PMC10106615_01
A 2.2 cm cystic lesion at the right flank isolated in the subcutaneous fat layer.
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On the computed tomography (CT) scan, a 2.2cm cystic mass in the subcutaneous tissue was observed ( Figure 1 ).
Representative H&E images of the tumor. (A) An infiltrative tumor with connection to cystic lining with high grade squamous intraepithelial lesion (x 100). (B) the tumor cells showed severe nuclear atypia and clear, vacuolar cytoplasm (x 800). (C) adjacent squamous cell carcinoma in situ lesion with no direct connection to normal skin epithelium (x 200). (D) cells with clear squamous differentiation and keratin pearl (arrow, x800).
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The nuclei showed severe nuclear atypia and partial basaloid features ( Figures 2A, B ). A lesion corresponding to squamous cell carcinoma in situ was also observed at the edge of the main lesion, but no connection with normal skin epithelium was observed ( Figure 2C ). In some areas, cells with clear squamous differentiation were observed and cells containing keratin pearl were also noted ( Figure 2D ).
(A, B) Immunohistochemistry showing diffuse strong positivity of the tumor cells for p63 (A) and bcl-2 protein (B) (x200). (C, D) EMA stain revealing focal positivity in well differentiated cells (C) and corresponding H&E image (D) (x200).
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In immunohistochemical staining, the cells of the lesion showed diffuse strong positivity for p63 and bcl-2 while epithelial membrane antigen (EMA) was positive only in well differentiated squamous cells ( Figure 3 ).