Cryptococcal osteomyelitis. Report of a case with aspiration biopsy of a humeral lesion with radiologic features of malignancy

BACKGROUND: Osteomyelitis due to Cryptococcus neoformans typically exhibits lytic lesions on radiographs. Extensive periosteal reaction is an uncommon feature. CASE: A 68-year-old man presented with pain and swelling in the left elbow. Radiologic studies exhibited a lytic humeral lesion with extensive periosteal reaction, interpreted as a malignant neoplasm. Fine needle aspiration biopsy (FNA) revealed abundant cryptococcal organisms. CONCLUSION: Cryptococcus is an uncommon cause of lytic osseous lesions that may mimic malignant neoplasms. Extensive periosteal reaction may support a radiologic diagnosis of primary osseous malignancy in rare cases. FNA with examination of Diff-Quik-stained slides may be employed for distinguishing cryptococcal osteomyelitis from malignant tumors and for prompt identification of the organisms.