富于细胞性血管脂肪瘤的临床病理学观察

目的 探讨富于细胞性血管脂肪瘤的临床病理学特点、免疫学表型和鉴别诊断.方法 回顾性复习2例富于细胞性血管脂肪瘤的临床资料和组织学形态,行网状纤维染色,并采用CD31、CD34、FⅧRAg、UEA-1、α-SMA和vimentin等抗体进行免疫组化标记(EnVision法).结果 患者均为男性,年龄分别为38岁和33岁.临床上分别表现为左上臂皮下(例1)、躯干和四肢皮下(例2)多发性小结节,部分结节有疼痛感和触痛感.大体上,结节均有包膜,直径为1～1.5 cm.镜下,例1中的1枚结节呈经典的血管脂肪瘤形态,另2枚结节主要由大量的血管组成,而脂肪组织较少(<5%).网状纤维染色清晰显示丰富的血管结构.部分小血管内可见纤维素性血栓.例2中的2枚结节主要由大量的血管和丰富的梭形间质细胞组成,脂肪组织仅占5%和10%.免疫组化标记显示,富于小血管的区域弥漫强阳性表达CD31、CD34、FⅧRAg、UEA-1和α-SMA,血管之间的梭形间质细胞主要表达vimentin.结论 富于细胞血管脂肪瘤是血管脂肪瘤的一种极为罕见的亚型,可被误诊为梭形细胞脂肪瘤、梭形细胞血管瘤、富于细胞性血管瘤和Kaposi肉瘤等肿瘤.     

去分化脂肪肉瘤28例临床病理分析

目的 探讨去分化脂肪肉瘤(dedifferentiated liposarcoma,DL)中去分化成分的形态学特征.方法 用常规HE染色和免疫组织化学方法,对28例DL进行观察分析.结果 在28例DL中,25例由非典型脂肪瘤样肿瘤/高分化脂肪肉瘤和非脂肪性梭形细胞肉瘤组成;1例为黏液样脂肪肉瘤和非脂肪性梭形细胞肉瘤组成;2例复发性病例未见到高分化脂肪肉瘤成分,均为非脂肪性梭形细胞肉瘤成分.免疫组化:28例中有14例行免疫组化染色,脂肪肉瘤区域脂母细胞S-100蛋白(+),部分脂肪肉瘤中的梭形细胞CD34(+).14例DL中去分化成分3例SMA和HHF35(+),1例desmin和HHF35(+),CD34、CD117、S-100、CD99、AACT、HMB-45、CK、CR均(-),CD68部分病例散在(+).通过对DL的形态学观察发现,去分化区域可以单独或混合呈现以下形态结构:(1)多形性恶性纤维组织细胞瘤样,(2)纤维肉瘤样,(3)低度恶性黏液纤维肉瘤样,(4)纤维瘤病样,(5)平滑肌肉瘤样,(6)脑膜瘤样漩涡结构,(7)横纹肌肉瘤分化,(8)骨/软骨分化,(9)炎性肌纤维母细胞瘤样,(10)血管外皮瘤样等.其中炎性肌纤维母细胞瘤样和血管外皮瘤样结构文献中尚未见报道.结论 DL中去分化成分最常见的结构是高级别肉瘤形态,但也可以是低度恶性黏液纤维肉瘤样、纤维瘤病样、炎性肌纤维母细胞瘤样、血管外皮瘤样等低级别肉瘤形态.可以是单一分化,也可以向平滑肌、横纹肌、骨/软骨等异源性分化.     

树突状纤维黏液脂肪瘤的临床病理学研究

目的探讨树突状纤维黏液脂肪瘤的临床病理特征,并讨论与其他易于混淆的软组织肿瘤的鉴别诊断。方法收集8例树突状纤维黏液脂肪瘤,观察和分析其临床和病理组织学特征,并通过免疫组织化学标记链霉素卵白素生物素(LSAB)法,分析其CD34、bcl-2、波形蛋白、细胞角蛋白(CK)、上皮膜抗原(EMA)、S-100、HHF35和平滑肌肌动蛋白(SMA)等的表达。结果该肿瘤主要见于中老年男性皮下软组织或肌筋膜;主要分布在颈、背、肩及小腿,也可见于面部和足部。大体上边界清楚或有薄包膜,切面部分呈黏液样或胶冻状。该肿瘤在组织形态学上以成熟脂肪组织、增生的梭形细胞或星状细胞、黏液样及纤维化间质等为主要成分,在不同区域以不同的比例混杂构成。梭形细胞或星状细胞伸出细长分枝状胞质突起是其形态特征之一。无细胞异型性和核分裂象。此外,该肿瘤常有较丰富的丛状小血管和毛细血管,间质有肥大细胞、小淋巴细胞及浆细胞浸润。免疫组织化学染色梭形细胞显示CD34、bcl-2和波形蛋白强阳性,而HHF35、SMA和S-100阴性,肿瘤中所有成分对CK和EMA呈阴性反应。结论树突状纤维黏液脂肪瘤在临床表现、病理组织学改变以及免疫组织化学反应等方面有其独自的特点。该肿瘤似乎是介于梭形细胞脂肪瘤和软组织孤立性纤维性肿瘤的中间类型。需注意与黏液性脂肪肉瘤和黏液性恶性纤维组织细胞瘤鉴别诊断。该肿瘤生物学行为为良性,只需局部手术切除。     

肝脏单形性上皮样血管平滑肌脂肪瘤

目的：探讨肝脏单形性上皮样血管平滑肌脂肪瘤的临床病理学特征及诊断、鉴别诊断要点。方法：对1例单形性上皮样血管平滑肌脂肪瘤进行临床病理学分析及免疫组织化学研究。结果：肝脏单形性上皮样血管平滑肌脂肪瘤临床多无症状,光镜下单形性上皮样血管平滑肌脂肪瘤由形态多样的上皮样细胞构成,胞质透明或嗜酸,无脂肪组织及异常血管;免疫表型;HMB45阳性,SMA及vimentin部分阳性,desmin少数阳性,S－100蛋白弱阳性,cytokeratin及AFP阴性,CD34血管内皮细胞阳性。结论：肝脏单形性上皮样血管平滑肌脂肪瘤是极为罕见的间叶性肿瘤,组织起源至今不明,其诊断及鉴别诊断主要依靠病理组织学及免疫组织化学。     

伴脑膜上皮样漩涡和骨化生去分化脂肪肉瘤的临床病理分析

目的探讨伴脑膜上皮样漩涡和骨化生去分化脂肪肉瘤的临床特点、组织学特征、免疫表型、遗传学特点、诊断及鉴别诊断。方法回顾性分析1例伴脑膜上皮样漩涡和骨化生去分化脂肪肉瘤的临床资料、组织学特征、免疫表型和遗传学特点,并复习相关文献。结果伴脑膜上皮样漩涡和骨化生去分化脂肪肉瘤界限清楚,由硬化性脂肪肉瘤、脑膜上皮样漩涡状、骨化生和脂肪瘤样脂肪肉瘤等成分构成,脑膜上皮样漩涡状成分由上皮样细胞或梭形细胞呈漩涡状排列构成,与其它成分界限清楚。免疫表型:肿瘤细胞vimentin、MDM2、CDK4、p16、CD10和CD56均呈弥漫强阳性;CK、EMA、CD34、Caldesmon、PGP9.5和PR均呈阴性;S-100、Ki-67和p53在不同成分中表达不一致。遗传学检测显示MDM2扩增。结论伴脑膜上皮样漩涡和骨化生去分化脂肪肉瘤属于罕见的去分化脂肪肉瘤,脑膜上皮样漩涡状成分免疫表型和遗传学特点与其它脂肪肉瘤成分大致相同,提示漩涡状结构为去分化脂肪肉瘤的去分化成分,结合组织学特征、免疫表型和遗传学特点,可与其它具有漩涡状结构的肿瘤鉴别。     

前列腺特异性间质肉瘤2例报道并文献复习

目的 探讨前列腺特异性间质肉瘤(prostatic specialized stromal sarcoma,PSS)的临床病理学特点、免疫学表型、诊断和鉴别诊断要点.方法 通过常规HE染色及免疫组织化学标记,对2例PSS进行显微镜下组织学形态观察,并进行文献复习.结果 PSS细胞呈梭形及短梭形,呈束状、编织状、车辐状或弥漫性浸润生长,瘤细胞胞质丰富、嗜酸,细胞核主要呈卵圆形、短梭形,核仁不明显,可见较多增生且扩张的厚壁血管.免疫组化染色显示肿瘤细胞vimentin、CD34呈阳性表达,大部分病例PR阳性表达.结论 PSS是来源于前列腺激素依赖性特异性间质细胞的一种少见肉瘤.病理诊断主要依靠病理形态学和免疫组织化学标记,CD34和PR阳性是诊断该肿瘤的重要参考依据之一,鉴别诊断主要包括孤立性纤维性肿瘤/血管外皮细胞瘤、平滑肌肉瘤、横纹肌肉瘤、恶性外周神经鞘瘤等.     

梭形细胞/多形性脂肪瘤7例临床病理分析

目的探讨梭形细胞/多形性脂肪瘤(spindle cell/pleomorphic,SCL/PL)的临床病理学特征、诊断及鉴别诊断。方法回顾性分析7例SCL/PL的临床及病理学特征,并复习相关文献,并将其与脂肪瘤样型孤立性纤维性肿瘤、硬化型脂肪肉瘤、梭形细胞脂肪肉瘤进行对比分析。结果 7例患者年龄41~77岁,平均54岁,均为男性。肿瘤部位:手部2例,颈部3例,肩部2例。病史1~8年。梭形细胞脂肪瘤镜下由温和的梭形细胞、束状排列的胶原纤维及数量不等的脂肪细胞组成。多形性脂肪瘤可见特征性的大的、多形性、花环状细胞。免疫表型:梭形细胞及多形性细胞CD34阳性,脂肪细胞S-100阳性。术后随访5~59个月,未见复发及转移。结论 SCL/PL为较少见的良性肿瘤,应与一些良性、局部侵袭性及低度恶性的软组织肿瘤及肿瘤样病变相鉴别。     

寡脂肪及乏脂肪型梭形细胞脂肪瘤6例临床病理学分析

目的探讨寡脂肪及乏脂肪型梭形细胞脂肪瘤(LF-FFSCL)的临床病理学、免疫组织化学及分子遗传学特征和鉴别诊断要点。方法收集南京医科大学第一附属医院2014—2022年诊断的6例LF-FFSCL临床组织形态学特点及免疫组织化学结果, 对3例肿瘤组织采用荧光原位杂交(FISH)检测RB1基因的缺失状态, 复习相关文献进行分析。结果 6例患者中男性5例, 女性1例, 发病年龄34～68岁, 中位年龄56岁。发病部位情况:背部2例, 颈部、口腔、耳后及臀部各1例。4例肿瘤表现为皮下孤立界清无痛性结节, 1例位于真皮内, 1例位于舌下;镜下观察, 肿瘤主要由形态温和的梭形细胞组成, 呈无序或平行短束状排列, 肿瘤间质呈纤维或黏液状, 可见显著的绳索样胶原束和肥大细胞浸润;肿瘤内脂肪组织较少, 其中2例无脂肪成分, 其余4例脂肪成分均<5%。肿瘤内的梭形细胞弥漫强阳性表达CD34, RB1蛋白表达缺失, Ki-67阳性指数低;不表达S-100蛋白、SOX10、平滑肌肌动蛋白、STAT6、结蛋白、雌激素受体及上皮细胞膜抗原。分子病理检测显示RB1基因缺失。结论 LF-FFSCL是一种罕见的梭...     

原发于直肠伴炎性肌纤维母细胞肿瘤样特征的去分化脂肪肉瘤1例

伴炎性肌纤维母细胞肿瘤(inflammatory myofibroblastic tumor, IMT)样特征的去分化脂肪肉瘤(dedifferentiated liposarcoma, DDLPS)是一种罕见的以形态学类似IMT为特征的独特肿瘤。本文报道1例84岁女性患者原发于直肠的伴IMT样特征的DDLPS, 组织学形态显示肿瘤主要由高分化脂肪肉瘤和IMT样特征的去分化成分2种成分组成, 两者界限清楚, 去分化区域肿瘤细胞梭形、多边形, 束状或席纹状排列, 间质疏松水肿的炎性背景, 类似于IMT形态。免疫组织化学染色显示, 去分化与高分化脂肪肉瘤成分均弥漫阳性表达波形蛋白、MDM2和p16, Ki-67阳性指数约10%(高分化脂肪肉瘤区域)和25%(伴有IMT样特征的去分化区域);CD117、CD34、DOG1、间变性淋巴瘤激酶(ALK)-1、结蛋白和广谱细胞角蛋白均阴性。荧光原位杂交(FISH)检测显示高分化脂肪肉瘤和IMT样特征的去分化区域均存在MDM2基因簇状扩增, 而ALK-1基因重排阴性。具有IMT样特征的DDLPS与IMT相比, 其生物学行为更具侵袭性, 诊断除了免疫组...     

头皮低分化皮肤血管肉瘤的临床病理分析

目的 探讨头皮低分化皮肤血管肉瘤的临床免疫病理特征.方法 分析8例头皮低分化皮肤血管肉瘤患者的临床特点,观察其组织病理形态和CD31、CD34、第八因子相关抗原、波形蛋白、细胞角蛋白(AEl/AE3和CAM5.2)、上皮细胞膜抗原(EMA)、癌胚抗原(CEA)和S-100蛋白免疫组织化学染色.结果 患者平均发病年龄为69.0岁,男:女为5:3,临床早期常在头面部出现暗红斑,后期发生浸润性暗红斑块,均伴结节,偶发溃疡.组织病理检查示真皮广泛梭形细胞局部或广泛实性浸润,常见细胞异形,未见明确血管腔样结构.梭形细胞强阳性表达CD31、第八因子相关抗原和波形蛋白,弱阳性表达CD34、AEl/AE3和CAM5.2,而EMA、CEA和S-100蛋白阴性.结论 头面部出现淤斑样浸润性斑块和结节的老年患者,应及时做组织病理检查,CD31、CD34、第八因子相关抗原和波形蛋白免疫组织化学标记有助于明确诊断.     

Updates in spindle cell/pleomorphic lipomas

Spindle cell/pleomorphic lipomas are benign lipomatous neoplasms that show loss of RB1 and classically harbor components of mature adipose tissue, bland spindled cells and ropy collagen. This review highlights the clinicopathologic features and morphologic spectrum of spindle cell/pleomorphic lipoma, discusses an updated differential diagnosis, and provides a practical diagnostic strategy for spindle cell/pleomorphic lipomas with atypical clinical presentations.     

Atypical spindle cell lipoma: a clinicopathologic,immunohistochemical, and molecular study emphasizing its relationship to classical spindle cell lipoma

We studied a series of spindle cell lipomas arising in atypical sites and showing unusual morphologic features (which we called atypical spindle cell lipoma) to assess if these lesions have the same chromosomal alterations as classical spindle cell lipoma but different from those found in atypical lipomatous tumor/well-differentiated liposarcoma. We investigated alterations of different genes in the 13q14 region and the amplification status of the MDM2 and CDK4 genes at 12q14-15 by multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) analysis. In the atypical spindle cell lipomas, MLPA revealed deletions in the two nearest flanking genes of RB1 (ITM2B and RCBTB2) and in multiple important exons of RB1. In contrast, in classical spindle cell lipomas, a less complex loss of RB1 exons was found but no deletion of ITM2B and RCBTB2. Moreover, MLPA identified a deletion of the DLEU1 gene, a finding which has not been reported earlier. We propose an immunohistochemical panel for lipomatous tumors which comprises of MDM2, CDK4, p16, Rb, which we have found useful in discriminating between atypical or classical spindle cell lipomas and other adipocytic neoplasms, especially atypical lipomatous tumor/well-differentiated liposarcoma. Our findings strengthen the link between atypical spindle cell lipoma and classical spindle cell lipoma, and differentiate them from atypical lipomatous tumor/well-differentiated liposarcoma.     

Lipomatöse Tumoren der Haut und des Weichgewebes Neue Entitäten und Konzepte

Mesenchymal neoplasms of lipogenic differentiation are the most common soft-tissue neoplasms in adults. In recent years a number of "new" entities and variants have been described. Their recognition is important to avoid diagnostic pitfalls and inappropriate therapy. Chondroid lipoma, myolipoma, and purely cutaneous spindle-cell/pleomorphic lipoma are biologically benign neoplasms which may mimic sarcomas morphologically. Despite high-grade morphology cutaneous liposarcomas carry a favorable clinical prognosis. Spindle cell liposarcoma is a rare variant of atypical lipomatous tumour (well-differentiated liposarcoma) and must be distinguished from dedifferentiated liposarcoma with metastatic potential and benign spindle cell lipoma. The advent of cytogenetic and molecular investigations of lipomatous neoplasms has contributed to a better understanding of the biology of these neoplasms and led to a modification of conventional classification schemes.     

Sensitivity of MDM2 amplification and unexpected multiple faint alphoid 12 (alpha 12 satellite sequences) signals in atypical lipomatous tumor

This study assessed whether analysis of MDM2 copy number by fluorescence in situ hybridization (FISH) would help distinguish lipomas from atypical lipomatous tumors, otherwise referred to as well-differentiated liposarcomas, using a commercially available MDM2 FISH kit. 227 lipomatous and 201 non-lipomatous tumors were analyzed to assess its sensitivity and specificity. Of 178 mature lipomatous tumors, 86 were classified histologically as lipoma and 92 as atypical lipomatous tumor. Two of the lipomas harboring MDM2 amplification were reclassified as atypical lipomatous tumors. Overall, 13 atypical lipomatous tumors did not reveal MDM2 or CDK4 amplification, although this was reduced to 12 following analysis of multiple slides. Three of these cases revealed very occasional tumor cells harboring high-level MDM2 amplification, two had a dedifferentiated component, and MDM2 amplification was detected when one tumor recurred. The remaining six cases exhibited reactive/inflammatory features and were reclassified as lipomas. The findings indicate that MDM2 amplification is 93.5% sensitive for diagnosing atypical lipomatous tumor. A total of 2 of the 20 dedifferentiated liposarcomas failed to reveal MDM2 amplification. All atypical lipomatous tumors measured >10?cm, two dedifferentiated liposarcoma presented de novo at <10?cm, and ～50% of lipomas measured >10?cm. Spindle cell lipomas, lipoblastomas, hibernomas and pleomorphic liposarcomas did not reveal MDM2 amplification. Of 201 non-lipomatous tumors, eight revealed MDM2 amplification or multiple faint alphoid 12 signals and were reclassified as dedifferentiated liposarcoma. Multiple faint alphoid 12 signals were observed in nine tumors from seven patients, an observation not previously reported on paraffin sections: these included four atypical lipomatous tumors, and three dedifferentiated liposarcomas, one previously diagnosed as a myxofibrosarcoma, all of which also revealed amplification of CDK4, although two lacked MDM2 amplification. MDM2 FISH test is a useful adjunct to histology for distinguishing lipoma from atypical lipomatous tumor. The limitations of molecular genetic tests must be known before introducing them into a clinical service.     

Angiomyofibroblastoma-like tumor (lipomatous variant) of the inguinal region of a male patient

A case of angiomyofibroblastoma-like tumor (lipomatous variant) that arose in the subcutis of the inguinal region of a 45-year-old man is presented. The maximum dimension of the tumor measured 39 mm and it was well circumscribed. Histopathological examination revealed a close admixture of plump spindle or stellate cells and mature adipocytes. These were arranged haphazardly or formed interconnecting thin cellular trabeculae on the myxoid or edematous background. The tumor was highly vascularized and contained a moderate amount of collagen fibers. Immunohistochemically, the tumor cells were positive for vimentin, CD34 and the estrogen receptor, but negative for alpha-smooth muscle actin and desmin. The differential diagnosis between the lipomatous variant of angiomyofibroblastoma and cellular angiofibroma or spindle cell lipoma is discussed, and the pathogenetic hypotheses about the occurrence of mature adipocytes within benign fibroblastic or myofibroblastic neoplasms are mentioned briefly. It is important for surgical pathologists to be acquainted with the occasional presence of adipocytes in these neoplasms to avoid misinterpretation.     

Desmin expression in spindle cell lipomas: a potential diagnostic pitfall

The immunohistochemical analysis of the spindle cell lipomas has been for the most part limited to the study of S-100 protein, CD34, and Bcl-2 reactivity. To evaluate the immunoexpression of desmin and actins in spindle cell lipomas of different histological subtypes a retrospective immunohistochemical study of 25 spindle cell lipomas using archival formalin-fixed, paraffin-embedded tissue was performed. Strong positivity of the spindle cell component for desmin was found in 4 of 25 cases (16%). The expression was diffuse in two cases and focal (in up to 25% of the spindle cells) in the other two. Two of these cases were of the classical type and the other two were angiomatous spindle cell lipomas. Desmin-positive and desmin-negative spindle cells showed no morphological differences. The spindle cell component expressed CD34 in all cases and Bcl-2 in 14 of the 25 cases. There was no immunoreactivity for smooth muscle actin, muscle-specific actin, or S-100 protein. We conclude that a significant proportion of spindle cell lipomas express desmin, and therefore that the immunoreactivity for this antigen does not exclude the diagnosis, even in lesions with nonclassical histological features and/or atypical locations.     

Multiple spindle cell lipomas of the tongue: report of a case

Spindle cell lipoma (SCL) is a relatively uncommon benign lipomatous tumor characterized by a mixture of mature adipocytes and bland spindle cells on a fibromyxoid background. These lipomas usually arise as solitary nodules in the subcutaneous tissue of the posterior neck, shoulder and back in adult men. Multiple SCLs account for 0.5% to 3% of all SCLs. In the literature, there have been 15 cases of intraoral SCL, including 6 cases of SCL in the tongue. We report a case of multiple SCLs on the bilateral margins of the tongue of a 75-year-old Japanese man. The tumors were removed surgically, and they exhibited the classic histopathological features of SCL, being well-circumscribed masses composed of a mixture of adipocytes and fibroblast-like spindle cells within a fibromyxoid stroma. Immunohistochemical analysis revealed that the spindle cells were strongly positive for CD 34 and bcl-2. To our knowledge, this is the first report of a case of multiple SCLs of the tongue.     

Aspiration cytology of lipomatous tumors: A 10-year experience at an orthopedic oncology center

The cytodiagnoses of preoperative fine-needle aspirate smears from 72 histologically proven lipomatous tumors (52 lipomas and 20 liposarcomas of varying type) collected during the 10-yr period 1972–1981 were correlated to the corresponding histopathologic diagnoses. Three out of 52 lipomas were erroneously diagnosed as low-grade malignant liposarcomas, and one out of 20 liposarcomas was falsely diagnosed as a benign soft-tissue tumor. Of the 20 liposarcomas, 15 were cytologically diagnosed as such, and the majority of the myxoid and the pleomorphic liposarcomas were correctly diagnosed as to type. Important differential diagnostic problems were, on one hand, the separation of lipoma with regressive changes and histiocytic reaction and lipoma with chondroid metaplasia from low-grade malignant liposarcoma and, on the other hand, liposarcoma from intramuscular myxoma, myxofibrosarcoma, and malignant fibrous histiocytoma. The differential diagnosis of liposarcoma as opposed to other soft-tissue sarcomas is discussed, and it is concluded that preoperative fine-needle aspiration of lipomatous tumors is of value in the management of these tumors. Diagn Cytopathol 1987;3:295–302.     

Desmin‐positivity in spindle cells: Under‐recognized immunophenotype of lipoblastoma

Lipoblastoma is a distinct benign fatty tumor composed of adipocytes, lipoblasts, and primitive mesenchymal cells with a myxoid stroma. Lipoblastoma harbors characteristic fusion genes involving the PLAG1, resulting in aberrant expression of PLAG1. However, the nature of the primitive mesenchymal cells remains obscure. In our routine pathology practice, we noticed desmin‐positive spindle mesenchymal cells in lipoblastomas, which is a hitherto poorly described phenomenon. Thus, we examined the expression of several myogenic markers including desmin in a variety of 95 mesenchymal tumors with fatty elements. Fourteen of the 15 lipoblastomas examined contained desmin‐positive spindle cells, which also showed nuclear expression of PLAG1, whereas α‐smooth muscle actin, muscle specific actin, h‐caldesmon, and myogenin were negative. Some spindle cells in subsets of atypical lipomatous tumors/well differentiated liposarcomas (6/20), dedifferentiated liposarcomas (11/31) and pleomorphic liposarcomas (2/10) were positive for actins and/or desmin, supporting focal myofibroblastic or smooth muscle differentiation. The other tumors, including 11 myxoid/round cell liposarcomas, four spindle cell lipomas, and four lipofibromatoses, were negative for all of the myogenic markers assessed. The almost consistent desmin expression in spindle mesenchymal cells suggests a potential diagnostic utility of this marker and myofibroblastic phenotype of fractions in lipoblastoma cells.     

Cutaneous lipomatous neoplasms.

Benign and malignant lipomatous tumors are the most common neoplasms of subcutaneous and deep soft tissues in adults. In contrast, purely cutaneous lipogenic neoplasms are exceptionally rare, and some entities and variants of adipocytic neoplasms have not yet been described in the skin. In addition, some dermal lipogenic neoplasms are characterized by different specific clinicopathologic features in comparison with more deeply located tumors. Cutaneous angiolipoleiomyoma ("angiomyolipoma") is seen most often in male patients and in an acral location. It is characterized histologically by mature adipocytes, thick-walled blood vessels, and smooth muscle cells arranged in well-defined fascicles and around blood vessels. Smooth muscle cells in cutaneous angiolipoleiomyoma stain negatively for HMB-45, in contrast to renal and extrarenal angiomyolipoma. Adenolipoma of the skin is a superficially located form of lipoma composed of large lobules of mature adipocytic tissue admixed with eccrine ducts and glands. Cutaneous spindle cell/pleomorphic lipomas, in contrast to subcutaneous forms, are more common in female patients and have a wide anatomic distribution. Histologically, cutaneous spindle cell/pleomorphic lipomas are characterized by an infiltrative growth pattern mimicking more aggressive lesions. Rarely, liposarcoma may occur as a purely cutaneous lesion with a favorable clinical prognosis despite high-grade morphologic features in many cases.