Acquired elastotic hemangioma-like changes and eccrine sweat duct squamous metaplasia in lichen simplex chronicus/prurigo nodularis-like lesions of the knee and elbow

Background: The so-called acquired elastotic hemangioma (AEH) represents a peculiar vascular lesion affecting the sun-damaged skin of the extensor surface of the forearms or the lateral aspect of the neck of middle-aged or elderly women. Methods: This is a clinicopathological and immunohistochemical study of a series of 6 lesions located on the knee or elbow showing epithelial features of lichen simplex chronicus (LSC)/prurigo nodularis (PN) with a marked subepidermal vascular proliferation closely resembling AEH. Results: Microscopically, all cases of cutaneous lesions showed epithelial features of LSC/PN, that is compact hyperkeratosis with focal parakeratosis, irregular acanthosis, prominent hypergranulosis. Moreover, a marked subepidermal vascular proliferation arranged in a horizontal band closely resembling AEH was detected in these lesions. Another common histopathological finding was eccrine duct squamous metaplasia and/or hyperplasia. Conclusions: While AEH represents a distinctive clinicopathological variant of hemangioma characteristically appearing on sun-exposed areas of middle-aged or elderly patients, the herein described lesions seem to be non-neoplastic epithelial, vascular and eccrine sweat duct reactive changes which are likely to be associated with chronic pressure or repeated mechanical stimulation with a marked predilection for the knee and elbow.