Isolated cryptococcal osteomyelitis of the ulna in an immunocompetent patient: A case report

Abstract

Background: Cryptococcal osteomyelitis is a bone infection caused by cryptococcus. As an opportunistic infection, bone cryptococcosis usually occurs in patients with immunodeficiency diseases or in those undergoing immunosuppressive therapy and often displays characteristics of disseminated disease. Isolated cryptococcal osteomyelitis is extremely unusual in immunocompetent person. The pathogenic fungus often invades vertebrae, femur, tibia, rib, clavicle, pelvis, and humerus, but the ulna is a rare target.

Case summary: A 79-year-old woman complaining of chronic pain, skin ulceration and a sinus on her right forearm was admitted, and soon after was diagnosed with cryptococcal osteomyelitis in the right ulna. Unexpectedly, she was also found to have apparently normal immunity. After treatment with antifungal therapy combined with surgery debridement, the patient's osteomyelitis healed with a satisfactory outcome.

Conclusion: Although rare, cryptococcal osteomyelitis should be considered in the differential diagnosis of osteolytic lesions even in immunocompetent patients, and good outcomes can be expected if early definitive diagnosis and etiological treatment are established.

Keywords: Case report; Cryptococcus neoformans; Immunocompetence; Isolated lesions; Osteomyelitis; Ulna.

Figure 1

Preoperative clinical photograph of wound ulceration 3 cm × 2 cm in size on the dorsal ulnar aspect of the mid-distal third of right forearm. The wound partially coated with purulent matter and communicated with the ulnar bone.

Figure 2

Preoperative X-ray. A: Anteroposterior film; B: Lateral film. A and B showed multiple irregular low-density osteolytic lesions (white arrows) with little periosteal reaction in the diaphyseal bone at the mid-distal shaft of the ulna, with a swollen soft tissue shadow, the internal fixation of the proximal ulna no loosening.

Figure 3

Preoperative computed tomography scan. A: Horizontal image; B: Coronal image; C: Sagittal image. Images showed the largest bone defect (white arrows) in the mid-distal portion of the right ulna, measuring 2.9 cm × 1.2 cm × 4.2 cm.

Figure 4

The wound was surgically debrided and irrigated, leaving a bony defect (white arrows) in the right ulna which was filled with amphotericin B-loaded cement.

Figure 5

Histopathological examination demonstrated chronic osteomyelitis characterized by granulation tissues with multinucleated giant cells (yellow arrow), and neutrophil infiltration (green arrows) (Hematoxylin-eosin stain 40 × 10).

Figure 6

Postoperative X ray. A: Anteroposterior film; B: Lateral film. A and B showed that the amphotericin B-loaded cement filled the defect area (white arrow) of the right ulna after surgical debridement.

Figure 7

The wound had healed well 3 mo after surgery.

Figure 8

X ray. A: Anteroposterior film; B: Lateral film. Three months after surgery showed that the osteolytic lesions (white arrows) had shrunk and blurred (except the bone cement filled lesion) in the right ulna.

Figure 9

X ray. A: Anteroposterior film; B: Lateral film. Ten months after surgery showed the osteolytic lesions had healed (except the bone cement filled lesion) in the right ulna.