Abstract
BACKGROUND: Epithelioid sarcoma is a rare, high-grade malignant tumor of the soft tissue. The incidence of local recurrence, regional lymph node involvement, and distant metastases is high. Epithelioid sarcoma is most often seen in adolescents and young adults. In the early stage before the development of full clinical features, epithelioid sarcoma is often misdiagnosed as a benign disease such as granuloma. CASE PRESENTATION: We report a case of a 74-year-old Japanese woman whose epithelioid sarcoma was initially misdiagnosed as fungal infection. Rebiopsy revealed the proliferation of atypical polygonal or oval epithelioid cells in the dermis and lymphocyte infiltration through the dermis. Immunohistochemically, the tumor cells were positive for vimentin, cell adhesion molecule 5.2, epithelial membrane antigen, and E26-related gene. The nuclear expression of integrase interactor 1 was lost in the tumor cells. CONCLUSIONS: We encountered a rare case of epithelioid sarcoma and had difficulty in making the correct diagnosis. We suggest that in patients whose lesions are resistant to conventional treatments, repeat biopsy and immunohistochemical studies should be considered to rule out rare epithelioid sarcoma.