PMC9886092_01
The histopathological and immunohistochemical features of Case 1 diagnosed as TLC. (A) The histopathological features of the surgical resection specimen of Case 1. The scale bar of the pathological overview picture is 1,500 mum, and the scale bars of the enlarged field of view are 200 and 100 mum, respectively. The pathological features in the solid and dashed boxes have been further zoomed in and displayed. The red dashed circle indicates the focal necrotic area visible within the tumor. The black dashed box shows mitosis (red arrows) and a large number of polygonal, transparent tumor cells (black arrows). The yellow dashed box shows a typical histopathology of trichilemmal keratinization (green arrows) and cellular atypia. The blue dashed line indicates the peripheral palisading of clear cells. The blue solid box shows the tumor invasion. (B) The staining features of Case 1. Case 1 showed positivity for PAS staining. As for immunohistochemical staining, Case 1 showed positivity for Ki-67 (60%+), Pan CK, EMA, p53, and p63 but negativity for CEA and S-100. The scale bar is 200 mum.
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Hematoxylin-eosin (HE) staining revealed the infiltrative growth of the lesion ( Figure 1A ). The cytoplasm of tumor cells was clear (indicated by black arrows) and PAS-positive ( Figure 1B ), accompanied by scattered atypical nuclei and high mitotic index (indicated by red arrows). Figure 1B ). For tumor cells seen at the bottom margins, further extended resection was performed and achieved tumor-free margins.
Radiology and histopathological features of Case 2 diagnosed as TLC. (A, B) MRI images of Case 2, taken respectively at her 57 (A) and 58 (B) years old, showing TLC nodules in the occipital region inside the red dotted circle. (C) The Emission Computed Tomography image of Case 2 showed that the bones of the whole body were not invaded by any tumor. (D) The histopathological features of Case 2. The scale bar of the pathological overview picture is 2,000 mum, and the scale bar of the enlarged field of view is 100 mum. The pathological features in the solid boxes have been further zoomed in and displayed. The lesion had many polygonal transparent tumor cells (indicated by black arrows), trichilemmal keratinization (indicated by green arrows), and calcification (indicated by blue arrows). (E) The staining features of Case 2. Case 2 showed positivity for PAS staining. As for immunohistochemical staining, Case 2 showed positivity for Ki-67 (35%), p53, and p63 but negativity for p40, HMB45, S-100, and EMA. The scale bar is 100 mum.
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Two years after the resection, head magnetic resonance imaging (MRI) detected an abnormal signal of 1.7 x 1.2 cm in left occipital subcutaneous without invasion to the skull or brain ( Figure 2A ). Another year later, MRI reported an abnormal signal of 1.8 x 1.3 cm in left occipital subcutaneous, whose imaging appearance was similar to that of 1 year ago ( Figure 2B ). No bone metastases were found by emission computed tomography (CT) ( Figure 2C ). After resection, pathological examination revealed that the tumor was attached to the epidermis with 2.2 x 2.0 x 1.5 cm in size ( Figure 2D ). The lesion had a classic presentation of TLC with many polygonal transparent tumor cells (indicated by black arrows), trichilemmal keratinization (indicated by green arrows), and calcification (indicated by blue arrows) ( Figure 2D ). PAS staining was positive ( Figure 2E ). Immunohistochemistry staining showed positivity for Ki-67 (35%), p53, and p63 but negativity for p40, HMB45, S-100, and EMA ( Figure 2E ).
PMC9886092_02
The histopathological and immunohistochemical features of Case 3 diagnosed as TLC. (A, B) Macroscopic and dermoscopic view of the TLC lesion of Case 3. (C) The histopathological features of Case 3. The scale bar of the pathological overview picture is 1,000 mum, and the scale bar of the enlarged field of view is 100 mum. The pathological features in the solid and dashed boxes have been further zoomed in and displayed. The lesion had many polygonal transparent tumor cells (indicated by black arrows) and pathological mitosis (indicated by red arrows). The blue dashed line indicates the peripheral palisading of cells. (D) The staining features of Case 3. Case 3 showed positivity for PAS staining. As for immunohistochemical staining, Case 3 showed positivity for Ki-67 (80%+), Pan CK, CK5/6, p53, p63, and EMA but negativity for CK7, CK20, CEA, HMB45, S-100, and CgA. CD34 was diffusely expressed. The scale bar is 100 mum.
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An 84-year-old woman presented with a dark-brown papule on right breast, with rough surface, uneven pigmentation, and clear boundaries ( Figure 3A ). Dermoscopy showed the nodule was an asymmetrical, multi-lobed lesion with crystalline pupa-like structures distributed ( Figure 3B ). HE staining manifested several features supporting a diagnosis of TLC:predominantly clear cytoplasm within the tumor cells (indicated by black arrows), many cells in mitosis (indicated by red arrows), and focal peripheral palisading (indicated by blue dashed line) ( Figure 3C ). PAS staining was positive ( Figure 3D ). Immunohistochemistry staining ( Figure 3D ) showed positivity for Ki-67 (80%+), Pan CK, EMA, CK5/6, p53, and p63 but negativity for CEA, CgA, CK7, CK20, HMB45, and S-100.