Blastomycosis

Blastomycosis is an endemic mycoses in the central United States caused by a dimorphic fungus, Blastomyces dermatitidis, that exists in nature in mycelial phase and converts to yeast phase at body temperature. The organism may produce epidemics of infection following a point source of infection or sporadic endemic infection. Blastomycosis can be a subclinical illness with subsequent protection against progressive infection afforded by cellular immune mechanisms, but it may present with progressive disease with either pulmonary or extrapulmonary disease or both. Itraconazole has been shown to be the drug of choice for both infections, except in cases of life-threatening infection when amphotericin B should be used.

Deep mycotic infections in cats

A review of deep mycotic infections assessed incidence, signalment, clinical presentation, and outcome in 571 feline cases. Pertinent findings included a predisposition in young, male cats for Sporothrix schenckii and Blastomyces dermatitidis. There was an increased incidence of feline leukemia virus infection in cases with histoplasmosis and of feline panleukopenia virus infection in cases with either aspergillosis or mucoralosis. Few other predisposing conditions were identified. Cryptococcosis, coccidioidomycosis, and sporotrichosis had better prognoses for recovery. Blastomycosis, histoplasmosis, and aspergillosis commonly were disseminated infections and were associated with guarded-to-poor prognoses.

The diagnosis of deep mycoses by morphologic methods

The morphologic diagnosis of deep mycoses, although ideally accomplished by culture, often has to be made from tissue sections for smears, when cultures are not available. Especially on specimens containing necrotic foci, the use of special stains is absolutely necessary, since on hematoxylin and eosin sections many fungi cannot be seen in the necrotic debris. Stains are discussed and the results with different organisms are illustrated. Since recognition of fungi in tissues with granulomatous reaction often leads to specific and curative therapy, their identification is one of the most satisfying aspects of the surgical pathologist's work.

Comparison of the enzyme immunoassay, immunodiffusion, and complement fixation tests in detecting antibody in human serum to the A antigen of Blastomyces dermatitidis

Using a new enzyme immunoassay (EIA) and standard immunodiffusion (ID) and complement fixation techniques for antibody to the A antigen of Blastomyces dermatitidis, we tested serum from 27 patients with blastomycosis diagnosed histopathologically or by culture; 20 with diagnoses made during 1981 through 1983 (Group A) and 7 during 1974 through 1976 (Group B). We also studied 30 control subjects with Mycoplasma pneumoniae infection (17 subjects), histoplasmosis (6 subjects), coccidioidomycosis (1 subject) and no known disease (6 subjects). Detectable antibody by all 3 tests was present more often for Group A than for Group B, possibly because of delay in testing. Enzyme immunoassay was the most sensitive test; a 1:8 or greater titer was present in acute-phase serum of all Group A patients tested, and a 1:64 or greater titer was associated with disseminated disease (p = 0.003). A positive ID was also more common in disseminated (88%) than in localized (33%) disease. Enzyme immunoassay titers of 1:16 were present in 4 control subjects, 3 with histoplasmosis. The 100% predictive values of a negative EIA and positive ID suggest that these tests are useful for serologic screening (EIA) and serologic confirmation (ID) of suspected blastomycosis, particularly in disseminated disease. Enzyme immunoassay titers of 1:32 or greater strongly support the diagnosis and titers of 1:16 or less may indicate localized disease or be nonspecific. None of the serologic tests predicted disease progression or reactivation.

Blastomycosis in children

Infections due to Blastomyces dermatitidis are not commonly encountered in children and adolescents. Knowledge of the diagnosis and treatment of this disease is largely based upon experience with adult patients. We recently reviewed our experience with blastomycosis to evaluate the difficulties in diagnosis and treatment of this disease in the pediatric population. Ten patients with blastomycosis were identified during our review, and five had pulmonary disease alone. Of these five patients, four required open-lung biopsy for diagnosis, even though three had previously undergone bronchoalveolar lavage. The response to treatment with the oral azole antifungal agents (ketoconazole, fluconazole, and itraconazole) was limited, and the agent with the greatest success remains amphotericin B. Until more data are available, amphotericin B should be used for complicated and life-threatening cases of blastomycosis. If oral azole agents are used for non-life-threatening cases, patients should be followed closely, and if clinical deterioration occurs or serum levels of medications are not adequate, then amphotericin B should be substituted for the oral azole agent.

Invasive Trichophyton rubrum resembling blastomycosis infection in the immunocompromised host

A 55-year-old renal transplant recipient with onychomycosis and chronic tinea pedis presented with tender nodules on his left medial heel. He then developed papules and nodules on his right foot and calf. A skin biopsy demonstrated periodic acid-Schiff (PAS) positive, thick walled round cells, 2 to 6 microm in diameter, in the dermis. Skin biopsy culture grew Trichophyton rubrum. T. rubrum has been described as an invasive pathogen in immunocompromised hosts. The clinical presentation, histopathology, and early fungal culture growth suggested Blastomyces dermititidis in the differential diagnosis before the final identification of T. rubrum.

Pathogenesis of paracoccidioidomycosis: a model based on the study of 46 patients

Forty-six Paracoccidioidomycosis patients were studied with emphasis on lung pathology. It was found that the greatest clinical involvement of the reticuloendothelial system occurred in younger individuals. On the other hand, the frequency of tegumentary lesions was low in young patients and increased with age. Lung involvement was nearly always demonstrated when searched for and showed no relationship to the patient's age. In the young patients the disease was acute while in the older individuals its course was chronic. The findings from this study permitted formulation of a model for the pathogenesis of paracoccidioidomycosis in which the respiratory tract is accepted as the primary site of infection. Based on this model, a classification of the various forms of the entity is proposed.

Acute respiratory distress syndrome and blastomycosis: presentation of nine cases and review of the literature

Mississippi has the highest prevalence of blastomycosis in the country. In 20 years and 5 months there were 123 patients treated for blastomycosis at the University of Mississippi Medical Center. Among these, 107 patients had lung involvement and nine patients (8.4%) developed acute respiratory distress syndrome. Seven of the nine patients (78%) died of respiratory failure. In six patients, the lungs were the only organs involved. The three other patients had involvement of other organs as well. Average survival after the onset of acute respiratory distress syndrome was 6.9 days (range, 2 to 17 days). Acute respiratory distress syndrome can be triggered by pulmonary infections caused by bacterial diseases and other fungi. Massive proliferation of yeasts in the pulmonary parenchyma is the typical finding of patients with blastomycosis and acute respiratory distress syndrome. Underlying diseases that lead to immunodepression were present in only one patient and probable partial immunodepression was present in two other patients. Data from 19 other cases reported in the literature are discussed. Ann Diagn Pathol 5:1-9, 2001.

Imaging Manifestations of Blastomycosis: A Pulmonary Infection with Potential Dissemination

Pulmonary blastomycosis is an uncommon pathologic condition that is endemic to Canada and the upper Midwest of the United States. Blastomycosis has a variety of radiologic manifestations, including airspace consolidation, focal masses, intermediate-sized nodules, interstitial disease, miliary disease, and cavitary lesions. Affected patients may be asymptomatic or may present with clinical manifestations ranging from mild chronic cough to acute respiratory distress syndrome-like symptoms. Patients with acute symptoms are more likely to have airspace consolidation, whereas chronic manifestations may be associated with masslike lesions. Intermediate-sized nodules with accompanying airspace consolidation, particularly in the upper lobes, should raise suspicion for fungal disease. Lymphadenopathy and pleural effusions are quite uncommon, and calcification is not often seen. Blastomycosis may be aggressive and require treatment. Dissemination from the lung is not unusual and can involve any organ. Diagnosis is often delayed because blastomycosis can mimic many other disease processes, including bacterial pneumonia, malignancy, and tuberculosis. Radiologists can best contribute to the care of patients who live or travel in endemic areas by maintaining a high degree of suspicion for blastomycosis and being familiar with its myriad manifestations.

Lobomycosis as a disease of the Atlantic bottle-nosed dolphin (Tursiops truncatus Montagu, 1821)

Skin lesions on an Atlantic bottlenosed dolphin, captured off the coast of Florida, were investigated and found to be histologically and microbiologically indistinguishable from those caused in humans by Loboa loboi. All attempts to isolate the etiologic agent or to transmit the infection to mice and monkeys ended in failure. Sight records of other suspected dolphin cases of lobomycosis in Florida waters are described along with citations of two previously confirmed and published dolphin infections.

Pulmonary blastomycosis: radiologic manifestations

Blastomycosis, an airborne fungal disease with the lung the portal of entry, is endemic to the central and south central areas of the United States. The disease occurs in patients who range from asymptomatic to those with symptoms of acute pneumonia. Retrospective review of 27 cases from our institution revealed four well-defined radiographic patterns including air-space disease, nodular masses, interstitial disease, and cavitation. Some patients with air-space disease have symptoms of an acute pneumonia; more commonly they have no pulmonary symptoms. Air-space disease was the most frequent radiographic pattern in chronic blastomycosis with proved nonpulmonary disease; therefore, it cannot be regarded as indicative of early or acute blastomycosis. There was no relationship between the radiographic pattern and distribution, pulmonary symptomatology, or clinical stage of the disease. Our material does not support the previously suggested association of lower lobe air-space disease with early disease and upper lobe involvement with the chronic and often disseminated form. A more precise understanding of the variety of radiographic patterns and the spectrum of clinical presentations will facilitate diagnosis of pulmonary blastomycosis.

Pyogenic spondylodiskitis: a radiologic/pathologic and culture correlation study

BACKGROUND

Intervertebral disk tissue is resistant to hematogenous infection because of its avascularity. However, spondylodiskitis is being diagnosed with increasing frequency because of advancement in magnetic resonance imaging technology. There is a dearth of information regarding the bacteriology, histomorphologic features, and radiopathologic correlation of spondylodiskitis.

DESIGN

The study population consisted of 20 patients diagnosed as having spondylodiskitis by magnetic resonance imaging with and without gadolinium 67 enhancement and bone scans with technetium Tc 99m or gallium citrate Ga 67. Twenty-seven biopsy and debridement specimens were obtained from these patients. The specimens were cultured for microorganisms and also processed for histopathologic testing. Tissue sections were examined with hematoxylin-eosin and stains for infectious agents (Gomori's methenamine-silver, Gram, and Ziehl-Neelsen stains).

RESULTS

Where intervertebral disk tissue was present (23 of 27 cases), the morphologic changes included vascularization (with or without granulation tissue), myxoid degeneration, and necrosis. Chronic osteomyelitis was present in all 27 specimens and was associated with acute osteomyelitis in 7 cases (25%). Twenty-one of 27 cases had positive culture results (mostly pyogenic bacteria), but special stains revealed microorganisms in sections of the disk in only 4 cases (3 cases with gram-positive cocci and 1 with yeast consistent with Blastomyces). Florid acute inflammation was present in all the 4 cases.

CONCLUSION

Histopathologic features of acute spondylodiskitis include vascular proliferation, myxoid degeneration, and necrosis of the disk tissue with adjacent chronic osteomyelitis. Acute inflammation is variable and when florid is usually associated with identifiable organisms on histologic examination. At biopsy, tissue should be submitted for culture, since culture has a high sensitivity and specificity for detecting the etiologic organism.

Blastomycosis of the esophagus

A patient had clinical, endoscopic, and roentgenographic signs of esophageal carcinoma, but biopsies and brushings were negative. At operation he was found to have blastomycosis localized to the esophagogastric region and adjacent lymph nodes. There was no evidence of pulmonary disease. He was treated successfully by partial esophagectomy and amphotericin. The literature on esophageal blastomycosis is reviewed.

Disseminated Trichosporon beigelii (cutaneum)

Two cases of invasive Trichosporon beigelii (syn. cutaneum) infection are reported and are compared with the eight other previous reports. All affected patients were either immunosuppressed or had recently undergone a surgical procedure. The diagnosis had been delayed and the prognosis was poor. Only two patients recovered after vigorous antimycotic therapy and concomitant remission of their leukemia. A biopsy of the skin lesion, as illustrated in one of our patients, may prove to be useful in the early diagnosis.

Granuloma formation and killing functions of granuloma in congenitally athymic nude mice infected with Blastomyces dermatitidis and Paracoccidioides brasiliensis

We did this experiment to clarify the mechanism of granuloma formation and the killing functions of granuloma in nude mice against Blastomyces dermatitidis and Paracoccidioides brasiliensis infections. B. dermatitidis A-295 and P. brasiliensis B-1183 were the cultures used. Congenitally athymic nude (nu/nu) mice and their heterozygous (nu/+) littermates of BALB/c background were the test animals. From culture A-295, 0.1% and 1% cell suspensions (wet weight) were prepared and from culture B-1183 0.2% and 2% cells suspensions were prepared. Ten nu/+ and 10 nu/nu mice were allotted to each of four cell suspensions. For experimental blastomycosis each mouse was inoculated intravenously with 0.2 ml of the cell suspension of A-295 and for experimental paracoccidioidomycosis, with 0.15 ml of the cell suspension of B-1183. Two mice from each of the four groups were killed at 5, 8, 12, 18 and 25 days after inoculation, and histopathologic sections, stained with H&E or by PAS, were prepared from various internal organs. In the nu/nu mice inoculated with B. dermatitidis A-295 granuloma was formed in the brain tissue after the 12th day. However, mononuclear cells, which formed the granuloma, did not kill the fungal cells, and the fungal cells continued to multiply in the granuloma. On the other hand, in the heart, kidney and fat tissue, their histopathological findings after the 18th day were clumps of fungal cells with slight cell reactions. In these organs the exertion of cell-mediated immunity was necessary for granuloma formation against the fungal infection. In the nu/nu mice infected with P. brasiliensis B-1183, granuloma appeared in the brain and kidney after the 18th day and fungal cells continued to multiply within the granuloma as well as in those inoculated with culture A-295. These results show that the exertion of cell-mediated immunity plays an important role in the mouse's defense mechanisms against these fungal infections. We assume that the defense mechanisms of immunocompetent mice against B. dermatitidis or P. brasiliensis infection consist chiefly of two steps: in the first step phagocytosis by PMNs occurs and in the second step cell-mediated immunity enters into play.

Cerebral blastomycosis: a case series incorporating voriconazole in the treatment regimen

Cerebral blastomycosis is a rarely reported disease. We report three cases of cerebral blastomycosis previously treated with standard antifungal therapy, which were subsequently successfully treated with voriconazole. The first is a 29-year-old man who initially presented with concomitant cutaneous and osseous blastomycosis; the second is a 50-year-old man who initially presented with prostatic, pulmonary and cutaneous lesions. The third patient was a 63-year-old man who presented with hemiplegia and multiple intra-cerebral blastomycomas. This report represents the first two documented relapses, in Canada, of CNS blastomycosis following treatment with itraconazole and, to our knowledge, among the first three worldwide human cases of cerebral blastomycosis treated successfully with voriconazole.

Blastomycosis of the lumbar spine: case report and review of the literature, with emphasis on diagnostic laboratory tools and management

We report on the conservative and surgical management of a patient with blastomycosis of the lumbar spine, causing severe and crippling deformity. The diagnosis was made through biopsy. Curative removal, reconstruction and realignment of the spine were achieved. Imaging modalities were highlighted, with a detailed discussion of the histology and conservative and surgical management. We emphasize the importance of early, aggressive treatment of blastomycosis to prevent deformity and disability, and to enable identification of the best management of a destructive lesion with deformity. This case demonstrates that empirical treatment should not be used in cases of unusual sinus and abscess locations. Specific diagnosis and early treatment are indicated to prevent dreadful complications and spinal deformity resulting from blastomycosis. Aggressive antifungal therapy can cure the disease but does not control complications related to deformity. The latter can only be addressed by surgical reconstruction. We review the literature of surgical treatment, focusing on abscess drainage, bone fusion and posterior instrumentation in the absence of addressing the deformity component.

Thoracic mycoses from endemic fungi: radiologic-pathologic correlation

The endemic fungi Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides immitis are primary human pathogens whose major portal of entry is the respiratory tract. Their clinical manifestations are categorized as acute, chronic or chronic progressive, or disseminated fungal disease. Most acute pulmonary infections are self-limited, and many are asymptomatic. Chronic, progressive, or disseminated disease is much less common and most often occurs in immunocompromised patients. The radiologic manifestations of these disorders are protean. They include interstitial or air-space opacities, solitary or multiple pulmonary nodules, parenchymal masses, cavities, and hilar or mediastinal adenopathy. The diagnosis of a thoracic mycosis requires familiarity with the epidemiology of the fungus in question, the various modes of clinical presentation, and the full spectrum of radiologic manifestations. Although skin and serologic tests can be useful, definitive diagnosis requires culture of the fungus from infected tissue or demonstration of the organism at microscopic examination.

Unilateral Blastomyces dermatitidis endophthalmitis and orbital cellulitis. A case report and literature review

PURPOSE

The authors report the clinical, cytologic, and histopathologic findings of a unique presentation of concomitant unilateral endophthalmitis and orbital cellulitis secondary to Blastomyces dermatitidis.

DESIGN

Case report.

METHODS

A 29-year-old healthy woman with a history of pulmonary tuberculosis presented with a painful right eye and rapidly decreasing vision. Fundus examination showed a diffuse elevated choroidal lesion at the posterior pole. With an otherwise unremarkable systemic work-up, the patient was treated with systemic antibiotics and corticosteroids for a presumed diagnosis of choroidal tuberculous granuloma. After an initial response to the treatment, the patient's condition deteriorated rapidly with visual acuity decreasing from 20/25 to no light perception in 3 months. Ipsilateral proptosis developed with magnetic resonance imaging showing a poorly defined orbital mass. Surgical enucleation and an orbital biopsy were performed.

RESULTS

Histopathologic examination of the orbital specimen and an intact enucleated globe showed a diffuse necrotizing granulomatous process with the presence of numerous yeasts consistent with B. dermatitidis. This subsequently was confirmed by positive culture of B. dermatitidis from the orbital specimen.

CONCLUSIONS

This is a unique case of concurrent unilateral endophthalmitis and orbital cellulitis secondary to B. dermatitidis. Intraocular dissemination of blastomycosis should be suspected in the differential diagnosis of endophthalmitis in patients with previous or active pulmonary lesions of equivocal nature. Early diagnosis and prompt treatment with antifungal medications are essential.

Blastomycosis of the eyelid

BACKGROUND

Published reports indicate that eyelid involvement occurs in approximately 25% of patients with systemic blastomycosis and that mortality exceeds 60% in untreated patients. The purpose of this study is to investigate this purportedly frequent association.

METHODS

The Medical Diagnostic index of the Mayo Clinic was used to identify patients who were treated for blastomycosis from 1976 through 1993. The medical records of affected patients were reviewed.

RESULTS

Of 79 patients with blastomycosis, only 1 (1.27%; 95% confidence interval, 0.03%-6.85%) had eyelid involvement. The diagnosis of systemic disease was established in this patient after biopsy of the eyelid lesion, and the infection responded satisfactorily to treatment with itraconazole.

CONCLUSION

Contrary to previous reports, eyelid involvement with systemic blastomycosis is uncommon.