[490] D2-40 Expression in Epithelioid Fibrous Histiocytoma.

Jyoti P Kapil, Michael S McLemore, Victor G Prieto. George Washington University Hospital, Washington, DC; UT – MD Anderson Cancer Center, Houston, TX

Background: Epithelioid fibrous histiocytoma (EFH) is a variant of benign fibrous histiocytoma (BFH) that has a distinct histologic appearance but can be easily confused with other neoplasms, including melanocytic lesions. By immunohistochemistry (IHC), EFH is positive for factor XIIIa and CD68. D2-40, a lymphatic endothelial and dendritic cell marker, has been proposed as a very sensitive marker for standard BFH (100% of cases in a single series). However, no study has examined D2-40 expression specifically in EFH.
Design: For the present study, we searched the pathology files of our institution for cases diagnosed as epithelioid fibrous histiocytoma. From 2000-2010, there were nine cases with available slides. We performed IHC for D2-40, Factor XIIIa, CD68, CD163, and S100. Three pathologists reviewed the IHC results and quantified the percentage of epithelioid cells labeled and their intensity on a four-tier scale from 0 (negative) to 3+ (strong).
Results: D2-40 expression was seen in 8/9 cases, and in a majority of cases, greater than 40% of the epithelioid cells showed cytoplasmic and membranous labeling (See Table). Factor XIIIa expression was seen in 7/7 cases, in 5% to 60% of the epithelioid cells. CD68 expression was seen in 8/8 cases, greater than 60% of epithelioid cells in seven cases. CD163 expression was seen in 6/9 with 10% to 80% of epithelioid cells being positive. S100 was not expressed in any case.

DEMOGRAPHIC CHARACTERISTICS AND IMMUNHISTOCHEMISTRY RESULTS FOR OUR CASES OF EPITHELIOID FIBROUS HISTIOCYTOMA

#	Age (years), Sex	Site	D2-40*	FXIIIa*	CD68*	CD163*	S100*
1	68, M	right thigh	40%, 3+	40%, 3+	60%, 2+	-	-
2	40, M	right arm	10%, 1+	NA	NA	10%, 1+	NA
3	46, M	chest	-	20%, 1+	60%, 2+	-	-
4	38, F	external auditory canal	60%, 2+	20%, 1+	90%, 2+	80%, 3+	NA
5	44, M	right shoulder	70%, 2+	60%, 1+	80%, 1+	30%, 3+	NA
6	20, M	arm	90%, 1+	30%, 2+	60%, 2+	30%, 3+	-
7	20, M	nostril	90%, 1+	5%, 1+	10%, 2+	20%, 3+	-
8	24, F	nostril	80%, 2+	10%, 1+	80%, 2+	60%, 3+	-
9	18, F	right shoulder	90%, 3+	NA	100%, 3+	-	-

*% and intensity N/A not available


Conclusions: Our data indicate that EFHs, similar to standard BFHs, also express D2-40, albeit in a lower percentage of cases. Therefore, it seems that if immunohistochemistry is needed in cases difficult to diagnose, a panel of antibodies may be necessary, including D2-40, Factor XIIIa, and CD68.
Category: Dermatopathology

Monday, February 28, 2011 1:30 PM

Platform Session: Section F, Monday Afternoon