1. Clinical data Case 1: The patient, female, 41 years old, was admitted to the hospital because of the right breast mass repeated excision for 3 times, and the recurrence of the mass for 2 months with progressive growth and ulceration for a few days. 1993, the patient was admitted to the hospital because of the striated mass above the right breast, with red knots on the surface, and was treated with lumpectomy in the outside hospital; in 2004, a mass grew out of the incision of the right breast, about the size of an egg, and the surface was still accompanied by red knots, and was treated with lumpectomy in the outside hospital; and in 2006, a lump grew again at the original incision, with progressive growth, accompanied by skin ulceration and bleeding, and was treated with lumpectomy again. In 2006, a lump appeared at the original incision, which grew progressively, accompanied by skin ulceration and bleeding, and was again subjected to lumpectomy in an outside hospital, and no examination was performed after the three operations. Specialized situation: right breast swelling, the upper part spread to the clavicle, a dark red neoplasm of about 10×6cm was seen above the right breast, protruding from the skin, with local hemorrhage and necrosis. Ultrasound: 6.3×9.0cm mass shadow was seen below the right breast, with reduced echogenicity, point-like isoechoic echo, which appeared to be liquid, CDFI: rich blood flow signal was seen, and arterial and venous spectra could be detected by PW; a larger mass shadow, with anteroposterior and anterior diameters of 7.0cm was seen above the right breast, with the same echo as before, and rich blood flow was seen in the mass.CT: a mass was seen in the right breast region, with the size of about 13×9.5cm, and density was not uniform, and scattered small patches were seen. CT showed that a mass of about 13×9.5cm in size was seen in the right breast region, and the density in the mass was not homogeneous, with scattered small patchy high-density shadows, and the deep surface of the chest muscle was not clear. Simple mastectomy plus pectoralis major myotomy + axillary lymph node dissection was performed on the right breast. Postoperative examination showed: bulging dermatofibrosarcoma, no tumor involvement in the right axillary lymph node (0/15), immunohistochemistry: CD34 (++); Bcl-2 (+/-); CD68 (-); α-ACT (+); Actin (-); S-100 (-). Radiotherapy was not performed after surgery for economic reasons, and a localized recurrence on the right chest wall appeared at 3 months of postoperative follow-up, which was not treated again. Case 2: The patient, female, 15 years old, was admitted to the hospital because of the discovery of a painless mass in the left breast for more than 4 months. Specialized conditions: a mass of about 12×8 cm in size was found above the left breast, which was hard, smooth, movable, and had clear borders. Color ultrasound: the left breast can be seen about 4.2×12cm size hypoechoic mass shadow, the border is still clear, see the peripheral echoes, the morphology is irregular, seems to be fused by a number of fusion, CDFI: the mass shadow is seen within the rich blood flow signals, PW detected arterial and venous spectra. Extended excision of the left breast lesion was performed, postoperative examination showed: bulging dermatofibrosarcoma, immunohistochemistry; CD34 (++); S-100 (-); Actin (-); Vimentin (++); Bcl-2 (+); Ki-67 positive cells number of about 10%. After surgery, 50 Gy of local radiotherapy was completed, and no recurrence was observed at 34 months of postoperative follow-up. 2, Discussion Dermatofibrosarcoma protuberans (DFSP) is also known as progressive recurring dermatofibrosarcoma (progressive recurring dermatofibroma) and sarcomatoid fibroma of skin. skin). It is more common in males than in females. It can occur at any age. It is more common in middle age. It can also occur in children. It can occur in all parts of the body, but is more common in the trunk and proximal extremities, and in the anterior chest. Inadequate resection may result in recurrence, and metastasis to the lungs or nearby lymph nodes occasionally occurs in advanced stages [1]. Clinical manifestations include a single reddish or bluish-purple elevated mass, or multiple nodules on it, with a firm, slightly shiny surface, adherent to the epidermis or subcutaneous tissue. In the advanced stage, the surface skin may be atrophic and thin. Capillary dilatation and even ulceration can be seen: the typical pathology is characterized by spindle-shaped cells arranged radially like a wheel. Microscopically, it can be seen to spread to the fat layer and invade the fat layer like honeycomb features. Nuclear division is relatively rare. DFSP clinical misdiagnosis rate is high, combined with the literature analysis of the reasons for misdiagnosis of DFSP, there are the following points: ① the first treatment is not standardized, did not carry out pathological examination; ② DFSP clinical rarity, clinicians lack of sufficient knowledge of it, for the repeated recurrence of the patient did not pay enough attention; ③ the tumor is located in the body surface, the doctor and the patient are satisfied with surgical excision, the doctor and the patient are satisfied with surgical excision, and the patient is not satisfied with surgical excision, the doctor is satisfied with surgical resection. The tumor is located on the surface of the body, so doctors and patients are satisfied with surgical resection, and no further examination is done to confirm the diagnosis; ④ This disease is easy to be confused with dermatofibroma, sebaceous cysts, keloid scars and other benign lesions in clinic. Therefore, once a painless hard nodule located on the proximal end of the trunk and limbs, elevated on the surface of the skin and reddish in color, the possibility of DFSP should be considered, and those who have recurrence in the original excision in a short period of time should be more alert to the disease; and immunohistochemical indexes such as CD34 can be tested to assist in the diagnosis of Dermal fibrosarcoma of breast elevation: ① Surgical excision: Surgical treatment adopts a large-scale excision. or using Mohs micrographic surgery (MMS). The incision margin must exceed the tumor (independent of the tumor size) edge more than 3M of normal skin, deeper than 1-2cm of normal deep tissue in the subcutaneous or fascial layer; and it is recommended to send frozen section to clarify the diagnosis and to know whether the surgical margin is positive or not, and if the margin is positive, then the scope of surgery needs to be enlarged again [4, 5]. After extensive resection of breast augmentation dermatofibrosarcoma causing a large defect in the breast can be considered at the same time to perform the latissimus dorsi myocutaneous flap transfer and other autologous tissue transplantation in order to maintain the shape of the breast, because of breast augmentation dermatofibrosarcoma metastasis is very small, generally not the axillary lymph node clearance; ② postoperative local radiotherapy: the traditional concept that the DFSP is insensitive to chemotherapy and radiotherapy. However, recent studies have confirmed that post-surgical radiotherapy can reduce the recurrence of DFSP. Dagan [6] and others reported that post-surgical radiotherapy can reduce the risk of local recurrence of DFSP after surgery, and there is no serious radiotherapy complications. Chen Fan [7] reported that postoperative radiotherapy can effectively reduce the recurrence rate of DFSP, and the radiotherapy dose of 50-60Gy is more appropriate. For large lumps of breast bulging dermatofibrosarcoma, wide excision will cause a large defect in the shape of the breast, so the excision range may sometimes appear to be insufficient, and then postoperative local radiotherapy is particularly important. In the treatment of bulging dermatofibrosarcoma, wide excision inevitably results in a large loss of breast shape. For female patients, it will cause a large psychological burden and a series of family problems; especially for patients with recurrent recurrence after resection and young patients, these problems are particularly prominent. Therefore, early detection, early diagnosis and standardized treatment of breast bulging dermatofibrosarcoma is particularly important; when the mass is small, the breast shape defect after wide excision is small, and at the same time, supplemented with postoperative radiotherapy, in order to achieve the goal of radical treatment.