Aspergillus granulosus femoral osteomyelitis in a cardiac transplant patient: first reported case and literature review

Abstract

Aspergillus osteomyelitis is a rare complication of extrapulmonary invasive aspergillosis, which usually presents as spondylodiscitis. The clinical picture is usually paucisymptomatic and of long evolution, which leads to diagnostic difficulties, especially in immunosuppressed patients presenting a delayed systemic host response. We report a case of femoral osteomyelitis caused by Aspergillus granulosus in a heart transplant recipient successfully treated with a combined surgical and antifungal approach. A 65-year-old heart transplant male presented with left knee pain lasting 3 months. X-ray and magnetic resonance imaging identified a lesion with aggressive characteristics at the distal third of the left femur, due to which the patient underwent excisional surgery. Aspergillus granulosus was cultured from the removed material and antifungal treatment with oral isavuconazole was started. Chest imaging excluded pulmonary aspergillosis, while the positron emission tomography/computed tomography (PET/CT) identified a remnant of a prosthetic vascular graft sewn to the proximal third of the right axillary artery, through which a catheter-based micro-axial left ventricular assist device was implanted previously as bridge to transplant therapy. The patient presented a rapid clinical improvement with complete functional recovery following the surgical treatment and the antifungal therapy and finally underwent surgical removal of the residual vascular graft. This is the first reported episode of long bone osteomyelitis due to A. granulosus that occurred in a heart transplant recipient without pulmonary infection and was successfully treated with isavuconazole. The PET/CT was useful in supporting the diagnostic process and follow-up. Cryptic fungal species can cause invasive infections, particularly in immunocompromised patients. Molecular methods are crucial in fungal identification.

Keywords: Aspergillus granulosus; case report; heart transplantation; invasive aspergillosis; invasive fungal infection; osteomyelitis; solid organ transplantation.

Figure 1.

Clinical evolution. Timeline of the evolution of the case depicting the main events concerning the episode described, including onset of symptoms, hospital admission, diagnosis and management.

Figure 2.

(a) Anterolateral X-ray of the left femur and the knee showing an osteolytic lesion of the distal metaphysis of the femur. (b) CT scan of both femurs and knees showing an osteolytic lesion of the distal metaphysis of the left femur. Arrows indicate the site of the lesion. CT, computed tomography.

Figure 3.

(a) Culture sample of the excised femoral lesion. On the left, white colonies on chocolate agar media. On the right, cinnamon–brown colonies on PDA medium. (b) Lactophenol cotton blue preparation of culture sample of the excised femur lesion. At the top, relatively sparse conidiophores are seen with poorly defined phialides (20×). At the bottom, globose to elongated Hülle cells are seen in clusters (40×). PDA, potato dextrose agar.

Figure 4.

(a) PET/CT of both femurs and knees after the surgical excision showing a nonspecific metabolic lesion in the left distal femur, with peripheral hypermetabolism and adjacent soft tissue, compatible with known fungal infection. (b) Chest PET/CT showing a focal uptake in the right retropectoral region, in the path of the axillary artery and vein. (c) CT angiography showing the remnant of the prosthetic graft sewn to the proximal third of the right axillary artery, located superficially to the pectoralis minor and in the interval between the sternocostal and clavicular heads of the pectoralis major (black arrow). CT, computed tomography; PET, positron emission tomography.

Figure 5.

(a) Remnant of the prosthetic vascular graft sewn to the right axillary artery. (b) Thrombotic material found within the prosthetic vascular graft.