Large cell acanthoma: a debate throughout the decades

Commentary | Dermatol Pract Concept 2013;4(1):5 43 Have we really concluded what a large cell acanthoma is? Is it a distinct entity, a solar lentigo, a subtype of seborrheic keratosis, or an HPV-induced acanthoma? In 1970, large cell acanthoma (LCA) was first described by Pinkus, as a sharply demarcated, hyperkeratotic patch, often on sun-exposed skin, characterized by extraordinarily large cells with polyploidy [1]. LCA presents sharply demarcated hyperorthokeratosis, hypergranulosis, and enlarged keratinocytes without signs of atypical mitoses or nuclear dysplasia. Pinkus separated actinic keratosis from LCA by its tendency towards invasion, and postulated that LCA may be a variant of lentigo senilis or that lentigo senilis may evolve into an LCA [1]. The prevalence of this, by that time, newly described entity seemed to be low, according to a retrospective histopathologic analysis held at the Department of Dermatology, University of Cologne, in which 4 cases of LCA out of 4268 cases of actinic and seborrheic keratoses were identified [2]. Since its original description, a debate in the literature has occurred as to whether LCAs are distinctive lesions or solar lentigos with large nuclei. In 1988, Sánchez Yus et al. discussed that the nature of LCA, mostly based on the frequent disordered arrangement of the malpighian cells, the nuclear variability and the occasional finding of dyskeratoses and suprabasal mitoses, and concluded that LCA is probably a cytologic variant of Bowen’s disease [3]. In 1992, there was a long, constructive series of papers published in the April issue of the American Journal of Dermatopathology, analyzing the concepts for the origin of LCA. Rabinowitz and Inghirami claimed that LCA was a distinctive keratosis, different from solar lentigo on the basis of the lack of color, absence of elongated hyperpigmented hockey-stick-shaped buds, and presence of hyperploid keratinocytes [4]. Sánchez Yus et al. concluded that LCA is a distinctive entity with various stages of development, probably related to stucco keratosis, but histologically separate from solar lentigo [5]. On the other hand, Roewert and Ackerman stated that LCA is a variant of solar lentigo and that solar lentigo (including the large cell variant) is a stage in the evolution of reticulated seborrheic keratosis and of lichen planus-like keratosis [6]. The origin of LCA still remains unclear or not well understood. During the last decade, in a small series of papers, a Large cell acanthoma: a debate throughout the decades