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Open Access Highly Accessed Case report

Coccidiomycosis infection of the patella mimicking a neoplasm – two case reports

Yi-Chen Li1, George Calvert2, Christopher J Hanrahan3, Kevin B Jones4 and Robert Lor Randall4*

Author Affiliations

1 Department of Orthopaedic Surgery, E-DA Hospital/I-Shou University, Kaohsiung, Taiwan

2 Division of Orthopaedic Surgery, Department of Surgery, City of Hope National Medical Center, Duarte, California, USA

3 Department or Radiology, University of Utah School of Medicine, Salt Lake City, Utah, USA

4 Sarcoma Services, Department of Orthopaedics, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA

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BMC Medical Imaging 2014, 14:8  doi:10.1186/1471-2342-14-8

Published: 18 February 2014

Abstract

Background

Coccidioidomycosis is an endemic fungal infection in the southwestern of United States. Most infections are asymptomatic or manifest with mild respiratory complaints. Rare cases may cause extrapulmonary or disseminated disease. We report two cases of knee involvement that presented as isolated lytic lesions of the patella mimicking neoplasms.

Case Presentation

The first case, a 27 year-old immunocompetent male had progressive left anterior knee pain for four months. The second case was a 78 year-old male had left anterior knee pain for three months. Both of them had visited general physicians without conclusive diagnosis. A low attenuation lytic lesion in the patella was demonstrated on their image studies, and the initial radiologist’s interpretation was suggestive of a primary bony neoplasm. The patients were referred for orthopaedic oncology consultation. The first case had a past episode of pulmonary coccioidomycosis 2 years prior, while the second case had no previous coccioidal infection history but lived in an endemic area, the central valley of California. Surgical biopsy was performed in both cases due to diagnostic uncertainty. Final pathologic examination revealed large thick walled spherules filled with endospores establishing the final diagnosis of extrapulmonary coccidioidomycosis.

Conclusions

Though history and laboratory findings are supportive, definitive diagnosis still depends on growth in culture or endospores identified on histology. We suggest that orthopaedic surgeons and radiologists keep in mind that chronic fungal infections can mimic osseous neoplasm by imaging.

Keywords:
Coccidioidomycosis; Patella; Infection; Lytic lesion; Computed tomography; MRI