CD103

Summary

The principle use of CD103 is to identify hairy cell leukaemia (HCL) and distinguish it from related diorders. CD103 also has a wider range of applications in the histopathological identification of a range of myeloid and T-cell disorders.

Normal expression and function

CD103 belongs to the integrin family of adhesion proteins, and directs the adhesion of a subset of T cells within intestinal endothelium and other mucosal sites (binding to E-cadherin). In normal tissues CD103 is found mainly on normal intraepithelial T cells (both alpha-beta or gamma-delta type) and is also expressed by some peripheral regulatory T cells (TRegs) as well as specialised dendritic cells in the gut mucosa and mesenteric lymph nodes.

Diagnostic role

• CD103 is consistently expressed on hairy cell leukemia (HCL) with relatively high (although not complete) specificity.
• CD103 is not generally found on other B-cell lymphomas

Other useful information

In histopathology CD103 is used to identify enteropathy-associated T cell lymphoma, and in lung CD103 has been used in bronchoalveolar lavage to diagnose pulmonary sarcoidosis.

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SUMMARY TABLES

Note The colour and % refer to the proportion of cases expressing the marker. Additional comments on strength, or site of expression (if relevant) are given below the table. For full details of key click here. For further information about a particular disease state click <I> adjacent to the condition name

Expression in primitive cell types
AML	CMML	B ALL	BL	T ALL	ETP ALL	MPAL	Hgn
<5%	<5%	<5%	<5%	<5%	<5%	<5%	<5%

Notes: **While a good marker of B lineage it may not be expressed in more primitive phenotype ALL, there is also a recognised abberrant expression in AML (particularly cases with t)8;21)

Expression in mature B cell neoplasms
CLL	MCL	FL	MZL	HCL	DLBCL	LPL	PCL
<5%	<5%	<5%	<5%	80-100%**	<5%	<5%	<5%

Notes: *typically expressed in HCL where it will be detected in most cases; generally absent in other LPD although rarely expression is detected so the overall pattern is important

Expression in mature T cell neoplasms*
ATLL	CTCL/Sezary	T-PLL	T-LGL	NK-LGL
40-80%	<5%	<5%	<5%	<5%

Notes: Sporadic expression is recognised in many T-cell disorders at around 5% of cases, expression is more frequent in ATLL where just over 40% of cases may express CD103

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