[Origin of macular amyloidosis. Apropos of 160 cases]

This study is based on clinical findings in 160 patients with skin-limited amyloidosis: 151 macular, 8 biphasic and 1 lichen amyloidosis. 82.5 p. 100 of the patients were women and 17.5 p. 100 were men. 95 p. 100 of the patches were located in the back and 64 p. 100 in the suprascapular region. No less than 88 p. 100 of the patients had pruritus on the patches or on other sites. 75 p. 100 had allergic diseases or a history of allergy, and 45 p. 100 had non-allergic pruriginous diseases. Signs of scratching were noted in most of the patients. The principal causes of pruritus were dermographism, photodermatitis and dermatitis. Macular amyloidosis is now considered as secondary to scratching motivated by pruriginous diseases and not as a primary condition as hitherto described. The term "scratch amyloidosis" is proposed for macular and lichenoid amyloidosis, and the existence of a "preamyloidotic" histological stage is described.