case_images: PMC6222076_01
case_images: Nodular cystic lesion in the right posterolateral region of the anus.
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case_images: It was covered by a normal epidermis, with no ulcerations or signs of bleeding (Fig. 1).
case_images: (A, B) Magnetic resonance imaging of the pelvis with a single cystic, nodular image.
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case_images: PMC6222076_01_gr2.jpg
case_images: fig0010
case_images: The examination also showed that the lesion measured 2.5 x 1.7 x 2.2 cm, was not invading the sphincter muscle and rectal wall, and did not involve the coccyx or regional lymph node (Fig. 2A, B).
case_images: Nodular cystic excision.
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case_images: fig0015
case_images: She was administered spinal anesthesia in the lithotomy position to excise the nodule; 1 cm circumferential safety margins were preserved (Fig. 3).
case_images: (A, B) Histology demonstrating squamous lesion with trichilemmal keratinization and largely comprised squamous cells with abrupt keratinization and containing hyaline areas.
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case_images: Histopathological examination of the excised specimen revealed a squamous lesion with trichilemmal keratinization and largely comprised squamous cells with abrupt keratinization and containing hyaline areas (Fig. 4A, B).
case_images: (A, B) Ki-67 demonstrated low mitotic index and CD34 expression, to differentiate the PTC from squamous cell carcinoma, also confirmed the diagnosis of trichilemmal cysts.
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case_images: PMC6222076_01_gr5.jpg
case_images: fig0025
case_images: CD34 expression, to differentiate the PTC from squamous cell carcinoma, also confirmed the diagnosis (Fig. 5A, B).