Pericytic mimicry in well-differentiated liposarcoma/atypical lipomatous tumor

We report the case of a “fat-rich” (spindle cell-poor) variant of an atypical spindle cell/pleomorphic lipomatous tumor in a 63-year-old female patient presenting with a firm, painless soft tissue mass on the right hip. Atypical spindle cell/pleomorphic lipomatous tumor is a very recently described low-grade adipocytic neoplasm, which occurs predominantly in adults with a predilection for the limbs and limb girdles. In the present case, the diagnosis of an atypical spindle cell/pleomorphic lipomatous tumor was challenging because the tumor was almost exclusively composed of an atypical adipocytic component (resembling “classical” atypical lipomatous tumor/well-differentiated tumor) with only very focal presence of the diagnostic atypical morphologic features (atypical spindle-shaped cells, floret-like multinucleated cells, and “bizarre” pleomorphic [multinucleated] cells). The possibility of a “classical” atypical lipomatous tumor/well-differentiated liposarcoma was ruled out by immunohistochemistry (lack of MDM2 expression and loss of Rb expression) and molecular genetic testing (no amplification of MDM2 and presence of monoallelic deletion of RB1). Another interesting morphologic observation in this case was the striking perivascular location of the atypical spindle/pleomorphic cells in some areas (so-called “pericytic mimicry”). To our knowledge, pericytic mimicry has not been reported in the setting of an atypical spindle cell/pleomorphic lipomatous tumor.

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Orbital Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma Masquerading as Pleomorphic Lipoma

Ophthalmic Plastic and Reconstructive Surgery ◽

10.1097/iop.0000000000001378 ◽

2019 ◽

Vol 35 (3) ◽

pp. e76-e80 ◽

Cited By ~ 1

Author(s):

Kyle McKey ◽

Paul J. L. Zhang ◽

Carol L. Shields ◽

Sara E. Lally ◽

Ralph C. Eagle ◽

...

Keyword(s):

Atypical Lipomatous Tumor ◽

Lipomatous Tumor ◽

Pleomorphic Lipoma ◽

Well Differentiated

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Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma of the Gingiva: A Case Report and Review of Literature

Journal of Oral and Maxillofacial Surgery ◽

10.1016/j.joms.2013.06.222 ◽

2014 ◽

Vol 72 (2) ◽

pp. 431-439 ◽

Cited By ~ 12

Author(s):

Young Bin Kim ◽

Dae Ho Leem ◽

Jin A. Baek ◽

Seung O. Ko

Keyword(s):

Case Report ◽

Review Of Literature ◽

Atypical Lipomatous Tumor ◽

Lipomatous Tumor ◽

Well Differentiated

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A Retrospective Study of Superficial Type Atypical Lipomatous Tumor

Frontiers in Medicine ◽

10.3389/fmed.2020.609515 ◽

2020 ◽

Vol 7 ◽

Author(s):

Emi Mashima ◽

Yu Sawada ◽

Natsuko Saito-Sasaki ◽

Kayo Yamamoto ◽

Shun Ohmori ◽

...

Keyword(s):

Surgical Resection ◽

Tumor Size ◽

Clinical Characteristics ◽

Clinical Manifestations ◽

Tumor Location ◽

Atypical Lipomatous Tumor ◽

Lipomatous Tumor ◽

Physical Examinations ◽

Superficial Type ◽

Well Differentiated

Atypical lipomatous tumor (ALT) has been defined as a well-differentiated liposarcoma exhibiting a higher frequency of a local recurrence after surgical resection. ALT is mainly classified into deep type and superficial type. Compared with deep type ALT, superficial type ALT is rarely observed. One of the most important issues is that little has been known about superficial type ALT and it is not easy to predict the presence of superficial type ALT before surgical resection. To clarify the clinical manifestations of superficial type ALT, we examined 15 cases with superficial type ALT and 118 cases with benign lipoma, and analyzed their differences in clinical characteristics and the findings of MRI test. In clinical characteristics, the tumor size of superficial type ALT was significantly greater than that of benign lipoma, and superficial type ALT showed a significantly higher frequency of the tumor size of more than 4 cm. Superficial type ALT exhibited poor tumor mobility and hardness with elastic soft. In addition, a significantly higher frequency of tumor location of superficial type ALT was observed in extremities. Among tumor sites at the trunk, buttocks, and shoulder were high frequent location in superficial type ALT. In an MRI examination, superficial type ALT exhibited a significantly higher frequency of the septal structures compared with benign lipoma. The combinations of clinical characteristics, including physical examinations, MRI, and histological examinations, are helpful for the diagnosis of superficial type ALT.

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