Keratoacanthoma: A deficient squamous cell carcinoma? Study of bcl‐2 expression

Abstract

Ten keratoacanthomas with both proliferative and regressive histologic features along with 10 well‐differentiated squamous cell carcinomas were examined using immunohistochemistry for the expression of bcl‐2, a protooncogene recently recognized to be involved in protecting cells from undergoing apoptosis. The squamous cell carcinomas had a modest but diffuse staining pattern, while the proliferative keratoacanthomas stained only at the basal cells and only rare cells stained positively in the regressive keratoacanthomas. The degree and pattern of staining suggest a loss of bcl‐2 expression with tumor maturity in keratoacanthoma and a possible role in their ultimate involution. Sleater JP, Beers BB, Stephens CA, Hendricks JB. Keratoacanthoma: A deficient squamous cell carcinoma? Study of bcl‐2 expression.

Histogenesis of keratoacanthoma: histochemical and immunohistochemical study

“…7,47,48 There are several reports of differential expression of molecular markers, such as laminin-32, nuclear factor kappa B/p50, cortactin, glut-1, Bcl-x, beta-catenin, CD44, anti-P2 X7, K10, E-cadherin, transforming growth factor-a, peanut agglutinin, peanut lectin receptor, and carcinoembryonic antigen, in KAs and SCCs. 22,31,40,43,44,[49][50][51][52][53][54][55][56][57][58][59][60][61][62] KAs were consistently positive for K6, K10, and K14. K10 and K14 were observed in specialized cells within the ORS of the hair follicle and in the interfollicular epithelium.…”

Keratoacanthoma and squamous cell carcinoma are distinct from a molecular perspective

“…24 BCL-2 is a proto-oncogene involved in protecting cells from undergoing apoptosis and has been shown to have decreased expression in regressing keratoacanthomas. 23,25 We hypothesize that prominent enrichment of the clathrin-mediated endocytosis signaling pathway may be because of granzyme-mediated apoptosis. Cytotoxic T cells and natural killer cells utilize lytic effector proteins of perforin and granzymes to eliminate target cells.…”

An immunohistochemical study of bcl‐2 protein expression in keratoacanthoma, as compared to squamous cell carcinoma and basal cell carcinoma

“…Some authors regard KA as a variant of SCC that only rarely progresses into an invasive SCC [2]. The single feature that separates KA from SCC is the involution displayed by KA [3]. KA could represent a "deficient" SCC missing a signal that would allow continued growth or protection against apoptosis and regression [3].…”

“…This protein can be detected by im- conflicting findings [3][4][5][6][7], Certain investigators have found some degree of positive staining for bcl-2 in ail of their KAs [3j or in only some of them [5]. whereas positive staining for bcl-2 was detected in all of the SCCs [3]. in only some of them [5], or in none at all [4.6,7].…”

“…Usually HES occurs early in infancy with eczematoid skin lesions c]ose]y resembling those of atopic dermatitis [3], which is more responsive to topical steroids, emollients and antihistamines, is seasonally related and when it is cornplicated with Gratiib acteria infections these tend to be more superficial than in HES [4].…”