Pulmonary mycotoxicosis: a clinicopathologic study of three cases.

Pulmonary mycotoxicosis (PM), also termed organic dust toxic syndrome or silo unloader's syndrome, is an acute illness resulting from massive inhalation of microbial toxins in organic dusts. It has not been well described histologically. Three cases of PM are presented in this report. Open lung biopsies were examined in each case. All of the patients were farmers with no prior lung disease. One had burning in his eyes, throat, and chest after exposure to moldy silage; chills, fever, dry cough, malaise, and weakness developed within 24 hours. Two patients presented with fever, progressive dyspnea, cough, and fatigue within 24 hours of emptying a corncrib, cleaning a chicken coop, and baling hay. Bilateral alveolar and interstitial infiltrates on chest roentgenograms and leukocytosis with neutrophilia were observed in all of the three patients. Two patients became hypoxemic and required mechanical ventilation. Histologic examination showed acute and organizing diffuse alveolar damage in two biopsy specimens and an acute bronchopneumonia in the third. One specimen had 1- to 10-microm ovoid organisms demonstrable with methenamine silver stains; cultures grew Fusarium and Penicillium species. The other two biopsy specimens had negative tissue cultures and special stains for organisms, although Penicillium species were grown from a preoperative bronchoalveolar lavage in one case. The two patients on mechanical ventilation recovered completely with high-dose steroids. The third patient recovered without steroids. No patient had residual functional deficits or chest radiographic abnormalities. PM can be distinguished from allergic and infectious diseases common in individuals exposed to large amounts of organic dust by its clinicopathologic features.