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Introduction Dermatofibrosarcoma protuberans (DFSP) is a rare soft-tissue neoplasm that was first identified by Taylor, RW in 1890. It was then described in 1924 by Darier, J and Ferrand, M as a progressive recurrent dermatofibroma, and was later termed DFSP by Hoffmann in 1925. The most common sites for development of DFSP are the trunk (42–72%) and extremities (16–30%). However, Prabhu et al. reported rare sites for development including the hand, gluteal region, head and neck region, toe, vulva, and parotid gland. However, this patient\'s type of localization in the cheek is very rare.
Case report The patient underwent a wide local excision under local anesthesia without complications. The tumor measured approximately 2.5 × 2.0 × 2.0 cm (Fig. 1). The final histopathological analysis revealed a cellular tumor with increased cellularity and large, spindle-shaped nuclei arranged in irregular, intertwining bands in a storiform pattern. Mild atypicality was also observed. A cartwheel appearance (storiform pattern) of spindle-shaped nuclei determined through microscopy is characteristic of DFSP (Fig. 2). Immunohistochemistry showed strong positivity for CD34 (Fig. 3), and negativity for S-100 and CD68 (Fig. 4a and b). The mass was eventually diagnosed as DFSP of the cheek.
Discussion DFSP is a rare soft-tissue tumor with intermediate-grade malignancy arising from the AP20187 which was first recognized by Talar, RW in 1890 and described by Darier, J and Ferrand, M in 1924 as an unusual progressive and recurring tumor of skin of fibromatous or fibrosarcomatous character. DFSP represents approximately 1% of soft-tissue sarcomas with an estimated incidence of 0.8–5.0 cases per million per year in the United States of America. It has little propensity for distant metastasis but a strong tendency for extensive infiltration and frequent local recurrence after excision. Most patients are between 20 and 50 years of age, but the tumor can be found in patients of all ages. Because of the similar clinical appearance of DFSP to other lesions, tissue evaluation is imperative for proper diagnosis. Previously, fine-needle aspiration has been reported to facilitate the establishment of a differential diagnosis of spindle squamous cell carcinoma, spindle cell melanoma, and leiomyosarcoma. However, tissues procedure is less useful for facilitating the diagnosis of DFSP, and should serve only as a prompt for a more extensive tissue diagnosis. Histologic immunohistochemical staining for CD34 serves as a highly specific technique for diagnosing DFSP. This process is not specific for DFSP, but is highly sensitive and therefore beneficial. In our case, the immunohistochemistry showed strong positivity for CD34 and negativity for S-100 and CD68. Immunohistochemical staining demonstrated possible positivity for CD68 for benign fibrous histiocytoma, and positivity for S-100 for leiomyosarcoma, neurogenic tumors, and melanoma. The recommended form of treatment for DFSP is wide local excision of the tumor after including the subjacent fascia and a margin of apparently normal tissue in all planes. A local recurrence rate of 20–50% has been reported in cases with incomplete resection. Patients with unresectable or positive margins should be treated with adjuvant radiotherapy to reduce the recurrence rate. Paradici et al. reported a significantly lower recurrence rate in patients subjected to modified Mohs micrographic surgery (MMS) compared with those patients treated with wide local excision. However, evidence is inconclusive for any advantage of MMS in nonprimary cases, whereas MMS was the most effective in treating head and neck tumors.
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