PMC4448066_01
Macroscopic view of the excised lesion. The original epidermal cyst was almost entirely replaced by the basal cell carcinoma, which had both a cystic (yellow arrow) and solid (blue arrow) component.
cde-0007-0075-g01.jpg
PMC4448066_01_cde-0007-0075-g01.jpg
F1
Macroscopically the cyst, which was 35 mm in diameter, was lined by a thick wall and contained a whitish lobulated nodule measuring 25 mm in its largest diameter (fig. 1).
At low magnification, histology shows the squamous epithelium of the epidermal cyst (light blue arrow) and the basal cell carcinoma (dark blue arrow). The yellow arrow shows the transformation point between the epidermal cyst and the basal cell carcinoma. The rest of the lesion is composed by nodulocystic basal cell carcinoma proliferation. Hematoxylin and eosin. Magnification x20.
cde-0007-0075-g02.jpg
PMC4448066_01_cde-0007-0075-g02.jpg
F2
Histology revealed a cystic basal cell carcinoma arising from the lining of an epidermal cyst (fig. 2).
Immunostaining for BerEp4, which represent a specific marker for basal cell carcinoma cells, clearly reveals the basal cell carcinoma component of the lesion (dark blue arrows). The remnant of the epidermal cyst (light blue arrow) is negative. Magnification x40.
cde-0007-0075-g03.jpg
PMC4448066_01_cde-0007-0075-g03.jpg
F3
Immunochemistry showed lack of expression of BerEp4 in the cyst's squamous epithelium but strong positivity on the nodular portion (fig. 3), in keeping with the diagnosis of basal cell carcinoma.