The Lamellar Ichthyoses

Abstract

Today, the lamellar ichthyoses form a heterogeneous group of at least six, but possibly even more types of nonbullous congenital ichthyosis. In my definition, the term “lamellar ichthyosis” is used for all nonbullous (nonepidermolytic) and isolated types of congenital ichthyoses, except for harlequin fetus. The term “lamellar ichthyosis” does not apply to self-healing collodion baby [8, 21] which historically has also been called “lamellar ichthyosis of the newborn” [8,21]. The relationship of self-healing collodion baby to lamellar ichthyosis is quite unclear. The fact that collodion baby is a transient feature of several types of lamellar ichthyosis as well as of several types of associated congenital ichthyoses [17] does not imply that self-healing collodion baby should be regarded as an ichthyosis, too. Rather, it indicates that collodion baby (Fig. 31) is a transient and in itself heterogeneous condition of the neonate that can be caused by a variety of inborn errors of epidermal metabolism. Ultrastructural studies performed by Frenk allowed the distinction between self-healing collodion baby and those types evolving into lamellar ichthyosis [8]. It is noteworthy that even among the various types of lamellar ichthyosis, collodion baby is not a constant feature and does not necessarily precede the onset of ichthyosis [17].