Cohen Philip R, Lee Robert A
Division of Dermatology, University of California San Diego, San Diego, California.
Dermatol Online J. 2014 Mar 17;20(3):doj_21725.
Reticulohistiocytomas are benign dermal tumors that usually present as either solitary or multiple, cutaneous nodules. Reticulohistiocytosis can present as solitary or generalized skin tumors or cutaneous lesions with systemic involvement and are potentially associated with internal malignancy. A woman with a solitary red nodule on her knee is described in whom the clinical differential diagnosis included dermatofibroma and amelanotic malignant melanoma. Hematoxylin and eosin staining and immunoperoxidase studies of the biopsy specimen established the diagnosis of adult-onset reticulohistiocytoma (solitary epithelioid histiocytoma). Reticulohistiocytoma is characterized by mononuclear, and occasionally multinuclear, histiocytes with eosinophilic "glassy" cytoplasm. The immunohistochemical profile of a reticulohistiocytoma demonstrates consistent positive expression for CD68 (a marker that is expressed by histiocytes but can also show positive staining in melanomas and carcinomas), CD163 (a very specific marker for histiocytes), and vimentin. Reticulohistiocytomas show variable positive expression for MITF (microphthalmia transcription factor) and S100 protein, both of which are more commonly used as markers for melanocytes. Recurrence of a reticulohistiocytoma is rare, even for patients with an incompletely removed lesion. However, our patient elected to have her residual tumor completely excised.
网状组织细胞瘤是一种良性皮肤肿瘤，通常表现为单个或多个皮肤结节。网状组织细胞增生症可表现为单个或全身性皮肤肿瘤或伴有全身受累的皮肤病变，并可能与内部恶性肿瘤相关。本文描述了一名膝部有单个红色结节的女性，其临床鉴别诊断包括皮肤纤维瘤和无色素性恶性黑色素瘤。活检标本的苏木精和伊红染色以及免疫过氧化物酶研究确诊为成人型网状组织细胞瘤（孤立性上皮样组织细胞瘤）。网状组织细胞瘤的特征是单核，偶尔为多核的组织细胞，其细胞质呈嗜酸性“玻璃样”。网状组织细胞瘤的免疫组化特征显示CD68（一种由组织细胞表达但在黑色素瘤和癌中也可呈阳性染色的标志物）、CD163（一种非常特异性的组织细胞标志物）和波形蛋白持续阳性表达。网状组织细胞瘤对小眼畸形转录因子（MITF）和S100蛋白呈可变阳性表达，这两种蛋白更常用于黑色素细胞的标志物。网状组织细胞瘤复发罕见，即使对于病变切除不完全的患者也是如此。然而，我们的患者选择将残留肿瘤完全切除。
