Podoplanin

Podoplanin is a 38 kDa type I membrane mucoprotein with several O-glycosylation sites. Such proteins have been found as receptors for selectins which mediate inflammatory cell adhesion. It was initially identified on the foot processes of glomerular epithelial cells and has been linked to the flattening of foot processes in experimental puromycin-induced nephrosis (hence the name podoplanin, as in pes planus, flat foot)². It is also expressed by lymphatic but not blood vessel endothelium.

Immunohistochemical expression

• Lymphangioma

• Kaposi sarcoma

• some angiosarcomas

Podoplanin and D2-40 show very similar reults¹.

			Podoplanin	D2-40
	Mesothelioma	epithelioid	25/29 (staining was seen in the same 25 cases that showed positivity with D2-40)1, 3/33	25/29 (better differentiated tumours show thick continuous membrane staining. In poorly differentiated tumours, membrane staining is discontinuous or staining is dot-like. Intracytoplasmic globoid staining may occur.)1
		biphasic	4/5 (positivity confined to the epithelioid component)1, 1/13	4/5 (positivity confined to the epithelioid component)1
		sarcomatoid	0/61	0/61
		peritoneal deciduoid	1/13
	Adenocarcinoma	lung	0/241,0/63	0/241
		ovary	0/171	0/171
		endometrium	0/51	0/51
		breast	0/101, 0/50 (40 invasive ductal, 10 invasive lobular)3	0/101
		pancreas	0/51	0/51
		stomach	0/51,0/83	0/51
		colon	0/101	0/101
		biliary tract	0/201
		kidney	0/101	0/101
		prostate	0/51	0/51
		ovary	0/61
		thyroid	0/31	0/31
	Adenomatoid tumour		2/21	2/2 (staining is of the apical cell membrane)1
	Squamous carcinoma	lung	0/101, 0/13	0/101
		maxillary sinus	0/23
		skin	0/13
	Neuroendocrine tumour	carcinoid	0/23
		phaeochromocytoma	0/33
	Angiosarcoma		2/51	2/51
	Synovial sarcoma	biphasic	4/6 (positivity confined to the epithelioid component)1	4/6 (positivity confined to the epithelioid component)1
		monophasic	0/61	0/61

Diagnostic utility

• A potential marker for epithelioid mesotheliomas, useful in the differentiation from adenocarcinoma⁴.

References

¹ Ordonez NG D2-40 and podoplanin are highly specific and sensitive immunohistochemical markers of epithelioid malignant mesothelioma. Hum Pathol 2005; 36:372-80

² Breiteneder-Geleff S, Matsui K, Soleiman A, et al. Podoplanin, novel 43-kd membrane protein of glomerular epithelial cells, is down-regulated in puromycin nephrosis. Am J Pathol 1997; 151:1141-52

³ Kimura N,Kimura I. Podoplanin as a marker for mesothelioma. Pathol Int 2005; 55:83-6

⁴ Ordonez NG. Immunohistochemical diagnosis of epithelioid mesothelioma: an update. Arch Pathol Lab Med 2005; 129:1407-14 FULL TEXT

This page last revised 28.7.2006.

©SMUHT/PW Bishop