Giant Desmoid Fibromatosis of the Small Bowel After Sleeve Gastrectomy: Case Report and Review of the Literature.

Introduction: Desmoid fibromatosis (DF) is a rare, locally invasive, and typically non-metastatic neoplasm. Its pathophysiology is poorly understood, and the subtle clinical presentation makes diagnosis challenging. A multidisciplinary approach is necessary to achieve a definitive diagnosis and identify the most effective therapeutic strategy. Because of its heterogeneous presentation and unpredictable behavior, DF cannot be managed through a standardized protocol, and diagnostic and therapeutic decisions must instead be tailored to the individual patient, consistent with a personalized-medicine approach. We present an unusual case in which we aim to evaluate the diagnostic procedures and treatments used and determine whether they align with the recent literature. Materials and Methods: A case report. A 27-year-old man presented with fever and worsening abdominal pain, without clinical signs of intestinal obstruction. He had undergone a sleeve gastrectomy five years earlier. A computed tomography (CT) scan revealed an intra-abdominal mass in the mesohypogastric region, likely originating from the mesentery of the small intestine. The patient underwent a right hemicolectomy extended to the terminal ileum. Histopathological examination and immunohistochemistry confirmed the diagnosis of DF. The patient was discharged on the 5th postoperative day (POD) in good general clinical condition. To date, there are no signs of recurrence. Conclusions: The multidisciplinary approach is essential for managing DF and R0 surgical resection remains the gold standard. The diagnostic and therapeutic pathway followed in our patient appears consistent with the recent literature. This case illustrates how individualized clinical reasoning can be applied even to a rare, heterogeneous neoplasm for which no standardized protocol exists. Furthermore, an established post-surgical management protocol for DF has not yet been developed. Additionally, we observed a possible, hypothesis-generating association between bariatric surgery and the subsequent onset of an intra-abdominal desmoid tumor; given the rarity of desmoid fibromatosis relative to the high volume of bariatric procedures performed worldwide, this observation should not be interpreted as a confirmed correlation, and we conducted a literature review to explore it as a hypothesis. Numerous studies are needed on this matter, but we hope that this case can provide a small starting point for subsequent studies.