PMC7596012_01
Initial MRI of the pelvis. A: Axial T1, B: Coronal T2. T1 hypo intense and T2 bright/hyperintense well-defined mass arising from the left anterior rectal wall with luminal narrowing. The mass has peripheral areas of hypointense signals highlighting a more fibrous nature. There is a marked displacement of the bowel loops with a moderate amount of compression on the posterior bladder wall. No local infiltration is evident.
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The suspected differential diagnosis included a lymphoma or sarcoma (Fig. 1).
Macroscopic appearance of the tumor after initial resection. A showing left colon with rectum and cystic lesion at the rectum.
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The tumor showed a capsular sheath with focal white fleshy areas of hemorrhage and necrosis (Fig. 2).
Histopathological examination of the tumor. A: Image of hematoxylin and eosin (HE) staining with highly atypical tumor cells with abundant eosinophilic cytoplasm, irregular and hyperchromatic nuclei. B: Image of HE staining showing malignant spindled cells with elongated, slightly anisomorphic nuclei and wavy-shaped cytoplasm. C: Immunohistochemical analysis revealed positivity of the tumor cells for desmin. D: Immunohistochemical analysis for S100 showed individual tumor cell positivity.
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MyoD1 as well as strong nuclear positivity for p53 in most of the tumor cells (Fig. 3). MDM2 was only focally and weakly positive, while no reactivity for CDK4, DOG-1, CD117 and beta-Catenin was found.
CT scan of the abdomen. A: Primary tumor near the urinary bladder. B-E showing almost same level (near stoma) at different phases of treatment. B: after initial resection. C: during radiation. D: Ileus before second surgery. E: After second tumor reduction.
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However, during the first follow-up, CT scan of the abdomen reported a huge abdominal mass (13 x 18 cm) occluding the stoma with resultant ileus (Fig. 4).