case_images: PMC8452038_01
case_images: The medical history of the patient.
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case_images: Moreover, a mass was also observed on the ipsilateral neck (Figure 1).
case_images: Dermatological examination. (A) A reddish, tender mass 12 cm x 10 cm in size was observed. (B) An ulceration 1 cm x 1 cm in size was found in the center of the mass. (C) The forehead was unevenly thickened and hardened, and there was an irregular soft tissue shadow on the left posterior cervical area that may have been neoplastic lesions.
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case_images: f2
case_images: Physical examination revealed multiple interfused reddish, tender plaques and nodules, which were 12 cm x 10 cm in size on his scalp (Figure 2A). The lesions had a 1 cm x 1 cm ulceration in the center (Figure 2B). Magnetic resonance imaging found that the forehead was unevenly thickened and hardened, and there was an irregular soft tissue shadow on the left posterior cervical area that may have been neoplastic lesions (Figure 2C).
case_images: Histopathological examination revealed that the nodule exhibited epithelial tumor islands interspersed with a dense fibrous connective tissue stroma and centrally located trichilemmal keratinization. (A-1) At higher magnification, the tumor had polygonal cells, palisade arrangements with focal inversion, a thick hyaline membrane surrounding each lobule, and atypical cytology. A high mitotic index and atypical mitotic figures were observed. (A-2) The presentation of the plaque and the mass on the neck was distinct from that of the nodular lesion on the scalp. There were some cable-like structures, which may have even reached from the dermis to the subcutaneous fat in the mass on the neck (B-1, B-2, C-1, C-2).
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case_images: f3
case_images: Histologically, the nodule was a classic presentation of TC, whereas the plaque and the mass on the neck presented with some cable-like structures, which looked like sweat glands in the dermis of the lesion and may even have invaded from the dermis to the subcutaneous fat (Figure 3).
case_images: Immunohistochemical staining showed that all the lesions expressed PCK, CK5/6, P63, and P53, but was Ber-EP4-negative. The plaque on the scalp and the mass on the neck also showed CAM5.2, CK7, CEA, and EMA were negative, and S-100 was negative in the nodule of the scalp and the mass of the neck. CD34 was only expressed in nodules on the scalp and was negative in plaques on the scalp and masses on the neck.
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case_images: f4
case_images: However, the immunohistochemical results of all the specimens were consistent with trichilemmal differentiation (Figure 4).