EP381 - Prolapse of Giant Rectal Polyp with Necrosis: Unusual Presentation of Spindle Cell Malignant Neoplasm of the Rectum

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Purpose/Background: Spindle cell malignant neoplasms of the rectum are a rare variant of malignant tumors characterized by the proliferation of spindle-shaped cells. These tumors can cause diagnostic confusion due to their similarity to other benign rectal lesions, such as inflammatory polyps. The necrosis associated with these types of lesions suggests aggressive behavior and highlights the need for early diagnosis and appropriate treatment. In this report, we present a clinical case that underscores the complexity in evaluating and managing these rare neoplasms, with the aim of contributing to clinical and surgical knowledge in the field of coloproctology.

Methods/Interventions: We present the case of a 65-year-old male patient with a two-month history of a foreign body sensation in the rectum, prolapsing during defecation with spontaneous reduction. The patient reports a progressive increase in the size of the lesion, requiring manual reduction in recent weeks. In the last 24 hours, he experienced an inability to reduce the prolapse, accompanied by severe pain (VAS 8/10) and changes in the coloration of the prolapsed mass. On physical examination, a giant rectal polyp approximately 6 x 6 cm with signs of necrosis was diagnosed, attached to a 3 cm pedicle, located on the posterolateral left side of the rectum, 4 cm from the anal margin. An emergency surgical intervention was performed, with a transanal resection of the polyp from its base, which appeared to originate from the muscular layer. The pathology report revealed a high-grade spindle cell malignant neoplasm, with a differential diagnosis of gastrointestinal stromal tumor (GIST).

Results/Outcomes: In this case, the patient presented with rectal prolapse with necrosis, an unusual manifestation that differs from the typical symptoms of malignant rectal tumors, which include bleeding, pain, and changes in bowel habits. The presence of a giant prolapsed polyp with inability to reduce and necrosis underscores the aggressive nature of this pathology, suggesting a high risk of complications such as tissue ischemia or perforation. Early diagnosis is crucial due to its malignant behavior and rapid progression of the disease. In this context, physical examination and direct visualization of the lesion are essential. The differential diagnosis of spindle cell neoplasms includes other types of mesenchymal tumors, such as gastrointestinal stromal tumors (GISTs), sarcomas, and other submucosal tumors. Immunohistochemical analysis is key to distinguishing these entities. In the presented case, the diagnosis of high-grade spindle cell neoplasm raised the possibility of a GIST, highlighting the importance of conducting additional studies to characterize the lesion at the molecular level, such as detecting mutations in the KIT or PDGFRA genes. Regarding treatment, surgical resection remains the cornerstone in the management of these neoplasms, especially in localized lesions.

Conclusion/Discussion: Early and accurate diagnosis of this type of neoplasms with unusual presentations is crucial, requiring a high index of suspicion and a multidisciplinary approach. Timely identification is not only essential to prevent severe complications such as ischemia or perforation but also to determine the appropriate therapeutic strategy. Surgical resection remains the cornerstone of treatment. This work invites reflection on the importance of interdisciplinary collaboration in clinical practice to improve outcomes for patients with malignant rectal neoplasms.