Primary dermal pleomorphic liposarcoma: utility of adipophilin and MDM2/CDK4 immunostainings

Primary Cutaneous Atypical Spindle Cell Lipomatous Tumor

This report documents an exophytic, pedunculated nodule in a 74-year-old man that upon histopathological examination revealed an atypical spindle cell/pleomorphic lipomatous tumor (ASPLT) confined to the papillary and reticular dermis, representing the fourth documented case within the skin. Despite the overt pleomorphic changes present histologically, the patient is free of metastasis or recurrence five years after surgery.

Clear Cell Proliferations of the Skin: A Histopathologic Review

ABSTRACT

Cutaneous clear cell proliferations encompass a heterogenous group of several primary cutaneous neoplasms and metastatic tumors with different histogenesis. Many of these clear cell proliferations may seem strikingly similar under the microscope resulting in challenging diagnosis. In many of these clear cell lesions, the reason for the clear or pale appearance of proliferating cells is unknown, whereas in other ones, this clear cell appearance is due to intracytoplasmic accumulation of glycogen, mucin, or lipid. Artifacts of tissue processing and degenerative phenomenon may also be responsible for the clear cell appearance of proliferating cells. Awareness of the histopathologic findings as well as histochemical and immunohistochemical techniques are crucial to the accurate diagnosis. This review details the histopathologic features of clear cell cutaneous proliferations, classifying them according their type of differentiation and paying special attention to the histopathologic differential diagnosis among them.

The Rapidly Expanding Group of RB1-Deleted Soft Tissue Tumors: An Updated Review

The classification of soft tissue tumors has evolved considerably in the last decade, largely due to advances in understanding the pathogenetic basis of many of these, sometimes rare, tumors. Deletion of Retinoblastoma 1 (RB1), a well-known tumor suppressor gene, has been implicated in the tumorigenesis of a particular group of soft tissue neoplasms. This group of so-called “RB1-deleted soft tissue tumors” has been rapidly expanding in recent years, currently consisting of spindle cell/pleomorphic lipoma, atypical spindle cell/pleomorphic lipomatous tumor, pleomorphic liposarcoma, myofibroblastoma, cellular angiofibroma, and acral fibromyxoma. Most of these neoplasms, except pleomorphic liposarcoma, are considered benign entities and are mainly described in the older adult population. This article will review the currently known morphological, immunohistochemical, and molecular features of this heterogeneous group of mesenchymal tumors with an emphasis on differential diagnosis.

A Reappraisal of Superficial Pleomorphic Liposarcoma

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.

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

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.

Liposarcoma: Advances in Cellular and Molecular Genetics Alterations and Corresponding Clinical Treatment

Liposarcoma is a malignant tumor of mesenchymal origin with significant tissue diversity. It is composed of adipocytes with different degrees of differentiation and different degrees of heteromorphosis. It is not sensitive to traditional radiotherapy and chemotherapy and has a poor prognosis. In recent years, with the rapid development of basic immunology, molecular genetics and tumor molecular biology, the histological classification of liposarcoma has become increasingly clear. More and more new methods and technologies, such as gene expression profile analysis, the whole genome sequencing, miRNA expression profile analysis and RNA sequencing, have been successfully applied to liposarcoma, bringing about a deeper understanding of gene expression changes and molecular pathogenic mechanisms in the occurrence and development of liposarcoma. This study reviews the present research status and progress of cellular and molecular alterations of liposarcoma and corresponding clinical treatment progress.

Pleomorphic Sarcomas: The State of the Art

This article focuses on pleomorphic sarcomas, which are malignant mesenchymal tumors with complex genetic background at the root of their morphologic pleomorphism. They are poorly differentiated tumors that may retain different lines of differentiation, sometimes correlating with clinicopathological or prognostic features. Accurate diagnosis in this group of tumors relies on adequate sampling due to their heterogeneity and assessment with both microscopy and large panels of immunohistochemistry. Molecular analyses have a limited role in their diagnosis as opposed to translocation-related sarcomas but may provide theranostic and important prognostic information in the future.