Diffuse febrile dermatosis in a patient with active ulcerative colitis under treatment with steroids and azathioprine: a case of Sweet's syndrome. Case report and review of literature.

Ulcerative colitis is an inflammatory bowel disease often associated with extra-intestinal manifestations, such as dermatological disorders. Of these, the most frequent are erythema nodosum and pyoderma gangrenosum, the two neutrophilic forms of dermatosis. Another is Sweet' s syndrome, which results in a sudden eruption of tender, raised erythematous or violaceous plaques/papules or nodules, less frequent vesicles, pustules or bullae, involving face, neck, arms and trunk. This skin disorder is frequently observed in patients with leukaemia or connective tissue diseases, while it is very rare in patients with inflammatory bowel disease. The present report deals with the case of a febrile diffuse skin eruption in a 53-year-old patient with moderately active ulcerative colitis after few days' treatment with steroids and azathioprine. At first, the dermatosis was addressed to an idiosyncrasy to azathioprine, which was, therefore, promptly discontinued. Histological examination of skin biopsies revealed the presence of features typical of a Sweet's syndrome. The eruption gradually improved as well as the patient's general condition, until complete regression was achieved following steroid treatment.