Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, 110001, China.
Diagn Pathol. 2012 Nov 13;7:155. doi: 10.1186/1746-1596-7-155.
Pleomorphic lipoma is a relatively uncommon entity, and is considered as a variant of spindle cell lipoma. Histologically, spindle cell lipoma/pleomorphic lipoma consists of varying quantity of mature fat, bland spindle cells and ropey collagen. In addition, pleomorphic lipoma is characterized by multinucleate giant cells, which possess the "floret-like" nuclei and marked pleomorphism. So, in contrast to spindle cell lipoma, pleomorphic lipoma is more easily misdiagnosed as a malignant tumor. Herein, we report a peculiar case of pleomorphic lipoma occurring in axilla with entirely devoid of mature fat in a 71-year-old male. The histopathological findings demonstrated the tumor was made up of bland spindle cells admixed with scattered "floret-like" cells and irregular ropey collagen in an extensive myxoid stroma. Immunostaining showed that the tumor was positive for the Vimentin, Bcl-2 and CD34, and was negative for S-100, desmin, CD68, and α-SMA. Although no fat component was found in the whole section, the tumor was still diagnosed as a pelomprphic lipoma. To our knowledge, this is the third reported case of pelomprphic lipoma which entirely lacked lipomatous component. Because of the existence of atypical multinucleate giant cells and lack of mature fat, this tumor may be easily misdiagnosed nonlipomatous lesions, such as myxoid fibrosarcoma, giant cell fibroblastoma. So, it is necessary to pay careful attention to the histological spectrum of pleomorphic lipoma, including the tumor with devoid of fat, and it should be kept in mind that pelomprphic lipoma still can be diagnosed even if lacking lipomatous component.
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多形性脂肪瘤是一种相对罕见的实体瘤，被认为是梭形细胞脂肪瘤的一种变体。组织学上，梭形细胞脂肪瘤/多形性脂肪瘤由不同数量的成熟脂肪、温和的梭形细胞和绳状胶原组成。此外，多形性脂肪瘤的特征是多核巨细胞，具有“花瓣样”核和明显的多形性。因此，与梭形细胞脂肪瘤相比，多形性脂肪瘤更容易被误诊为恶性肿瘤。在此，我们报告了一例发生在腋窝的多形性脂肪瘤的特殊病例，该病例中 71 岁男性的成熟脂肪完全缺失。组织病理学发现，肿瘤由温和的梭形细胞组成，伴有散在的“花瓣样”细胞和广泛黏液样基质中的不规则绳状胶原。免疫组化染色显示，肿瘤表达波形蛋白、Bcl-2 和 CD34，而不表达 S-100、结蛋白、CD68 和α-SMA。尽管整个切片中未发现脂肪成分，但肿瘤仍被诊断为多形性脂肪瘤。据我们所知，这是第三例完全缺乏脂肪成分的多形性脂肪瘤报道。由于存在非典型多核巨细胞和缺乏成熟脂肪，该肿瘤可能容易误诊为非脂肪性病变，如黏液纤维肉瘤、巨细胞成纤维细胞瘤。因此，有必要仔细注意多形性脂肪瘤的组织学谱，包括缺乏脂肪的肿瘤，并应牢记即使缺乏脂肪成分，仍可诊断为多形性脂肪瘤。
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