[The difference forms of "parapsoriasis en plaques". A report of 90 cases (author's transl)].

The term parapsoriasis was used by Brocq (1902) to group a number of conditions previously described under different names. This group has since then been modified, the same conditions being described under separate names and these have led to a great confusion especially between countries. In this study of 90 cases, three types of parapsoriasis en plaques are distinguished. The "parapsoriasis digitiforme" (40 cases) or benign type, or xanthoerythrodermia perstans, or chronic superficial dermatitis is characterized by small, oval or finger-like, yellow or pink patches. The histology is frequently not characteristic, but in a few cases, there is an exocytosis localized "en flammèches" in the epidermis. The condition is usually permanent but none of these cases has progressed to mycosis fongoides. The parapsoriasis "en grandes plaques simples" (25 cases) is characterized by few pink patches (3 to 5), larger than in benign type. In our cases the transformation to poikiloderma atrophicans vasculare is not observed. One of these cases progressed to mycosis fongoides. The "parapsoriasis en grandes plaques poïkilodermiques" (25 cas), or poikiloderma atrophicans vasculare, prereticulotic poikiloderma, atrophic parapsoriasis, parapsoriasis lichenoides, is characterized by large patches, in limited number, showing a reticulated pigmentation and slight atrophy with telangiectasia. Five cases changed into mycosis fongoides and 4 cases showed some symptoms of malignancy; The histologic features are the same in the two last types: sometimes they are non-specific, in numerous cases the picture is characteristic with micro-abscesses or "flammèches"; in some cases there is a dense infiltrate with a clearly defined lower limit: this histologic appearance can be seen in cases without transformation into mycosis fongoides.