Atypical mitoses are present in otherwise classical pleomorphic lipomas

Babaoğlu, Berrin; Erçin, Mustafa Emre; Kösemehmetoğlu, Kemal

doi:10.1016/j.humpath.2018.04.033

Cited by 2 publications

(2 citation statements)

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“…Some authors have claimed that atypical features, such as atypical mitoses, pleomorphic lipoblasts, and infiltrative growth may be permissible in pleomorphic lipoma, and additionally expressed concern that a diagnosis of APLT may lead to overtreatment. [21][22][23][24] This opinion was mostly maintained by the fact that tumors with these atypical features were also either located in a "classic" anatomic site for pleomorphic lipoma or did not recur after long-term follow-up. However, the latter 2 findings can both be true for cases of APLT.…”

Section: Discussionmentioning

confidence: 99%

“…Nonetheless, some uncertainties regarding classification remain given the morphologic overlap between spindle cell/pleomorphic lipoma and ASCLT/APLT. Some authors have claimed that atypical features, such as atypical mitoses, pleomorphic lipoblasts, and infiltrative growth may be permissible in pleomorphic lipoma, and additionally expressed concern that a diagnosis of APLT may lead to overtreatment 21–24. This opinion was mostly maintained by the fact that tumors with these atypical features were also either located in a “classic” anatomic site for pleomorphic lipoma or did not recur after long-term follow-up.…”

Section: Discussionmentioning

confidence: 99%

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Atypical Pleomorphic Lipomatous Tumor

Anderson

Fletcher

2021

American Journal of Surgical Pathology

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Atypical pleomorphic lipomatous tumor (APLT) is a recently recognized adipocytic neoplasm that lies on a spectrum with atypical spindle cell lipomatous tumor (ASCLT). APLT/ASCLT are included together in the fifth edition World Health Organization Classification of Soft Tissue and Bone Tumours; however limited data on APLT have emerged since its first description in 2017. This study aims to further define the clinicopathologic features of APLT in a large series of 64 cases. Histologic features and ancillary studies were reviewed, and clinical and follow-up data were obtained from referring institutions. Immunohistochemistry for MDM2, CDK4, CD34, Rb, S100, and desmin was performed in cases with available material. Patients were 24 females and 40 males, and the median age was 61 years (range, 20 to 89 y). Tumors arose in upper limb (33%), lower limb (31%), trunk (23%), head and neck (8%), breast (3%), and inguinal region (2%), with a median size of 5.4 cm (range, 1.5 to 14.5 cm). Tumor depth was mostly subcutaneous or deep/subfascial. Microscopically, APLTs were variably composed of atypical spindle and pleomorphic cells, adipocytes, and lipoblasts, often showing infiltrative growth, myxoid or collagenous stroma, and multinucleate floret cells. Mitoses were infrequent and necrosis was consistently absent. By immunohistochemistry, tumors expressed CD34 (63%), S100 (19%), and desmin (28%). APLT showed frequent loss of Rb (79%; 46/58). Rare cases showed staining for MDM2 (2%) or CDK4 (12%); however, fluorescence in situ hybridization was negative for MDM2 amplification in all cases tested (0/22). Follow-up in 28 patients (median duration: 21 mo) revealed a single patient with local recurrence (4%); no patient developed metastatic disease. Despite its frequently infiltrative growth, nuclear pleomorphism, and hypercellularity which can mimic sarcoma, APLT behaves in an indolent manner and should be distinguished from its more aggressive mimics, including atypical lipomatous tumor/well-differentiated liposarcoma and pleomorphic liposarcoma. Immunohistochemistry for CD34, S100, desmin, and Rb (demonstrating loss), as well as exclusion of MDM2 amplification, can support the diagnosis.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Atypical Pleomorphic Lipomatous Tumor

Anderson

Fletcher

2021

American Journal of Surgical Pathology

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A Reappraisal of Superficial Pleomorphic Liposarcoma

Berg

Massoud

Jackson‐Cook

et al. 2020

American Journal of Clinical Pathology

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Objectives Superficial pleomorphic liposarcoma (PL) has a favorable prognosis compared to deeply seated PL. Given developments in the classification of lipomatous neoplasms, we reappraised a series of cases. Methods Retrospective clinicopathologic evaluation and genome-wide single-nucleotide polymorphism (SNP) microarray studies were performed for cases previously designated superficial PL. Results Four cases were identified (age, 48-70 years). Two were dermally confined, whereas two were superficial subcutaneous; no recurrences or metastases were reported. Tumors demonstrated pleomorphic spindled morphology with variable cellularity. Multivacuolated atypical lipoblasts were focal in 3 and abundant in 1. Dermal tumors demonstrated atypical cells within sclerotic collagen. Genome-wide SNP microarray studies revealed consistent gains and losses, including losses at the 13q14.2 locus encompassing RB1 and DLEU2 and deletion/disruption of the TP53 locus. Although subcutaneous examples showed genomic changes similar to deep PL, the dermal examples showed fewer genetic alterations, including changes reported in the spectrum of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT). All lacked MDM2 amplification. Conclusions Careful integration of histologic and genetic features may improve classification of lipomatous neoplasms with atypia, allowing reclassification of some superficial PL as ASPLT.

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Atypical mitoses are present in otherwise classical pleomorphic lipomas

Cited by 2 publications

References 5 publications

Atypical Pleomorphic Lipomatous Tumor

Atypical Pleomorphic Lipomatous Tumor

A Reappraisal of Superficial Pleomorphic Liposarcoma

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