A 28-year-old Caucasian male presented with 3 weeks duration of left foot pain and swelling. In addition, had history of fever, malaise, generalized weakness and dry cough. Occupational history revealed exposure to soil, construction areas and handling of vegetable manure and bird droppings. Physical examination showed severe erythema, swelling and tenderness of left foot. Chest exam was unremarkable. Laboratory data included hemoglobin of 14.4, white cell count of 25,000 with 85.5% neutrophils. X-ray of left foot was normal. The patient was treated with broad-spectrum antibiotics for presumed cellulitis but had no clinical improvement. Chest X-ray revealed diffuse reticulonodular interstitial pattern bilaterally. MRI of left foot showed extensive osteomyelitis and soft tissue infection involving second through fifth metatarsals and second, third cuneiform and cuboid bones. Patient underwent bronchoscopy and also, surgical debridement of foot with bone biopsy. Cytology of bronchopulmonary tissue and histology of bone biopsy material showed broad based yeast. Culture from same material grew Blastomyces dermatitidis. Diagnosis of disseminated blastomycosis was made and patient was administered oral itraconazole 400 mg daily to be given for a total of 12 months. Five months into antifungal therapy the patient has shown significant symptomatic improvement. Blastomyces dermatitidis is a thermal dimorphic fungus endemic to Ohio, Mississippi, central and Mid-Atlantic States. The fungal mold is usually inhaled and the budding yeast may then spread hematogenously to distant organs. A retrospective study of 326 patients with blastomycosis in Mississippi from 1979-1988 was done. This study showed that majority of cases were in men (1.7:1 ratio), outdoor occupations were noted in 28.9%, diagnosis was delayed for more than a month in 43.3%, lungs were involved in 91.4%, skin in 18.1 and bones in 4.3 % cases. Bone is the third most common site after lung and skin to be involved. Osseous involvement has been estimated at 15-60% and commonly involves spine, ribs, skull, and metaphyses of long and short bones. Four basic tools for identification of the yeast include cytological, histological, wet mount evaluation and culturing. In a study of 123 patients by Lemos et al, cytological evaluation was the first to confirm diagnosis in 56.1% followed by wet mount and histology. Finding of broad based budding yeast with pyogranulomatous reaction is common. Radiography may show eccentric lucent lesions. MRI, whole body bone scan, Ga-67 citrate scans are useful in identifying disseminated lesions. Appropriate antifungal therapy has significantly reduced mortality. Current IDSA recommendation for osseous blastomycosis is 12-month therapy with itraconazole. Newer drugs in development, which show in-vitro activity against Blastomyces, include posaconazole and ravuconazole. Osseous Blastomycosis can be treated surgically and pharmacologically with excellent results. Key to early diagnosis is a complete and comprehensive history. It should be borne in mind that blastomycosis involves the lungs and bone and should be included in the differential diagnoses in appropriate cases.
Full conference title:
15th Annual Focus on Fungal Infections
- FFI 15th (2005)