Department of Pathology and Laboratory Medicine, Nova Scotia Health Authority (Central Zone), Halifax, NS, Canada.
Department of Ophthalmology, Nova Scotia Health Authority (Central Zone), Halifax, NS, Canada.
Am J Dermatopathol. 2022 Jan 1;44(1):e11-e15. doi: 10.1097/DAD.0000000000001986.
Epithelioid fibrous histiocytoma (EFH) is an uncommon benign skin lesion. It is distinct from FH by virtue of its recurrent anaplastic lymphoma kinase (ALK) gene rearrangements and immunohistochemical expression of ALK protein. It often poses a challenge in interpretation. Clinically, it is characterized by a flesh-colored papule/nodule on an extremity of a young to middle-aged individual. Microscopically, it is represented by a circumscribed dermal papule/nodule composed of sheets of plump epithelioid cells, forming whorled aggregates around numerous intralesional vessels. Immunohistochemistry, notably ALK positivity and relevant negative stains, serves to distinguish EFH from its morphological mimics. Rare examples of chondroblastoma-like EFH and EFH with osseous metaplasia are recorded in the literature. Our case is of a 58-year-old man who attended an oculoplastic surgeon because of an exophytic cutaneous nodule on the right upper eyelid. The lesion was excised. Microscopically, it displayed morphological and immunohistochemical features of EFH. Of interest, discrete foci of chondro-osseous change, including chondroblastoma-like pericellular calcification, osteoid formation, and osteoclast-like giant cells, were noted throughout the lesion. A diagnosis of EFH with chondroblastoma-like features was made. Of interest, the changes observed in this EFH serve to link the previously reported examples of pure chondroblastoma-like EFH and EFH with osseous metaplasia. This morphological variant of EFH adds to the existing diagnostic challenge presented by these lesions, particularly in the distinction from other calcifying tumors of the skin.
上皮样纤维组织细胞瘤 (EFH) 是一种不常见的良性皮肤病变。它与 FH 不同，具有复发性间变性淋巴瘤激酶 (ALK) 基因重排和 ALK 蛋白的免疫组织化学表达。它在解释上经常带来挑战。临床上，它表现为中青年患者四肢的肤色丘疹/结节。镜下，它表现为界限清楚的真皮丘疹/结节，由片状肥胖的上皮样细胞组成，围绕许多瘤内血管形成漩涡状聚集。免疫组织化学，特别是 ALK 阳性和相关的阴性染色，有助于将 EFH 与其形态模拟物区分开来。文献中有记录罕见的软骨母细胞瘤样 EFH 和伴有骨化生的 EFH 。我们的病例是一名 58 岁男性，因右上眼睑的外生性皮肤结节就诊于眼整形科。病变被切除。镜下，它显示出 EFH 的形态和免疫组织化学特征。有趣的是，在整个病变中都观察到离散的软骨-骨样变化焦点，包括软骨母细胞瘤样细胞周围钙化、类骨质形成和破骨样巨细胞。诊断为具有软骨母细胞瘤样特征的 EFH。有趣的是，在这种 EFH 中观察到的变化将以前报道的纯软骨母细胞瘤样 EFH 和伴有骨化生的 EFH 联系起来。这种 EFH 的形态变体增加了这些病变所带来的现有诊断挑战，特别是在与其他皮肤钙化肿瘤的鉴别中。
