Expression of Early Growth Response 3 in Skin Cancers.

Objective: To assess the expression of early growth response 3 (EGR3) in normal skin and different types of skin tumors: cutaneous squamous cell carcinoma (cSCC), basal cell carcinoma (BCC), melanoma (MM), and cutaneous adnexal tumors containing sebaceous carcinoma (SC), trichoepithelioma (TE) and clear cell hidradenoma (CCH).

Background: EGR3, expressed in multiple organs, including skin, plays an important role in cell differentiation and tumor growth. Previous studies have shown that EGR3 suppresses tumor growth and is downregulated in various malignancies. However, its distribution in normal skin and its expression especially in skin tumors have not been studied.

Materials and methods: Samples of normal cases (n = 4), cSCC (n = 12), BCC (n = 12), MM (n = 12), SC (n = 4), TE (n = 4), and CCH (n = 4) were collected from patients treated in our department between 2018 and 2023. Immunohistochemistry was used to investigate the expression of EGR3. The results were analyzed with the description of the staining pattern and the histochemical score.

Results: Immunohistochemical staining showed that EGR3 was uniquely expressed in normal skin in the granular layer and upper part of the stratum spinosum, as well as in sebaceous glands and hair follicles, but not in sweat glands. In skin cancers, BCC, SC, and TE showed positive EGR3 staining, whereas cSCC, MM, and CCH were negative.

Conclusions: EGR3 has a specific expression pattern in normal skin and in skin tumors, which is important for the differential diagnosis of skin tumors, in particular for cSCC and sebaceous gland carcinoma.