Fibrosarcomatous variant of dermatofibrosarcoma protuberans with pancreatic metastasis

Dermatofibrosarcoma protuberans (DFSP) is an intermediate malignant tumor with the nature of locally aggressive features but has low potential for distant metastasis (1–6%).1 Most metastasis occurs after multiple local recurrences, which shows the importance of wide local excision. The lung is the major metastatic organ of this disease, whereas pancreatic metastasis has been reported in only three cases.2-4 The fibrosarcomatous variant of DFSP seems to be an aggressive variant and has higher metastatic ability than ordinary DFSP.5 Here, we report a case of the fibrosarcomatous variant of DFSP with pancreatic metastasis. A 50-year-old man consulted our hospital with a 30-year history of an ulcerated tumor on his left abdomen. He had a sessile, ulcerated and elastic hard tumor measuring 14 × 11 × 7 cm (Fig. 1a). The tumor was excised with a 3-cm margin and with fasciae. Histopathologically, the tumor consisted of two parts (Fig. 1b). In the superficial region, spindle-shaped cells were arranged in a storiform pattern (Fig. 1c) and were strongly positive for CD34 (Fig. 1e). In the deep region, spindle-shaped cells with high density showed a herringbone pattern (Fig. 1d) and were weakly positive for CD34 (Fig. 1f). We diagnosed this tumor as a fibrosarcomatous variant of DFSP. Surgical margins were free for at least 8 mm, and no fascial invasions were detected. The MIB-1 index was increased up to 25% in the deep region (Fig. 1g). Six months after the initial surgery, a mass was detected in his pancreas by computed tomography (Fig. 2a). We resected the tumor, 26 mm in diameter, in the pancreatic tail by laparoscopic surgery (Fig. 2b). Histopathologically, the pancreatic tumor showed a her-ringbone pattern with weak CD34 staining, similar to the deep region of the skin tumor (Fig. 2c). We made a diagnosis of pancreatic metastasis of DFSP. Surgical margins were free, and lymph node invasion was not observed around the pancreas. Six months later, there was no sign of recurrence. Previously, there have been three reports of pancreatic metastasis of DFSP,2-4 including an autopsy case.2 Two non-autopsy cases were the fibrosarcomatous variant, and their metastases occurred eight months and three years later, respectively. In our case, metastasis occurred six months after local resection. Rapid metastasis suggests an aggressive feature of the fibrosarcomatous variant. Compared with ordinary DFSP, cases of pancreatic metastasis showed large primary tumors, 6, 12, and 14 cm. Further, ulceration was associated in two cases. These clinical findings suggest that the fibrosarcomatous variant of DFSP is likely to have more aggressive features. In addition, while all the parts of the tumor showed positive to CD34 in this case, the fibrosarcomatous region and metastasis showed lower staining intensity. In association with CD34 staining, MIB-1 index, marker for proliferation, was quite high in the fibrosarcomatous part of the primary tumor. MIB-1 index is considered a useful marker of the malignancy grade.6 More than 20% positivity seems to be an independent marker of high-grade sarcomas.7 These immunohistochemical findings suggest the different and more aggressive nature of this variant than common DFSP. Close attention to the development of metastasis is required in cases of the fibrosarcomatous variant of DFSP.