Large cell acanthoma. A cytologic variant of Bowen's disease?

Although it was first described by Pinkus in 1970, the entity known as large cell acanthoma (LCA) has been largely ignored. In this paper, we review the clinical and histopathologic features of 11 solitary and three multiple cases of LCA. We also compare this series with two previous reports, one by Rahbari and Pinkus and one by Rabinowitz. From the analysis of these 70 cases, we conclude that although LCA is not uncommon (it occurs in 1-2.55 per 1,000 cutaneous biopsies), as an asymptomatic, slightly keratotic lesion, usually less than 10 mm in size, it has been largely underestimated. It is more common in women than in men and mainly affects middle-aged and elderly patients. LCA is found mainly on the face and upper limbs yet in the multiple cases, the lesions seem to occur on the limbs and the back. Histologically, it can be distinguished by the large size of the malpighian cells, both nucleus and cytoplasm. The lesion is sharply limited from normal epidermis and usually shows acanthosis, hypergranulosis, and hyperorthokeratosis. Finally, we discuss the nature of LCA. Based on the frequent disordered arrangement of the malpighian cells, its nuclear variability and the occasional finding of dyskeratoses and suprabasal mitoses, as well as the involvement of skin appendages, we conclude that LCA is probably a cytologic variant of Bowen's disease.