<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Liposarcomas are malignant mesenchymal neoplasms that, although derived from adipocytes, may dedifferentiate to other cell types. We present an exceedingly rare case of epithelioid/neuroendocrine dedifferentiation with somatostatin expression of a pararenal retroperitoneal liposarcoma.</p>
<p>Based on the immunomorphological features, the diagnosis was possible with the support of the molecular FISH investigation: it showed amplification of the MDM2 gene, which is present in most liposarcomas, even in dedifferentiated ones.</p>
</abstract>

Liposarcomas are malignant mesenchymal neoplasms that, although derived from adipocytes, may dedifferentiate to other cell types. We present an exceedingly rare case of epithelioid/neuroendocrine dedifferentiation with somatostatin expression of a pararenal retroperitoneal liposarcoma.
Based on the immunomorphological features, the diagnosis was possible with the support of the molecular FISH investigation: it showed amplification of the MDM2 gene, which is present in most liposarcomas, even in dedifferentiated ones.


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<sec id="j_fco-2022-0007_s_001"><div>Dear Editor-in-Chief</div>
<p>We have read with interest the article entitled ‘Gastrointestinal Neuroendocrine Tumours: A Single-Centre Experience’, published in Forum of Clinical Oncology<sup>[<a ref-type="bibr" href="#j_fco-2022-0007_ref_001">1</a>]</sup>.</p>
<p>We would like to point out, however, that not all intra-abdominal lesions with neuroendocrine phenotypic expression are gastro-entero-hepato-pancreatic neuroendocrine epithelial neoplasms.</p>
<p>We present the case of a woman in her sixties with a pararenal mass 12 cm in diameter, radiologically doubtful as to being of renal origin or from the pancreatic tail: surgery revealed that this mass was extra-renal and extra-pancreatic, thus sparing both organs.</p>
<p>Histology showed an epithelioid nested neoplasia, with necrosis and several mitoses (<a ref-type="fig" href="#j_fco-2022-0007_fig_001">Fig. 1A</a>); notably, spindle cell and adipocytic areas with cytological atypia are observed on the surrounding border (<a ref-type="fig" href="#j_fco-2022-0007_fig_001">Fig. 1B</a>). Immunohistochemistry results were the following: cytokeratins−; chromogranin−; synaptophysin−; NSE+ (<a ref-type="fig" href="#j_fco-2022-0007_fig_001">Fig. 1C</a>); CD56+; somatostatin+ (<a ref-type="fig" href="#j_fco-2022-0007_fig_001">Fig. 1D</a>); insulin−; glucagon−; gastrin−; serotonin−; pancreatic polypeptide−; pS100−; SOX10−; melan A−; HMB45−; vimentin−/+; CD31−; CD34−; FLI1−; desmin−; smooth muscle actin −/+; muscle specific actin−; CD117−; DOG1−; inhibin−; MUC1−; tyrosinase−; GATA3−; CD99−; BCL2+; WT1−.</p>
<figure id="j_fco-2022-0007_fig_001" position="float" fig-type="figure"><h2>Figure 1:</h2>
<figCaption><p>Photomicrographs of liposarcoma with epithelioid/neuroendocrine dedifferentiation: A) histological view of a neoplasm organised in nests separated by thin fibrovascular branches, cytologically of epithelioid appearance (Hematoxilin and Eosin, 20×); B) at higher magnification, spindle/elongated neoplastic elements, also with mitosis (arrow), are observed at the edges of the epithelioid neoplasm, suggesting a possible mesenchymal origin (Hematoxilin and Eosin, 40×); C) immunohistochemistry for NSE, showing positivity in scattered neoplastic cells (10×); D) immunohistochemistry for somatostatin, showing ‹dot like› positivity in epithelioid neoplastic cells (10×).</p></figCaption>
<img xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_fco-2022-0007_fig_001.jpg" src="https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64cbc5f9b675be7e8f4124cd/j_fco-2022-0007_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Date=20240620T043958Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=18000&amp;X-Amz-Credential=AKIA6AP2G7AKP25APDM2%2F20240620%2Feu-central-1%2Fs3%2Faws4_request&amp;X-Amz-Signature=e76e2ef57323cdfcf7037613e0a3c049d03289ec7a9fc877f670887959de5041" class="mw-100"/>
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<p>The findings led us to a malignant neoplasm with neuroendocrine expression (NSE, somatostatin, CD56), whose true nature was, however, difficult to define: the epithelioid morphology found does not allow us to define an epithelial origin; furthermore, neuroendocrine tumours are cytokeratin-negative only rarely.</p>
<p>The following were considered in the differential diagnosis: pancreatic or gastro-enteric neuroendocrine tumour, paraganglioma, adrenal carcinoma, GIST, PEComa, schwannoma<sup>[<a ref-type="bibr" href="#j_fco-2022-0007_ref_002">2</a>]</sup>, and melanoma, but they are excluded by immunohistochemistry results.</p>
<p>The positivities for vimentin and actin, although in rare neoplastic elements, led to the suspicion of a mesenchymal nature, and the atypical features in the surrounding fibroadipose tissue reinforced this hypothesis: we therefore proceeded with the assessment of <italic>MDM2</italic> gene amplification by <italic>FISH</italic>. The result was: amplified (<a ref-type="fig" href="#j_fco-2022-0007_fig_002">Fig. 2</a>).</p>
<figure id="j_fco-2022-0007_fig_002" position="float" fig-type="figure"><h2>Figure 2:</h2>
<figCaption><p>FISH photomicrograph showing a liposarcoma tissue section with amplification of the MDM2 gene (green signal), compared to the control CEN 12 (orange signal).</p></figCaption>
<img xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_fco-2022-0007_fig_002.jpg" src="https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64cbc5f9b675be7e8f4124cd/j_fco-2022-0007_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Date=20240620T043958Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=18000&amp;X-Amz-Credential=AKIA6AP2G7AKP25APDM2%2F20240620%2Feu-central-1%2Fs3%2Faws4_request&amp;X-Amz-Signature=5a2dc8c966a1484443df551ade4847c854239fbc94d829b9c5c7b141f65bd4a8" class="mw-100"/>
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<p>Pararenal malignancies may originate from the renal capsule or the adrenal gland<sup>[<a ref-type="bibr" href="#j_fco-2022-0007_ref_003">3</a>,<a ref-type="bibr" href="#j_fco-2022-0007_ref_004">4</a>]</sup>; however, more frequently, they arise from the retroperitoneal soft tissues: the most frequent is liposarcoma. Such a neoplasm derives from adipocytes but can dedifferentiate to many histological lines: the epithelioid/neuroendocrine is one of the rarest<sup>[<a ref-type="bibr" href="#j_fco-2022-0007_ref_005">5</a>]</sup>. In any case, the vast majority of liposarcomas, even dedifferentiated ones, show amplification of the MDM2 gene.</p>
<p>It is therefore thanks to the above FISH result that it was possible to label this lesion as a liposarcoma, although exceptionally rare in this form of epithelioid/neuroendocrine dedifferentiation with somatostatin expression<sup>[<a ref-type="bibr" href="#j_fco-2022-0007_ref_006">6</a>]</sup>.</p>
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Retroperitoneal pararenal dedifferentiated liposarcoma with epithelioid/neuroendocrine features, somatostatin-positive.

Scuola di Scienze Mediche e Farmaceutiche, Department of Integrated Surgical and Diagnostic Sciences (DISC), Division of Anatomic Pathology

Forum of Clinical Oncology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Liposarcomas are malignant mesenchymal neoplasms that, although derived from adipocytes, may dedifferentiate to other cell types. We present an exceedingly...

Retroperitoneal pararenal dedifferentiated liposarcoma with epithelioid/neuroendocrine features, somatostatin-positive.

Article Category: Research Article

Published Online: Aug 03, 2023

Page range: 63 - 65

Received: Nov 13, 2022

Accepted: Jan 04, 2023

DOI: https://doi.org/10.2478/fco-2022-0007

Keywords
liposarcoma, dedifferentiated, epithelioid, neuroendocrine, somatostatin, MDM2

© 2022 Gabriele Gaggero et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Retroperitoneal pararenal dedifferentiated liposarcoma with epithelioid/neuroendocrine features, somatostatin-positive.

Article Category: Research Article

Published Online: Aug 03, 2023

Page range: 63 - 65

Received: Nov 13, 2022

Accepted: Jan 04, 2023

DOI: https://doi.org/10.2478/fco-2022-0007

Keywordsliposarcoma, dedifferentiated, epithelioid, neuroendocrine, somatostatin, MDM2

© 2022 Gabriele Gaggero et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
liposarcoma, dedifferentiated, epithelioid, neuroendocrine, somatostatin, MDM2