Low-Fat and Fat-Free Pleomorphic Lipomas: A Diagnostic Challenge

Sachdeva, Mandi; Goldblum, John R.; Rubin, Brian P.; Billings, Steven D.

doi:10.1097/dad.0b013e3181a129b7

Cited by 32 publications

(25 citation statements)

References 22 publications

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“…Although the histopathological features suggested the diagnosis of pleomorphic lipoma, it remained challenging because of the lack of a fat component. Recently, Sachdeva [11] and Billings [18] reported the ‘low-fat’ and ‘fat-free’ variants of pleomorphic lipoma and spindle cell lipoma, respectively. Meanwhile, they proposed that the key to the diagnosis of such variants lies in the nonlipogenic component rather than the lipogenic component.…”

Section: Discussionmentioning

confidence: 99%

“…In such instances, the border between pleomorphic lipoma and atypical lipomatous tumor is blurred. In addition, the amount of mature fat in pleomorphic lipoma is variable [10,11], which poses a great diagnostic challenge in cases with little to no fat. Immunohistochemically, pleomorphic lipoma is strongly positive for CD34, but negative for S100 protein and smooth muscle actin (SMA) [1].…”

Section: Introductionmentioning

confidence: 99%

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A case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously

et al. 2013

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Pleomorphic lipoma is a rare neoplasm that predominantly occurs in the dermis or subcutis of the posterior neck, upper back, and shoulders. Although pleomorphic lipoma is a benign tumor, it may contain atypical cells. As a variant of spindle cell lipoma, pleomorphic lipoma clinically presents as a slow-growing and well-circumscribed subcutaneous mass. Rarely, some patients have multiple lesions. Histologically, pleomorphic lipoma is composed of mature fat, bland spindle-shaped mesenchymal cells, and coarse ‘rope-like’ collagen bands. In addition, lipoma contains multinucleated floret-like giant cells. Although spindle cell lipoma/pleomorphic lipoma with little fat was seen in the original series described by Enzinger and Harvey, cases with little to no fat remain diagnostically challenging. Herein, we report a case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously. Although the lipoma was typically composed of bland spindle-shaped cells, rope-like collagen, scattered floret-like giant cells, and striking stromal myxoid change in the background, mature fat was absent. Immunohistochemical analyses showed positive staining for CD34, vimentin, and Bcl-2, and negative staining for S100, confirming the diagnosis of pleomorphic lipoma.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously

et al. 2013

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“…Immunohistochemically, the spindle cells and “floret-like” cells are strongly positive for CD34, but negative for S-100 protein and smooth muscle actin [4,5]. Some cases can show desmin positive expression, which may lead to a misdiagnosis of a smooth muscle tumor [17]. …”

Section: Discussionmentioning

confidence: 99%

Pleomorphic lipoma lacking mature fat component in extensive myxoid stroma: a great diagnostic challenge

et al. 2012

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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.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1967123180611361

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“…According to the World Health Organization and others, liposarcoma is currently subclassified into four groups: well differentiated, dedifferentiated, myxoid/round cell, and pleomorphic [4], [5]. In contrast, lipoma is a benign tumor which is composed of adipose tissue and is the most common form of soft tissue tumor [6], [7]. Although some genetic studies have provided insight into the mechanism of liposarcoma and lipoma development, the exact pathogenesis remains largely unknown [8]–[10].…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of Targeted PI3K Signaling Inhibition and Chemotherapy in Liposarcoma

et al. 2014

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While liposarcoma is the second most common soft tissue malignant tumor, the molecular pathogenesis in this malignancy is poorly understood. Our goal was therefore to expand the understanding of molecular mechanisms that drive liposarcoma and identify therapeutically-susceptible genetic alterations. We studied a cohort of high-grade liposarcomas and benign lipomas across multiple disease sites, as well as two liposarcoma cell lines, using multiplexed mutational analysis. Nucleic acids extracted from diagnostic patient tissue were simultaneously interrogated for 150 common mutations across 15 essential cancer genes using a clinically-validated platform for cancer genotyping. Western blot analysis was implemented to detect activation of downstream pathways. Liposarcoma cell lines were used to determine the effects of PI3K targeted drug treatment with or without chemotherapy. We identified mutations in the PIK3CA gene in 4 of 18 human liposarcoma patients (22%). No PIK3CA mutations were identified in benign lipomas. Western blot analysis confirmed downstream activation of AKT in both PIK3CA mutant and non-mutant liposarcoma samples. PI-103, a dual PI3K/mTOR inhibitor, effectively inhibited the activation of the PI3K/AKT in liposarcoma cell lines and induced apoptosis. Importantly, combination with PI-103 treatment strongly synergized the growth-inhibitory effects of the chemotherapy drugs doxorubicin and cisplatin in liposarcoma cells. Taken together, these findings suggest that activation of the PI3K/AKT pathway is an important cancer mechanism in liposarcoma. Targeting the PI3K/AKT/pathway with small molecule inhibitors in combination with chemotherapy could be exploited as a novel strategy in the treatment of liposarcoma.

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Low-Fat and Fat-Free Pleomorphic Lipomas: A Diagnostic Challenge

Cited by 32 publications

References 22 publications

A case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously

A case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously

Pleomorphic lipoma lacking mature fat component in extensive myxoid stroma: a great diagnostic challenge

Synergistic Effects of Targeted PI3K Signaling Inhibition and Chemotherapy in Liposarcoma

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