Involucrin Expression in Epidermal Tumors

Moon, Doo Chan; Hyun, Myung Ki; Kwon, Kyung Sool; Chung, Tae Ahn

Abstract

Involucrin is a recently recognized structural component of mature squamous epithelial cells and is considered as a marker of normal eratinocyte differentiation and ma.turation. In this study peroxidase-antiperoxidase techniques were used to assess involucrin expression in histologic sections of normal skin and a variety of epidennal tumors including squamous cell carcinomas(25 cases), keratoacanthomas(11 cases), basal cell carcinomas(20 cases), trichoepitheliomas(5 cases), Howens diseases(12 cases), arsenic keratoses(10 cases), actinic keratoses(10 cases) and Pagets diseases(2 cases). The results were as follows : l. In normal skin, the upper third of the viable epidermis showed diffuse cytoplasmic staining for involucrin. In hair follicles, the lower area of inner root sheath and inner area of the outer root sheath stained positively. The sebareous glands did not stain, but the ducts of sebaceous glands were positive. 2. Keratoacanthomas showed a relatively homogeneous staining pattern for inirolucrin ', all cells except basal cells stained with mild to moderate intensity. In contrast, squamous cell carcinomas disclosed a highly irregular involucrin staining pattern with marked variation in staining intensity from cell to cell. 3. Basal cell carcinomas were negative for involucrin except squamous horn cysts, and the epidermis overlying basal cell carcinomas showed the field effect, that is, the epidermis overlying the tumors exhibited diffuse, homogeneous positive staining of cells in all layers of the epidermis. 4. ln trichoepitheliomas, the involucrin reactivity was negative as in basal cell carcinoma.s, but the field effect was not observed. 5. In Elowens disease, actinic keratosis, arsenic keratosis and Pagets disease, the positivit.y for involucrin staining extended deeper into the stratum malpighii than was observed wit,h normal epidermis. And areas showing irregular patchy pattern of involucrin staining were considered to have the potentiality of malignant invasive change much more than the negative or homogeneous areas. Paget's cells were negative for involucrin as the adjoining keratinocytes in the lower portion af epidermis.