Atypical mitoses in pleomorphic lipomas

Babaoğlu, Berrin; Kazakov, Dmitry V.; Michał,; Kösemehmetoğlu, Kemal

doi:10.1016/j.humpath.2017.06.024

Cited by 10 publications

(4 citation statements)

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“…Regarding the literature for these atypical, pleomorphic tumors with RB loss, the terminology has been a source of confusion for the past few decades. They have been characterized as low-grade pleomorphic adipocytic neoplasms with atypical morphologic features in some reports, 15,16 while others have proposed the classification as spindle cell liposarcoma and fibrosarcoma-like lipomatous neoplasm. 17 Classification as a sarcoma has mostly been discouraged as they seem to behave in an indolent manner.…”

Section: Discussionmentioning

confidence: 99%

“…Among the variable terminology in this spectrum of tumors, the term ASPLT has now been favored and included in the 2020 WHO classification to describe these low-grade pleomorphic adipocytic neoplasms with a pleomorphic lipoma-like appearance and atypical morphologic features with rare aggressive behavior. 9,11,15,16 This group of tumors reported as ASPLT is mostly located in subcutis and exhibits lipomatous differentiation. We believe our series of tumors that are mostly dermal-based with mostly…”

Section: Discussionmentioning

confidence: 99%

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Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas

et al. 2022

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Background: Spindle cell lipomas, pleomorphic lipomas (SCL/PLs), and pleomorphic fibromas (PF) are tumors with loss of retinoblastoma (RB). The latest World Health Organization classification includes a category of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT), which encompasses tumors in this spectrum that show atypical histopathologic features. We have observed PFs that show similar atypical features.Methods: Cases of SCL/PL and PF with atypical features were collected from tissue archives between 2010 and 2019. Genetic alterations were investigated using array comparative genomic hybridization (aCGH).Result: Of 15 cases found, most tumors were dermal based with fibrocytic or fibroadipocytic appearance and occasional lipoblasts. All cases had a high proliferation index with atypical mitotic figures in 71% of cases. Chromosome 13q loss was present in all cases with CGH data. Additional recurrent chromosomal losses included 17p, 16q, 17q, 20p, 4, and 10. No recurrence was found in limited follow-up.Conclusions: ASPLTs are characterized by loss of RB, prominent nuclear pleomorphism, mitotic activity including atypical mitotic figures, and genomic instability with multiple chromosomal aberrations. A similar group of tumors with these histopathologic features lacks lipomatous differentiation, and we propose the diagnosis of atypical PF as a fibromatous variant of ASPLT. Limited clinical follow-up appears benign.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas

et al. 2022

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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%

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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Spindle Cell Lipoma/Pleomorphic Lipoma

Rekhi

2019

Encyclopedia of Pathology

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Spindle cell/pleomorphic lipoma, together represent a morphological continuum, mostly occur in the neck and upper trunk of older males and are histopathologically characterized by relatively bland spindle cells, admixed with mature adipose tissue, along with variable myxoid stroma, ropey collagen, and pleomorphic, multinucleate giant cells, the latter feature pronounced in the pleomorphic lipoma. These tumors are invariably immunoreactive for CD34.

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Atypical mitoses in pleomorphic lipomas

Cited by 10 publications

References 1 publication

Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas

Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas

Atypical Pleomorphic Lipomatous Tumor

Spindle Cell Lipoma/Pleomorphic Lipoma

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