Cappellesso Rocco, d'Amore Emanuele S G, Dall'Igna Patrizia, Guzzardo Vincenza, Vassarotto Elisa, Rugge Massimo, Alaggio Rita
Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121.
Department of Pathology, San Bortolo Hospital, Vicenza (VI), Italy, 36100.
Hum Pathol. 2016 Jan;47(1):64-9. doi: 10.1016/j.humpath.2015.08.019. Epub 2015 Sep 21.
Lipoblastoma (LB) is a rare benign adipocytic tumor of childhood occasionally showing histological similarities to myxoid liposarcoma (ML) or well-differentiated liposarcoma (WDL). p16 immunohistochemistry has proved to be useful in distinguishing various types of liposarcomas, in particular WDL from lipoma, with higher sensitivity and specificity than MDM2 and CDK4 immunohistochemistry. In this study, we reported the histologic features of a series of 30 LB with emphasis on the potential diagnostic pitfalls and investigated the immunohistochemical expression of p16. Moreover, p16 immunostaining was performed in 16 liposarcomas (11 WDL and 5 ML), 16 lipomas, and 16 cases of liponecrosis in order to evaluate its usefulness in the differential diagnosis of challenging lesions occurring in older children. Overall, p16 immunostaining was positive in 3 LBs and in 12 out of 16 liposarcomas (10 WDL and 2 ML), with a sensitivity of 75%, a specificity of 90%, a positive predictive value of 80%, and a negative predictive value of 87%. All lipomas were p16 negative, whereas 5 liponecroses were positive. Accounting altogether the benign lesions versus liposarcomas, p16 showed a sensitivity of 75%, a specificity of 87%, a positive predictive value of 60%, and a negative predictive value of 93%. Our data suggest that a negative p16 immunostaining may be helpful in excluding a liposarcoma when occurring in unusual clinical contexts, such as in adolescence or late recurrence. However, such finding should be interpreted with caution since also some liposarcomas lack p16 and occasional LBs are positive.
脂肪母细胞瘤（LB）是一种罕见的儿童期良性脂肪细胞肿瘤，偶尔在组织学上与黏液样脂肪肉瘤（ML）或高分化脂肪肉瘤（WDL）相似。p16免疫组化已被证明有助于区分各种类型的脂肪肉瘤，特别是将WDL与脂肪瘤区分开来，其敏感性和特异性高于MDM2和CDK4免疫组化。在本研究中，我们报告了30例LB的组织学特征，重点关注潜在的诊断陷阱，并研究了p16的免疫组化表达。此外，对16例脂肪肉瘤（11例WDL和5例ML）、16例脂肪瘤和16例脂肪坏死病例进行了p16免疫染色，以评估其在鉴别大龄儿童中具有挑战性病变的诊断价值。总体而言，3例LB和16例脂肪肉瘤中的12例（10例WDL和2例ML）p16免疫染色呈阳性，敏感性为75%，特异性为90%，阳性预测值为80%，阴性预测值为87%。所有脂肪瘤p16均为阴性，而5例脂肪坏死呈阳性。综合良性病变与脂肪肉瘤来看，p16的敏感性为75%，特异性为87%，阳性预测值为60%，阴性预测值为93%。我们的数据表明，在不寻常的临床情况下，如青春期或晚期复发时，p16免疫染色阴性可能有助于排除脂肪肉瘤。然而，这一发现应谨慎解读，因为也有一些脂肪肉瘤缺乏p16，偶尔有LB呈阳性。
