Macular amyloidosis, notalgia paresthetica and pruritus: three sides of the same coin?

Abstract

J.D. Bernhard, MD, Division of Dermatology, University of Massachusetts Medical Center, Worcester, MA 01655 (USA) Dear Sir The picture of ‘brownish macules showing a rippled surface’ on the back of the patient with cutaneous amyloidosis reported by Barnadas et al. [1] is striking because the appearance, location and long history of localized pruritus are virtually identical to what is seen in notalgia paresthetica [2-4]. The latter – an abnormal and usually intensely pru-ritic sensation of the back – is thought to represent an isolated sensory neuropathy. Formerly considered uncommon, it has been reported under a variety of names in case reports over several decades. These include ‘puzzling posterior pigmented pruritic patches’, ‘peculiar spotty pigmentation’, ‘hereditary localized pruritus’ and, in one case which we reported and now recognize as probably the same thing, ‘recurrent lichen simplex chronicus’ [5]. One interpretation of the case presented by Barnadas et al. is that 20 years of itching and scratching played a causative role in the appearance of cutaneous amyloid deposits at the site on the back. This is certainly consistent with current theories which suggest that repeated friction or other trauma to the skin may lead to the deposition of significant amounts of degenerated keratin, which Hashimoto has proposed calling ‘amyloid-K’ [6-8]. One must wonder how many cases of macular amyloidosis of the back are in fact due to, or identical with, notalgia paresthetica. Recognition of this entity is important not only because correct diagnosis can prevent excessive diagnostic evaluation, but because treatment with topical capsaicin cream may be helpful in many cases [9]. References 1 Barnadas MA, Perez M, Esquius J, Curell R, de Moragas JM: Papules in the auricular concha: Lichen amyloidosus in a case of bipha-sic amyloidosis. Dermatologica 1990;181:149-151. 54 Letters to the Editor