Clinical history: 60 year old female with pearly nodular skin lesion on cheek
What is the most probable diagnosis?
Nodulocystic basal cell carcinoma
This is the most common cutaneous malignancy. It commonly occurs in sun exposed skin of adults. The classic presentation is an ulcerated papule or nodule with a pearly, telangtiectatic border.
These tumors are known for local recurrence or tissue destruction rather then metastasis. There are several histopathologic types of basal cell carcinoma; the most common being nodulocystic (75%).
Histologically the tumor consists of a dual population of fibrous stroma surrounding islands of dependent cells that resemble those of the basal layer of the epidermis and hair follicle.
On lower power one can appreciate large basilar lobules of varying shape and size that form a relatively circumscribed mass. One can appreciate peripheral palisading of cells.
One can also often note cleft-like spaces that separate portions of the tumor from the adjacent fibromyxoid stroma.
These are present because fixation results in mucin shrinkage with separation of tumor lobules from the associated stroma.
The tumor is believed to be derived from an undifferentiated pluripotent epithelial germ cell. Immunohistochemistry reveals BerEP4, androgen receptor, Bcl-2, and SMA positivity, which can be used to differentiate this tumor from a trichoepithelioma.