[Cutaneous manifestations of malabsorption diseases (author's transl)].

Malabsorption (M) is characterized by absorption defect of one or several nutriments in small bowel. Its clinical expression is rarely obvious and biological signs are: anaemia, low serum protein, albumin and lipid rates, low serum calcium, phosphorus and potassium level, and hypoprothrombinaemia. But only 4 simple and reliable tests are needed for diagnosis: i. e.: daily faecal fat amount measurement, daily faecal nitrogen excretion, the xylose test and the Schilling's test. This syndrome is related to many conditions which can be divided into 2 groups with and without intestinal abnormalities. The relationships between M and skin diseases belong to 4 types (J. Marks and S. Shuster): 1) M is responsible for the cutaneous signs, 2) M is caused by a skin disease, 3) both M and skin disease are the result of a same cause, 4) M and skin disease are associated in an indirect way. Only the two first types are dealt with in this report. Skin manifestations occur as a complication in 10 p. 100 to 20 p. 100 of cases of M. They are mostly polymorphous or non-specific, as they are related to multiple vitamin or essential amino acid deficiencies and heal with the treatment of M. The main conditions encountered are diffuse pigmentation, acquired ichthyosis, follicular keratosis, nail brittleness and hair loss. Mucous membrane lesions, purpura and eczematoid or psoriasis-like dermatitis have also been described. More uncommon are clubbing of fingers, finger print abnormalities, kwashiorkor or acrodermatitis enteropathica-like eruptions. The dermatogenic enteropathy, i. e. a M syndrome due to a skin disease, occurs as a result of widespread involvement of the body for instance in psoriasis or eczema; its clinical expression is rarely obvious, the histological record of gut biopsy usually normal and the results of biological tests often dissociated, but steatorrhoea is frequently found. The pathogenesis of the condition is still unknown but its importance is related to the extent of the skin disease and it only improves with the treatment of the latter. All these features and others are discussed in the report with a comprehensive review of the literature.