Silver-stained organizer regions and immunoglobulins in cutaneous keratoacanthomas and squamous cell carcinomas

Abstract

The aim of this study was to investigate the biologic activity of epidermal cells in keratoacanthomas (KAs) and squamous cell carcinomas (SCCs) by counting the number of silver-stained nucleolar organizer regions (AgNORs), to estimate the quantity of Ig-producing cells and the inflammatory cellular infiltrate (ICI), and to make a comparative evaluation.

Thirty KAs (10 at growth stage, 10 at mature stage, and 10 at involution stage) and 28 SCCs (nine well differentiated-Grade 1 (G1), seven moderately differentiated-Grade 2 (G2), five poorly differentiated-Grade 3 (G3), and seven pseudoadenoid) were investigated.

The KAs examined had a mean number of 1.727 AgNORs (S.D. 0.232), and IgG predominated in most cases. IgG and IgE increase at the involution, IgA remains at almost the same level, and IgM decreases during the maturity stage. The SCCs examined had a mean number of 2.105 AgNORs (S.D. 0.446). IgG predominated and gradually increased in proportion to the degree of malignancy.

There is a significant difference in the number of AgNORs and the proportion of Ig subclasses in contrast to the cellular infiltrate among the three stages of KA. In SCCs, the number of AgNORs and the percentage of Igs and ICI increased gradually in proportion to the degree of malignancy.

Introduction

Keratoacanthomas (KAs) are highly differentiated, biologically benign, non-metastasizing tumors characterized by rapid development and a tendency towards spontaneous regression [16]. Usually, the tumor develops in three stages [25], [37]. The early phase of proliferation is often difficult to distinguish histologically from squamous cell carcinoma (SCC) because high mitotic activity is observed, the degree of keratinization is still low, and nuclear atypia is common. The fully developed lesion is normally diagnosed more easily and is followed by the phase of involution with frequent detection of apoptotic cells. Invasive SCCs are also epidermal neoplastic lesions consisting of altered keratinocytes. However, it remains unclear whether the alteration of neoplastic cells in both disorders involves different inflammatory reactions and the production of immunoglobulins (Igs) [4], and whether the infiltration of reactive cells is secondary to the underlying disease or rather an active participant in determining the outcome of the neoplasia. Nucleolar organizer regions (NORs) are loops of DNA situated on the short arms of acrocentric chromosomes 13, 14, 15, 21, and 22. They can be demonstrated in formalin-fixed, paraffin-embedded sections by a one-step silver technique, the resulting black structures being termed AgNORs [2], [19], [21]. The aim of the study was to investigate the biological activity of epidermal cells in KAs and SSCs by counting the number of silver-stained NORs, to estimate the quantity of Ig-producing cells and the inflammatory cellular infiltrate (ICI) in these entities, and to make a comparative evaluation of Ig-producing cells and AgNORs in order to identify any possible mutual correlation among the expression of these parameters.