Metachronous Dermatofibrosarcoma Protuberans (DFSP) and Gastrointestinal Stromal Tumour (GIST): Case Series with Review of Literature

Introduction: The occurrence of metachronous Dermatofibrosarcoma protuberans (DFSP) and Gastrointestinal stromal tumour (GIST) in the same individual is very rare, with few cases reported in the literature. Individually, (DFSP) and (GIST) are slow-growing tumours which are notorious for recurrence, especially if incompletely excised. They are both related to a mutation in the function of platelet-derived growth factor Receptor (PDGFR). We present two cases of metachronous DFSP and GIST, and review the literature. A 60-year-old male presented with a recurrent anterior abdominal wall mass of 2 years’ duration. He had 4 excisions, in 6 years. Histopathologically, the last lesions was diagnosed as DFSP. Five (5) years later, the patient presented with an abdominal mass that was excised and histopathologically reported as Extra Gastrointestinal Stromal Tumour (eGIST). The second patient was a 35-year-old male who had had recurrent excision of a mass at the lower right back, which was histopathologically diagnosed as DFSP. The area was treated with radiotherapy after the surgery. Five (5) years later, he presented with haematemesis and weight loss. A CT scan of the abdomen revealed a large mass closely associated with the stomach. Though initially deemed unresectable, it was later resected because of poor response to targeted therapy with imatinib, with the patient continuing to have persistent severe anaemia and fever. Confirmatory immunohistochemistry (CD117 and DOG-1) was performed in both cases to confirm the diagnosis. Patient number 2, the 35-year-old, only received adjuvant targeted therapy without response. Informed written consent was obtained from the patients, and medical records were obtained from the electronic medical records of the Korle Bu Teaching Hospital. One patient died within 21 days of follow-up, while the other is living without disease 7 months after surgery. CONCLUSION: These two cases highlight the possibility of metachronous occurrence of DFSP and GIST and underscore the need for attending clinicians to maintain a high index of suspicion for this occurrence in patients managed for DFSP.