Work related acute leukemia and mucor mycosis in a boat-builder

mcreased risks for leukemia and lymphoma have been suggested in studies of workers exposed to styrene in the rubber and plastics industry.l Reportlng of anecdotal cases, with complete occupational histories, might contribute to the recognition of new causes of leukemia. In the August 1994 a 47-years-old caucasian man, boat-builder, was admitted to our Division of Hematology complaining of weakness, fever, purpura, and gingival hypertrophia. He had been exposed for 21 years to styrene in fiber-reinforced plastic shipyards as /aminator. He sprayed styrene with a gun on ship hull, provided with half-facepiece air-purifying or full-face airsupplied respirators which he shared with his co-workers. Hematologic examination showed severe leucocitosis 80x109/L (blasts 29%), severe anemia (Hb 8.4 g/dL), and thrombocytopenia (PLTs 38x109/L). Bone marrow aspirate showed 65% blasts and 30% of monocyte cells. Blasts were of medium size with loose chromatin, thin cytoplasmatic granulations peroxidase-positive and sometimes with single Auer roads. Flow cytometric immunophenotyping demonstrated expression of HLA-DR, CD13, CD33, CD11b, CD14. Cytogenetic analysis showed a normal male kariotype as 46XY. A diagnosis of Myelomonocitic Acute Leukemia (FAB M4) was made. A complete remission was induced by standard chemoterapy (ICE protocol). After chemoterapy the patient showed sepsis by Pseudomonas aeruginosa successfully treated with antibiotic therapy. During aplastic period, at the left maxillary bone occurred massive necrosis of mucosa and bone. Mucosa biopsy identified hyphae of Mucormycosis. The diagnosis was confirmed by hystological examination of mascellar and alveolar bones during maxillary surgery. Fungal infections are frequently seen in immunosuppressed patients with neutropenia or prolonged impaired T-celi function, such as bone marrow transplant recipients. Aside from common Candida and Aspergillus species, rare fungi like Mucor may be observed. Anecdotal cases of mucormycosis pneumonia are reported in patients with hematological neoplasms and iatrogenic immunosuppression after treatment.2-4 Mucor hyphae.were later demonstrated in the filter of the mask that he shared with his co-workers. Microbial growth o n respirator filters from improper storage In humid environments has been reported.s Our patie.nt, however, was the sole case of mucormycosis in the boat building factory. Antimycotical therapy with Amphotericine-B (total dose 1.34 g) was started with resolution of mycotical infection after 2 months. In the October 1995, persisting complete remission and resolution of mycotical infection, he underwent to consolidation chemotherapy. After 4 months the patient was in complete remission, so that explantation of bone marrow followed by autologous bone-marrow transplantation was done. Actually the patient is in continuous complete remission. Severa! recent studies of the reinforced plastics industry, where high exposure to styrene occurs, have suggested that workers exposed to styrene have increased mortality from lymphatic and hematopoietic cancer. A historical cohort study conducted in Denmark, Finland, Italy, Norway, Sweden and the United Kingdom involving >40,000 workers suggested an association between hematological malignancies and time elapsed since first occupational exposure to styrene, and a two-fold risk 20 years after first exposure, even lf mortality from the lymphatic and haematopoietic tlssues was non elevated,6 A Danish nested case-referent study found a 2.5-fold increased risk for myeloid leukemia wlth clonai chromosome aberrations among workers wlth styrene exposure.7 These results do not exclude the posslbility that styrene causes leukemia. Within the boat-making industry, hu/1/amination job ranks higher in exposure to styrene than other jobs, and frecjuently exceeds the NIOSH-recommended time-weighted averl:lge standard (50 ppm).B Evidence of exposure, and epidemiologica! data support the hypothesis that leukemia may have occupational origin. The case was slgnaled to the National Institute for Work Accldent and Illness (INAIL) for worker's compensatlon. Our observation points out that work-related illnesses (i.e.: leukemia and mycosis) may be seen at first and managed by physicians other than occupational medicine specialists. This may pose a knowledge barrier to recognizing occupational disease,9 This barrier may be overwhelmed via systematic referring to occupational health physicians of doubtful cases. Further epidemiologica! studies will undoubtedly lead to better knowledge of occupational causes haematological malignancies.