Doyle Leona A, Fletcher Christopher D M
Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
J Cutan Pathol. 2011 Sep;38(9):697-703. doi: 10.1111/j.1600-0560.2011.01747.x. Epub 2011 Jul 14.
Epithelioid fibrous histiocytoma (EFH) represents a morphologic variant of cutaneous fibrous histiocytoma (FH) but can lack many characteristic features. The presence of epithelioid cytomorphology may mimic other dermal neoplasms. Our anecdotal experience of epithelial membrane antigen (EMA) expression in some examples of EFH has caused diagnostic difficulty. Our aim was to examine the immunohistochemical profile and incidence of EMA expression in EFH.
Forty-four cases of EFH were retrieved from consultation files. Clinicopathologic and immunohistochemical features were evaluated.
Membranous EMA positivity was found in tumor cells in 27/42 cases (64%). Focal positivity for factor XIIIa was found in 10/14 (71%) and D2-40 in 14/27 (52%). Scattered smooth muscle actin (SMA)-positive tumor cells were seen in 11/43 (25%). Focal positivity for claudin-1 was found in 3/42 (7%). CD163 staining highlighted stromal macrophages; however, in five cases it was difficult to exclude focal staining of tumor cells. Tumor cells were consistently negative for pan-keratin, AE1/AE3, S100, CD31, CD34, CD68, desmin, p63, GFAP and CD45/LCA.
Frequent EMA expression in EFH represents an unexpected finding and constitutes a potential diagnostic pitfall. Although of uncertain significance, this finding, when combined with established morphologic differences, raises the possibility that EFH is unrelated to classic FH.
上皮样纤维组织细胞瘤（EFH）是皮肤纤维组织细胞瘤（FH）的一种形态学变异型，但可能缺乏许多特征性表现。上皮样细胞形态的存在可能会与其他皮肤肿瘤相混淆。我们在一些EFH病例中发现上皮膜抗原（EMA）表达的经验导致了诊断困难。我们的目的是研究EFH中EMA表达的免疫组化特征及发生率。
从会诊档案中检索出44例EFH病例。对其临床病理和免疫组化特征进行评估。
42例中的27例（64%）肿瘤细胞中发现EMA呈膜阳性。14例中的10例（71%）发现因子ⅩⅢa呈局灶阳性，27例中的14例（52%）发现D2-40呈局灶阳性。43例中的11例（25%）可见散在的平滑肌肌动蛋白（SMA）阳性肿瘤细胞。42例中的3例（7%）发现claudin-1呈局灶阳性。CD163染色突出显示间质巨噬细胞；然而，在5例中难以排除肿瘤细胞的局灶性染色。肿瘤细胞对泛角蛋白、AE1/AE3、S100、CD31、CD34、CD68、结蛋白、p63、胶质纤维酸性蛋白（GFAP）和CD45/白细胞共同抗原（LCA）始终呈阴性。
EFH中频繁的EMA表达是一个意外发现，构成潜在的诊断陷阱。尽管其意义尚不确定，但这一发现与已确定的形态学差异相结合，增加了EFH与经典FH无关的可能性。
