Expanding the differential of cutaneous epithelioid tumors: A case of dedifferentiated liposarcoma with epithelioid features involving the skin, with review of the literature

Abstract

Liposarcomas are categorized into four distinct histopathological subtypes: atypical lipomatous tumors (ALT)/well-differentiated liposarcoma (WDL), dedifferentiated, myxoid, and pleomorphic. Dedifferentiated liposarcomas account for approximately 18% of all liposarcomas, characteristically arising in the deep soft tissue. They are reported to have lower rates of metastasis compared to other pleomorphic sarcomas. 1-3 The classic histopathologic appearance is ALT/WDL admixed or juxtaposed with a predominantly nonlipogenic sarcoma. Epithelioid features are rare, appearing in as few as 3% of tumors, and have not previously been reported in a superficial location. Herein, we present a 57-year-old male with intradermal and subcutaneous metastasis of his known deep dedifferentiated liposarcoma with epithelioid features.By H&E the tumor featured cords and sheets of crowded, plump, epithelioid cells with thick nuclear membranes and prominent nucleoli, which raised a broad differential including carcinoma and melanoma. By immunohistochemistry the tumor was diffusely positive for MDM2 and CDK4, on the other hand stains for Sox10, Melan A, MITF, CKAE1/3, desmin, and S100 protein were negative. This case serves as an opportunity to raise awareness of this rare morphological subtype, which can involve the skin and mimic epithelial and melanocytic malignancies. It can be a potential diagnostic pitfall, especially if metastases are the first presentation. K E Y W O R D S cutaneous, dedifferentiated, epithelioid, liposarcoma, MDM2, metastasis

Paratesticular Dedifferentiated Liposarcoma with Epithelioid Features: A Diagnostic Pitfall

“…Epithelioid features have been described in 13 cases of DDLPS with 2 of the 13 cases exhibiting paragangliomalike features (Table 1). 4,[10][11][12]25 In the current case, we favor the epithelioid component to be a morphologic variant of DDLPS rather than true epithelial or carcinomatous differentiation. Additional studies including ultrastructural analysis by election microscopy may help to determine whether these epithelioid areas truly show epithelial differentiation.…”

Superficial GLI1‐amplified mesenchymal neoplasms: Expanding the spectrum of an emerging entity which reaches the realm of dermatopathology

“…42,43 Finally, although the strong immunoreactivity for CDK4 raises the possibility of DDLPS, this neoplasm is rare in superficial locations and almost always harbors MDM2 amplification. 44 Prognosis, behavior, and histopathologic predictors are puzzling issues in tumors with GLI1 alterations and are still under debate. Various series of tumors with GLI1 alterations 4,[11][12][13][15][16][17]24,27 describe that many of the cases behave in a benign, indolent or low-grade fashion, but metastases and/or local recurrences have also been reported.…”

“…The morphologic differential diagnosis is broad; it includes vascular neoplasms 13,15–18,24,30–33 such as glomus tumor/myopericytoma, 30–33 skin adnexal carcinoma (hidradenocarcinoma, spiradenocarcinoma), 34,35 solitary fibrous tumor (SFT), 36 PEComa, 37,38 myoepithelial tumors, 39–41 extraskeletal myxoid chondrosarcoma (EMC), 42,43 and DDLPS 44 . Vascular neoplasms usually express one or more vascular markers (ERG, CD31, CD34) 13,15–18,24,30–33 and despite the D2‐40 immunoexpression in our cases, other vascular markers were all negative.…”

“…In addition, the solid variant of EMC may potentially resemble GLI1 ‐amplified tumors; in the appropriate morphologic setting the presence of NR4A3 rearrangements is diagnostic of this tumor 42,43 . Finally, although the strong immunoreactivity for CDK4 raises the possibility of DDLPS, this neoplasm is rare in superficial locations and almost always harbors MDM2 amplification 44 …”