link).

  • CAM 5.2- e.g. special keratin that is positive in sebaceous carcinoma (see link) but less often in squamous carcinoma*

Often panels of immunohistochemistry are most useful. For example:

JXG- positive for CD68, Fascin, XIIIa, alpha-1-antitrypsin but negative for CD1a.
ECD- positive for CD68, XIIIa, but negative for S100 and CD1a.
LCH- negative forCD68, positive for fascin, S100 and CD1a

Lymphangioma versus Hemangioma- podoplanin from lymphangioma. CD 31 stains both.

Conjunctival Nevus versus Melanoma- Ki-67 (proliferation marker), HMB-45 (perhaps more strongly positive in melanoma), MART-1 (defines all melanocytic cells), CD45- ( to distinguish Ki-67 positive inflammatory cells), pankeratin (to distinguish Ki-67 positive epithelial cells) . If possible do these on immediately adjacent sections. Fluorescence in situ hybridization (FISH) may be ordered for confirmation of certain tumors. For conjunctival melanoma, the cytogenetics lab offers 6p23(MYB), 11q13 (CCND1) and centromere 6 probes (CEP6) .

Conjunctiva and Orbital Lymphoma- CD3,CD5,CD10,CD20,CD43,kappa, lambda, BCl2, BCL6, BCl1

Squamous Carcinoma- positive for Ck5-6, P63, pancytokeratin; negative for BerEp4, EMA

*Sebaceous carcinoma is best documented by the presence of abundant lipid in tumor cells. However, the immunohistochemistry is helpful in cases that were not suspected and there is no wet tissue left of the specimen (all in the paraffin block). For the immunohistochemistry see: Sinard JH 1999 Archives of Ophthalmology


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