Abstract:

A 30-year-old woman presented with a 5-year history of recurrent nodular lesions in the left subaxillary region, which had rapidly grown for 7 weeks. Five years prior to the presentation, she received breast conservation surgery and radiotherapy for left breast cancer, thereafter, chronic radiation dermatitis developed in the left subaxillary region. Two years after the operation, three soybean-sized bright red nodules appeared in the lesions of radiation dermatitis, and slowly enlarged. Subsequently, the nodules were resected, but a local recurrence was observed 3 weeks after the resection. The recurrent masses underwent accelerated growth during her pregnancy, and the growth was obviously inhibited after the termination of pregnancy. Physical examination revealed a quasi-elliptic, dark or bright red plaque measuring about 18 cm × 14 cm with a smooth surface in left subaxillary region, and in the center of the plaque was a bright red, hemispheric, elevated lesion measuring 10 cm × 9 cm × 5 cm with erosions or pitchy crusts on the surface. Histopathology of the lesions showed that the tumor was located in the dermis and consisted of densely packed uniform spindle-shaped cells arranged in a characteristic storiform or whirlpool pattern. Some cell nuclei showed atypia, and few mitoses were observed. In some parts of the lesion, tumor cells were arranged in a herringbone pattern. Immunohistochemistry revealed that the tumor cells stained positive for vimentin （strongly） and actin （weakly）, but negative for CD34. Based on these findings, a diagnosis of postradiation dermatofibrosarcoma protuberans （fibrosarcoma type） was made.

Key words: Negative for CD34