[White papulosis of the neck. Clinical aspects of pseudoxanthoma elasticum].

INTRODUCTION: Acquired elastolysis of the papillary dermis simulating pseudoxanthoma elasticum and white papulosis of the neck are two skin diseases with clearly limited borders. The two entities can be distinguished clinically when papulae converge into yellowish-white patches and histologically by complete absence of the elastic network in the papillary dermis without thickening of the collagen network in the superficial and mid dermis. CASE REPORT: We observed a patient with the clinical and histological criteria for acquired elastolysis of the papillary dermis. Histological examination showed a thick collagen network as described in white papulosis of the neck. DISCUSSION: This case clearly demonstrates the histological continuum between these two entities. A review of the literature also provided evidence of borderline forms, leading us to propose grouping them together. Elastolysis of the papillary dermis would appear to be a relatively specific histological sign differentiating white papulosis of the neck, in a general sense, and acquired elastosis of the mid dermis. Two factors could explain the rare observations of acquired elastosis of the mid dermis in patients with acquired elastosis of the papillary derma: use of the Verhoeff Van Gieson stain without an internal control and imprecise localization of the biopsy.