Primary purely intradermal pleomorphic liposarcoma

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.

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

Liposarcoma, usually arises in deep soft tissues and pleomorphic liposarcoma (PL), is the rarest histopathologic variant. However, 15 cases of entirely dermal PL have been reported. We describe a case of a 79-year-old man who developed a rapidly growing nodule on his thorax. Excisional biopsy was performed and immunohistochemical studies were carried. The lesion was a well-circumscribed dermal nodule composed of multivacuolated pleomorphic lipoblasts and atypical mitotic figures. Neoplastic cells expressed CD10 and resulted negative S100 protein, Melan-A, MITF-1, AE1/AE3, CD4, CD68 (PGM1), retinoblastoma gene family protein, pericentrine and lysozyme. Adipophilin stain showed the lipid contents in the cytoplasm of the neoplastic cells. MDM2 and CDK4 resulted both negative. A diagnosis of primary dermal PL was made. This case shows the utility of adipophilin immunostaining to prove the lipid contents in neoplastic cells, which has the advantage of using formalin-fixed paraffin-embedded tissue and making needless frozen sections and ultrastructural studies to show these findings. Negative MDM2/CDK4 staining in our case argues against the possibility of dedifferentiated liposarcoma and further supports the diagnosis of true PL.

Cutaneous metastasis of pleomorphic liposarcoma to the scalp: an elusive diagnosis

Liposarcomas are one of the most common sarcomas arising in the extremities of the elderly. Various subtypes of liposarcomas include well-differentiated liposarcomas, dedifferentiated liposarcomas, myxoid liposarcomas and pleomorphic liposarcomas. Pleomorphic liposarcomas are the rarest subtype and have the highest malignant potential compared with the other subtypes of liposarcomas. Metastases to internal organs are common but cutaneous metastasis is very rare with only few cases in the literature. We present a patient with a known diagnosis of stage IV metastatic liposarcoma who presented to our clinic with a rapidly growing nodule on the scalp. A biopsy showed a high-grade poorly differentiated spindled cell neoplasm sparing the epidermis with scattered lipoblasts. Immunostaining for S100, SOX10, and MNF-116 were negative. To further characterize the neoplasm, immunostaining with MDM-2 was performed and was also found to be negative. The histologic appearance, immunohistochemical staining, and clinical history support a diagnosis of metastatic pleomorphic liposarcoma to the scalp. The diagnosis of pleomorphic liposarcoma is challenging. It is often difficult to differentiate from myxofibrosarcoma or other high-grade pleomorphic sarcomas based on histology alone. However, the presence of bizarre lipoblasts and negative MDM-2 staining can be helpful clues to differentiate this neoplasm from histologic mimics.

Pleomorphic liposarcoma: a clinicopathological, immunohistochemical and molecular cytogenetic study of 32 additional cases

The purpose of this study is to report the author's experience with 32 cases of pleomorphic liposarcoma to further broaden the clinicopathological spectrum. The tumours occurred equally in males and females with ages ranging from 11 to 83 years (median, 56 years). Tumour site included the extremities (17 cases), abdomen/retroperitoneum (4 cases), internal organs (5 cases), thoracic cavity/mediastinum (2 cases), orbit, neck, groin and scrotum (1 case each). The diagnostic pleomorphic lipoblasts were identified in 31 primary tumours and one recurrent tumor but varied widely in proportion between cases or different areas of the same tumor. Four tumors contained sheets or focal aggregates of lipoblasts with epithelioid morphology. The nonlipogenic component in 26 cases had an appearance of undifferentiated pleomorphic sarcoma, whereas in six cases it was consistent with intermediate to high grade myxofibrosarcoma. The pleormorphic and epithelioid lipoblasts displayed variable expression of S100 protein. There was no signal of amplified MDM2 gene in 10 cases tested by fluorescence in situ hybridization. This study further illustrates that pleomorphic liposarcoma is a distinctive entity with no relationship to either well differentiated liposarcoma or dedifferentiated liposarcoma. Albeit very rare, pleomorphic liposarcoma can occur in teenaged patients and internal organs.

Atypical lipomatous tumor/"well-differentiated liposarcoma" of the skin clinically presenting as a skin tag: clinicopathologic, immunohistochemical, and molecular analysis of 2 cases

Liposarcomas are extremely rare in the skin. When they involve the skin, it is usually by upward spread from a subcutaneous or deeper seated liposarcoma. Very rarely, liposarcoma metastasize to the skin or arise as a primary dermal lesion. We describe 2 cases of atypical lipomatous tumor "well-differentiated liposarcoma" located in dermis. Both presented clinically as a skin tag. The neoplasms arose in a 56-year-old female and a 69-year-old male patient. Both lesions were treated by excision and reexcision. In addition to classical morphology of atypical lipomatous tumor with evidence of lipoblasts and atypical adipocytes, immunohistochemistry with nuclear murine double-minute type 2 protein and cyclin-dependent kinase-4 expression as well as fluorescence in situ hybridization analysis showing an amplification of murine double-minute type 2 protein and cyclin-dependent kinase-4 were helpful to establish the diagnosis. None of the cases recurred after surgical treatment. These 2 cases show the importance of not to misdiagnose lesions which clinically may appear to be benign.

Aspects of the differential diagnosis of clear-cell lesions of the skin in connection with the rare case of a clear-cell atypical fibroxanthoma

Clear-cell changes are rare in histological specimens of the dermis and raise complex diagnostic considerations regarding lineage differentiation (e.g., epithelial, mesenchymal, or melanocytic). We present a clear-cell atypical fibroxanthoma (CCAFX) and describe the morphological and immunohistochemical aspects of this rare skin lesion. Furthermore, we give an overview of the differential diagnoses of clear-cell lesions of the skin for a practical approach.

Clear cell atypical fibroxanthoma - report of a case with review of the literature

Clear cell atypical fibroxanthoma (CCAFX) is a rare variant of atypical fibroxanthoma (AFX), a pleomorphic dermal tumour associated with a good prognosis. A 67-year-old man presented with a rapidly growing nodule on the ear, which had appeared over a 2-week period. Sections showed an ulcerated nodule composed of pleomorphic spindled and polygonal cells with clear cytoplasm, invested by a delicate vascular stroma, reminiscent of clear cell renal cell carcinoma. Numerous mitotic figures were seen. The tumour cells stained with vimentin, CD68 and CD99 and were cytokeratin-negative. The immunohistochemical and ultrastructural features supported a diagnosis of CCAFX. The diagnosis of CCAFX requires the exclusion of other pleomorphic clear cell tumours that can occur in the skin by using a combination of morphology, immunohistochemistry and electronmicroscopy. Murali R, Palfreeman S. Clear cell atypical fibroxanthoma - report of a case with review of the literature.

Calretinin expression in tumors of adipose tissue

Although well established as a marker of mesothelial cells, calretinin is also expressed in several other tissue types, including adipose tissue. Accordingly, immunohistochemical staining for calretinin has been described in an increasing number of neoplasms other than mesothelioma. A detailed analysis of calretinin expression in lipogenic tumors has not yet been reported, however. Given the known expression patterns of calretinin in normal tissues, we predicted that calretinin immunoreactivity would be detected in lipoma and the various histologic subtypes of liposarcoma, and that this marker might be of use in the differential diagnosis of selected fatty tumors. A variety of pleomorphic and small round cell sarcomas were studied for comparison. Calretinin immunoreactivity was detected, at least focally, in all 10 samples of normal adipose tissue and in 22 of 23 lipomas or lipoma variants. Staining for calretinin was also positive within the lipogenic component of 28 of 29 liposarcoma variants. Of the 7 dedifferentiated liposarcomas, 3 were focally positive for calretinin. Pleomorphic variants of other sarcomas, including undifferentiated high-grade pleomorphic sarcoma, rhabdomyosarcoma, leiomyosarcoma, and malignant peripheral nerve sheath tumor also exhibited focal calretinin immunoreactivity in a minority of cases, as did some small round cell sarcomas. These results suggest that calretinin immunoreactivity in normal and neoplastic adipose tissue is more ubiquitous than previously reported and may be a useful, albeit nonspecific marker of lipogenic differentiation. However, its utility in the differential diagnosis of fatty tumors appears limited.