Dermatologica Sinica

: 2020  |  Volume : 38  |  Issue : 4  |  Page : 242--243

Cutaneous clear cell sarcoma mimicking xanthogranuloma: A diagnostic pitfall

Chung-Hao Hsu1, Chi-Shun Yang2, Chung-Yang Yen1,  
1 Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan
2 Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital; Department of Nursing, Hungkuang University, Taichung, Taiwan

Correspondence Address:
Dr. Chi-Shun Yang
Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital, No. 1650, Section 4, Taiwan Boulevard, Taichung 40705

How to cite this article:
Hsu CH, Yang CS, Yen CY. Cutaneous clear cell sarcoma mimicking xanthogranuloma: A diagnostic pitfall.Dermatol Sin 2020;38:242-243

How to cite this URL:
Hsu CH, Yang CS, Yen CY. Cutaneous clear cell sarcoma mimicking xanthogranuloma: A diagnostic pitfall. Dermatol Sin [serial online] 2020 [cited 2021 Aug 3 ];38:242-243
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Full Text

Dear Editor,

Clear cell sarcoma (CCS), also known as melanoma of soft parts, often manifests as a deep soft-tissue mass at the tendon and aponeurosis of the distal extremity of young adults. Primary cutaneous CCS is extremely rare.[1],[2],[3],[4] Herein, we reported a unique case of nonpigmented dermal CCS, resembling xanthogranuloma, with the presentation of a small nodule on the finger.

A 26-year-old woman presented with a 1 cm × 1 cm, well-defined, asymptomatic skin-colored nodule that had existed for a year at the left fourth finger [Figure 1]a. Excisional biopsy was performed. Pathologically, there was an ill-defined dermal tumor with nested and fascicular growth pattern, separated by collagenous bands. The tumor cells were composed of epithelioid to spindled nuclei and pale eosinophilic cytoplasm with a mixture of prominent wreath-like multinucleated giant cells [Figure 1]b, [Figure 1]c, [Figure 1]d. Perineural involvement was observed, but no necrosis was found. The mitotic activity of the tumor cells was difficult to find (<1/50 high-power field). Immunohistochemical stains of tumor cells and multinucleated giant cells were both positive for SOX-10, S-100, and MITF while negative for cytokeratin, HMB45, CD68, CD163, factor XIIIa, CD1a, and Langerin [Figure 2]a, [Figure 2]b, [Figure 2]c. Fluorescence in situ hybridization assay for EWSR1 gene rearrangement showed positive results with split signals [Figure 2]d. Further examination of positron emission tomography and bone scan revealed neither local bony involvement nor distant metastasis. Based on the morphology, immunohistochemical staining, cytogenetic study, and image survey, cutaneous CCS was diagnosed. The patient then received wide local excision for the residual tumor. She stayed alive without local recurrence and metastasis three months after the surgery.{Figure 1}{Figure 2}

In the present case, the differential diagnoses included xanthogranuloma, cellular neurothekeoma, Spitz nevus, and melanoma. The presence of Touton type-like multinucleated giant cells, epithelioid cells, and the dermal-based location is reminiscent of xanthogranuloma, which is a potential diagnostic pitfall. However, the Touton-type giant cell in xanthogranuloma shows xanthomatized foamy cytoplasm peripherally, which is different from that of CCS. Cellular neurothekeoma shares similar histologic features with CCS by the presence of nested and fascicular arrangement of tumor cells, while it usually lacks the prominent multinucleated giant cells.[5] The distinction of CCS from the abovementioned two kinds of tumors can be made with the aid of immunohistochemical stainings. CCS shows both immunohistochemical and ultrastructural evidence of melanocytic differentiation. There are significant histologic and immunohistochemical overlapping features across the CCS and melanocytic tumors.[6] For example, epidermal involvement in cutaneous CCS with nests of tumor cells populated at the dermoepidermal junction, although rare, makes a difficult differentiation of CCS from other melanocytic tumors.[2],[3] Nonetheless, there are still some morphologic features unique to cutaneous CCS. First, nests and fascicles of tumor cells in CCS are often surrounded by delicate fibrous septa or hyalinized stroma. Second, subtle cellular atypia and nuclear pleomorphism present in CCS are uncommon in melanoma. Third, the presence of wreath-like multinucleated giant cells with peripherally located monomorphic nuclei, as observed in two-third of CCS cases, is another helpful diagnostic clue.[1],[2] Cytogenetic study revealed that most CCS cases (>90%) are characterized by the t(12;22) translocation resulting in the production of EWSR1/ATF1 fusion gene, and a minority of cases harbor EWSR1/CREB1 fusion gene resulting from t(2;22) translocation. These molecular changes are not detected in the melanoma and Spitz nevus. Such finding is helpful in distinguishing CCS from other melanocytic tumors.[1],[2],[6]

CCS of soft tissue usually follows a dismal clinical course with frequent local recurrence and late distant metastasis. The survival rates are 67% for 5 years, 33% for 10 years, and 10% for 20 years. Poor prognostic factors include large tumor size (>5 cm), tumor necrosis, and local recurrence.[6] On the other hand, cutaneous CCS were reported to have a better prognosis than soft tissue counterparts with smaller tumor sizes (mean: 1.1 ± 0.6 cm), less tumor necrosis, as well as less frequent local recurrence and distant metastasis.[4] The optimal CCS treatment strategy is wide local excision with an adequate safety margin. Radical amputation is not indicated because its survival rate is not different from surgical resections. Chemotherapy and radiotherapy have minimal effects on CCS treatment.[4],[7]

In conclusion, cutaneous CCS is a rare tumor that could be easily misdiagnosed as other melanocytic tumors or xanthogranuloma. Awareness of the unique histologic features, including nested and fascicular arrangement of tumor cells and wreath-like multinucleated giant cells, as well as the application of cytogenetic study, would be helpful in the early diagnosis of this malignant disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal the identity, but anonymity cannot be guaranteed.

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