Plaza Jose Antonio, Wakely Paul E, Suster Saul
Department of Pathology, Division of Anatomic Pathology, Ohio State University, Columbus, USA.
Am J Surg Pathol. 2006 Mar;30(3):337-44. doi: 10.1097/01.pas.0000194297.81721.1c.
Benign nerve sheath tumors of soft tissue can occasionally adopt unusual or unfamiliar morphologic appearances that may introduce difficulties for diagnosis, such as multinucleation, bizarre nuclei, intranuclear vacuoles, and other degenerative changes. Tumor cells adopting a signet-ring or lipoblast-like configuration, however, are mostly associated with epithelial malignancies, liposarcoma and melanoma, and have been only rarely observed in spindle cell tumors of soft tissue. We report 5 cases of benign nerve sheath neoplasms that displayed prominent signet-ring cells with lipoblast-like features. The cases presented as solitary soft tissue masses in the groin, thigh, retroperitoneum, and shoulder in 4 men and 1 woman between the ages of 31 to 57 years. Four tumors predominantly showed features of schwannoma and one of neurofibroma; however, intimately admixed with the spindle cell population, there were also numerous scattered mature adipocytes as well as lipoblast-like cells displaying a signet-ring cell appearance. Immunohistochemical studies showed strong S-100 protein positivity in the spindle cells as well as in the signet-ring lipoblast-like cells and the mature adipocytes. The signet-ring cells were negative for mucin stains, cytokeratin, EMA, CEA, and several other differentiation markers. Ultrastructural examination was performed in 2 cases. The signet-ring cells contained large cytoplasmic lipid droplets that displaced the nuclei to the periphery, consistent with lipoblastic differentiation, whereas complex, interdigitating cytoplasmic processes covered by basal lamina material characteristic of nerve sheath differentiation could be identified in the spindle cells. Four patients for whom follow-up was available were alive and well with no evidence of recurrence over a period of 28 to 116 months (median follow-up, 50 months). The presence of mature fat and signet-ring lipoblast-like cells within a nerve sheath neoplasm is quite rare and may signify a process of aberrant differentiation. Neurogenic tumors should be added in the differential diagnosis of spindle cell tumors capable of displaying prominent signet-ring cell features.
软组织良性神经鞘瘤偶尔会呈现出不寻常或不常见的形态学表现，这可能给诊断带来困难，比如多核现象、怪异核、核内空泡以及其他退行性改变。然而，呈现印戒样或脂肪母细胞样形态的肿瘤细胞大多与上皮恶性肿瘤、脂肪肉瘤和黑色素瘤相关，在软组织梭形细胞瘤中仅罕见观察到。我们报告5例良性神经鞘瘤，其显示出具有脂肪母细胞样特征的显著印戒细胞。这些病例表现为31至57岁的4名男性和1名女性腹股沟、大腿、腹膜后和肩部的孤立性软组织肿块。4个肿瘤主要表现为神经鞘瘤特征，1个表现为神经纤维瘤特征；然而，在梭形细胞群体中紧密混合存在着大量散在的成熟脂肪细胞以及呈现印戒细胞外观的脂肪母细胞样细胞。免疫组化研究显示梭形细胞以及印戒样脂肪母细胞样细胞和成熟脂肪细胞中S-100蛋白呈强阳性。印戒细胞对黏液染色、细胞角蛋白、EMA、CEA和其他几种分化标志物呈阴性。对2例进行了超微结构检查。印戒细胞含有大的细胞质脂滴，使细胞核移位至周边，符合脂肪母细胞分化，而在梭形细胞中可识别出被神经鞘分化特征性的基底膜物质覆盖的复杂、相互交错的细胞质突起。有随访资料的4例患者在28至116个月（中位随访时间，50个月）期间存活且状况良好，无复发迹象。神经鞘瘤内存在成熟脂肪和印戒样脂肪母细胞样细胞相当罕见，可能意味着异常分化过程。在能够显示显著印戒细胞特征的梭形细胞瘤的鉴别诊断中应加入神经源性肿瘤。
