PMC7007035_01
Clinical and imaging characteristics. A) Clinical examination evidencing a nodular lesion on the scalp, with a smooth surface and flexible skin, without abnormalities or phlogistic signs. B) Ultrasonography showing a cystic lesion with a heterogeneous solid area, in addition to hyperechoic areas
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The skin was flexible and clear without phlogistic signs (Figure 1A). Ultrasound examination (USG) revealed a heterogeneous, well-delimited solid and cystic lesion with hyperechoic areas, measuring 38 x 33 x 34mm (Figure 1B).
Perioperative characteristics. A) Intraoperative aspect of lesion resection. B) Macroscopic aspect of the specimen at cut surface evidencing a cystic cavity with brownish content and lumpy walls with a whitish solid area inside
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Macroscopy revealed a solid and cystic lesion measuring 4.5 x 4.0 x 2.0 cm, in contact with the dermis in its superficial portion and with a fascial layer at its base (Figure 2A). The open lesion revealed a cystic cavity with lumpy walls, brownish exudate, and a whitish solid nodular formation on one of the walls, measuring 1.0 x 1.0 cm (Figure 2B).
Microscopic appearance of the lesion by the Hematoxylin & eosin staining. (A, x20) Panoramic photo showing cystic lesion (arrow) located in the subcutaneous tissue showing a scaly coating with trichilemmal keratinization (B, x40) characterizing the diagnosis of proliferating trichilemmal cyst. The squamous cell blocks in the proliferating component show no cytological atypias
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The cystic lesion presented a scaly coating with abrupt trichilemmal keratinization (Figure 3A). In the solid area, a proliferation of multiple lobules of squamous epithelium without atypia was found, presenting only rare mitotic figures without invasion of adjacent tissues (Figure 3B).