PMC5835006_01
Axial CT pelvis post administration of IV and oral contrast, demonstrating an exophytic mass (Yellow arrow) involving the anterior aspect of the mid and upper rectum.
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MRI (Magnetic Resonance Imaging) pelvis. CT imaging demonstrated an exophytic soft tissue mass on the anterior wall of the rectum (Fig. 1).
Sagittal T2 weighted MRI pelvis, demonstrating an intussusception of the rectosigmoid colon (Broken yellow arrow) secondary to an endoluminal soft tissue mass, which has a mixed heterogenous signal (Solid yellow arrow).
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There was no radiological evidence of metastatic disease. MRI of the pelvis demonstrated an 8.2 cm x 4.9 cm x 5.4 cm intraluminal mass causing a partial intussusception of the rectosigmoid colon (Fig. 2).
Axial T2 weighted MRI pelvis at the level of the rectum, demonstrating an endoluminal soft tissue rectal mass (Yellow arrow), which has a mixed heterogenous signal.
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T1 weighted sequence (Fig. 3), due to the melanin content of the tumour (Fig. 4). There was extension of the mass outside the bowel wall at the rectosigmoid junction, in keeping with T3 disease. This patients radiological staging was T3N0M0, given that there was no suspicious lymphadenopathy or metastatic deposits.
Resected specimen, with polypoid mass in the rectum.
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The resected specimen was sent for histopathological analysis (Fig. 5).
Normal rectal mucosa, with underlying tumour in the submucosa and muscularis propria.
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The morphological and immunohistochemical profile was consistent with malignant melanoma (Fig. 6, Fig. 7, Fig. 8).
Melan A immunohistochemistry, showing positive staining in the tumour cells.
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The morphological and immunohistochemical profile was consistent with malignant melanoma (Fig. 6, Fig. 7, Fig. 8).