Musculoskeletal Coccidioidomycosis
Musculoskeletal Coccidioidomycosis
Coccidioidomycosis is a primary pulmonary infection, endemic to the southwestern United States, caused by inhalation of spores in an immunocompetent host. When systemic spread occurs, the dissemination of infection to musculoskeletal sites might account for 20% to 50% of cases. The musculoskeletal manifestations are well recognized by physicians in endemic areas. We report 2 cases encountered in metropolitan Chicago in which morphologically typical, large, yeast-like, encapsulated, endosporulating organisms were identified in tissue samples and Coccidioides immitis was cultured. One patient had a degenerative-type radiographic picture thought to be related to a sports injury. A second patient with skin lesions and a paraspinal mass required emergency decompressive spinal surgery. A history consistent with exposure to Coccidioides organisms was apparent only for the first patient. Although the diagnosis can be established morphologically by identifying the large endospores in tissue samples, the submission of samples for culture and subsequent microbiologic confirmation requires the diagnosis to be considered clinically. This report emphasizes the rarity of the organism in nonendemic areas and the redundant value of using both morphologic and microbiologic modalities.
Coccidioides immitis is a dimorphic fungus with worldwide distribution but endemic to the arid areas of the southwestern United States, Mexico, and South America. It has been estimated that there are more than 100,000 cases of coccidioidomycosis annually, although in the absence of an official national case registry, the actual number of cases is unknown. In the United States for 2004, 6,056 cases were reported to the Centers for Disease Control and Prevention, 98% of which were from California and Arizona. The appearance of cases in nonendemic areas, in the United States and elsewhere, is rare. The ease of international travel emphasizes the need for clinical awareness and diagnostic consideration of this disease, especially in nonendemic areas.
Coccidioidomycosis typically is acquired by inhalation of aerosolized spores or arthroconidia from the soil. The spores develop in the lung into large spherules, ranging from 20 to 200 B5m in diameter, which then develop endospores. The saccule containing the endospores may rupture in vivo, whereupon new spherules will develop, or the spores are released to the soil of the external environment to develop into mycelia and future conidia. Nonspecific flu-like symptoms develop in only about 40% of patients, and the remainder are asymptomatic. The mechanisms of virulence are not well understood, and the development of disseminated disease is unpredictable but may be suspected with marked elevation of the complement fixation titers. The actual incidence of systemic spread is unknown but is estimated at 1% to 5% and might correlate with high complement fixation titers. The pattern of clinical infection is analogous to that of tuberculosis, consisting of systemic dissemination from a primary lung focus. Skin, lymph nodes, musculoskeletal sites, and the central nervous system are favored foci of dissemination.
Musculoskeletal involvement is said to be unusual but, according to some authors, might account for 20% to 50% of disseminated cases. Comprehensive reviews of Coccidioides organisms causing osteomyelitis and/or synovitis report higher rates of involvement, which probably reflect the referral nature of the institutions making the reports. The favored sites are the spine and the knee. A previous assertion that monoarticular disease is more common is not supported by one recent review.
Although microbiologic culture is widely regarded as the diagnostic standard and the organism can grow easily within a few days, cultures might not always be submitted. The clinical level of suspicion may be especially low in a patient in a nonendemic area with an extrapulmonary lesion and in whom the pulmonary lesion is inapparent radiographically. Under such circumstances, a fine-needle aspiration or tissue sample will allow morphologic recognition of the large Coccidioides spherule, with or without endosporulation, even in cases of osteomyelitis and joint effusion.
We report 2 cases of musculoskeletal coccidioidomycosis, 1 in the spine and 1 in the ankle. Both patients were from metropolitan Chicago, IL, a nonendemic area for this disease. The diagnoses were established by standard histopathologic examination and supplemented by positive culture results.
Coccidioidomycosis is a primary pulmonary infection, endemic to the southwestern United States, caused by inhalation of spores in an immunocompetent host. When systemic spread occurs, the dissemination of infection to musculoskeletal sites might account for 20% to 50% of cases. The musculoskeletal manifestations are well recognized by physicians in endemic areas. We report 2 cases encountered in metropolitan Chicago in which morphologically typical, large, yeast-like, encapsulated, endosporulating organisms were identified in tissue samples and Coccidioides immitis was cultured. One patient had a degenerative-type radiographic picture thought to be related to a sports injury. A second patient with skin lesions and a paraspinal mass required emergency decompressive spinal surgery. A history consistent with exposure to Coccidioides organisms was apparent only for the first patient. Although the diagnosis can be established morphologically by identifying the large endospores in tissue samples, the submission of samples for culture and subsequent microbiologic confirmation requires the diagnosis to be considered clinically. This report emphasizes the rarity of the organism in nonendemic areas and the redundant value of using both morphologic and microbiologic modalities.
Coccidioides immitis is a dimorphic fungus with worldwide distribution but endemic to the arid areas of the southwestern United States, Mexico, and South America. It has been estimated that there are more than 100,000 cases of coccidioidomycosis annually, although in the absence of an official national case registry, the actual number of cases is unknown. In the United States for 2004, 6,056 cases were reported to the Centers for Disease Control and Prevention, 98% of which were from California and Arizona. The appearance of cases in nonendemic areas, in the United States and elsewhere, is rare. The ease of international travel emphasizes the need for clinical awareness and diagnostic consideration of this disease, especially in nonendemic areas.
Coccidioidomycosis typically is acquired by inhalation of aerosolized spores or arthroconidia from the soil. The spores develop in the lung into large spherules, ranging from 20 to 200 B5m in diameter, which then develop endospores. The saccule containing the endospores may rupture in vivo, whereupon new spherules will develop, or the spores are released to the soil of the external environment to develop into mycelia and future conidia. Nonspecific flu-like symptoms develop in only about 40% of patients, and the remainder are asymptomatic. The mechanisms of virulence are not well understood, and the development of disseminated disease is unpredictable but may be suspected with marked elevation of the complement fixation titers. The actual incidence of systemic spread is unknown but is estimated at 1% to 5% and might correlate with high complement fixation titers. The pattern of clinical infection is analogous to that of tuberculosis, consisting of systemic dissemination from a primary lung focus. Skin, lymph nodes, musculoskeletal sites, and the central nervous system are favored foci of dissemination.
Musculoskeletal involvement is said to be unusual but, according to some authors, might account for 20% to 50% of disseminated cases. Comprehensive reviews of Coccidioides organisms causing osteomyelitis and/or synovitis report higher rates of involvement, which probably reflect the referral nature of the institutions making the reports. The favored sites are the spine and the knee. A previous assertion that monoarticular disease is more common is not supported by one recent review.
Although microbiologic culture is widely regarded as the diagnostic standard and the organism can grow easily within a few days, cultures might not always be submitted. The clinical level of suspicion may be especially low in a patient in a nonendemic area with an extrapulmonary lesion and in whom the pulmonary lesion is inapparent radiographically. Under such circumstances, a fine-needle aspiration or tissue sample will allow morphologic recognition of the large Coccidioides spherule, with or without endosporulation, even in cases of osteomyelitis and joint effusion.
We report 2 cases of musculoskeletal coccidioidomycosis, 1 in the spine and 1 in the ankle. Both patients were from metropolitan Chicago, IL, a nonendemic area for this disease. The diagnoses were established by standard histopathologic examination and supplemented by positive culture results.
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