Dermatofibrosarcoma Protuberans With a Small Focus of Fibrosarcomatous Transformation: An Easily Overlooked, Clinically Significant Entity

Background: Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous soft tissue tumour of intermediate malignant potential and tends to recur. Fibrosarcomatous transformation in DFSP is an uncommon event associated with more aggressive behaviour, including increased risk for recurrence and metastasis. Case Presentation: We report a case of DFSP with fibrosarcomatous transformation in a 44-year-old male who presented with a rapidly enlarging superficial mass over the anterior abdominal wall, following a prolonged history of slow growth. The lesion was initially small and had gradually increased in size over the past 15 years, with rapid enlargement in the past two months. After fine needle aspiration cytology (FNAC), an initial diagnosis of low-grade spindle cell neoplasm was given. Ultrasonographic imaging revealed a predominantly superficial mass with homogenous echogenicity. The patient was treated surgically with a wide local excision. Histopathologic examination thereafter revealed a small focus of fibrosarcomatous transformation in DFSP with free resected margins. After 2 years of follow-up, the patient is well and has no evidence of recurrence or metastasis.Conclusion: This case report highlights the importance of identifying even small focal fibrosarcomatous transformations in DFSP, necessitating thorough sampling and close clinical surveillance