[Lupus erythematosus and papules. 4 cases]

Papular skin eruptions are uncommon in lupus erythematosus (LE), and their occurrence may suggest several diagnoses. We report four cases of papular eruptions in LE patients. Two of these patients had purely lupoid papules on acute LE in one and on chronic LE in the other. In the remaining two cases the papules were formed by mucinous deposits that were either secondary to LE or belonged to an associated primary mucinosis. These four cases prompted us to discuss the significance of papular eruptions in lupus erythematosus. LE-specific papular manifestations have a purely lupoid histological and immunopathological substratum. In systemic LE, the frequency of these manifestations varies from one series to another, but they seem to rank fourth after vespertilio, alopecia and photosensitivity. The papules vary in size and number, and they usually complicate a severe and active systemic LE. In chronic LE, a papulo-nodular eruption may be observed, but this is even rarer. Papules occurring in the course of LE may suggest a diagnosis of mucinosis, this disease being either secondary to, or associated with LE. Secondary mucinosis is intricated with LE-specific histological abnormalities. It appears as a symptomatic alcianophilic deposit induced by cytological alterations in some dysimmune collagen diseases, such as dermatomyositis or LE. In the literature, three cases of mucinosis secondary to LE are well documented, and to these we add a fourth case in which the papules contained lupoid lesions and a variable amount of dermal mucinous deposit. The literature has also yielded sixteen cases of primary papular mucinosis associated with systemic LE (12 cases) or chronic LE (4 cases); we add to these a case of systemic LE in which the papular eruptions varied in course, density and size of the papules. As in isolated papular mucinosis, histology regularly shows a copious mucinous deposit. When present, the LE-specific skin manifestations are clearly distinct from those of mucinosis (except for the above-mentioned cases of papular lupus). The course of papular mucinosis usually runs parallel to that of LE which is characterized by its severity and its articular, haematological and renal manifestations. Analysis of the literature also provides various anatomico-clinical elements which help in differentiating between isolated papular mucinosis and primary papular mucinosis associated with LE. In the majority of cases treatment relies on corticosteroid therapy or synthetic antimalarial agents, but the results are irregular since LE seems to be more resistant to treatment than mucinosis.(ABSTRACT TRUNCATED AT 400 WORDS)