PMC9250675_01
colonoscopy revealed a mass at the anorectal junction
PAMJ-41-286-g001.jpg
PMC9250675_01_PAMJ-41-286-g001.jpg
F1
Diagnostic assessment: a colonoscopy was performed with findings of an eccentric and friable mass at the anorectal region (Figure 1) which was biopsied.
hematoxylin and eosin x 1000 a) lesion comprising moderately pleomorphic cells containing Brown granular cytoplasmic inclusions original magnification x 1000)
PAMJ-41-286-g002.jpg
PMC9250675_01_PAMJ-41-286-g002.jpg
F2
The pleomorphic cells were characterized by large nuclei, prominent nucleoli with some having brown granular pigment in the cytoplasm (Figure 2).
immunohistochemistry stains x 200, cytoplasm of the malignant cells stained positive for vimentin (A), focally positive with antibodies against S-100 (B) and strongly positive with antibodies against HMB-45 (C)
PAMJ-41-286-g003.jpg
PMC9250675_01_PAMJ-41-286-g003.jpg
F3
Immunohistochemistry was positive for melanoma markers human melanoma black 45 (HMB-45), S - 100 and Vimentin (Figure 3).
MRI pelvis, sagittal T2 weighted image showing lobulated enhancing mass arising from the lower rectum close to the anal sphincter
PAMJ-41-286-g004.jpg
PMC9250675_01_PAMJ-41-286-g004.jpg
F4
The MRI pelvis revealed a 1.7 cm x 1.2 cm mildly lobulated intensely enhancing mass arising from the lower rectum close to the anal sphincter at the left lateral position (Figure 4).