Sternal wound complications following cardiac surgery are a significant source of morbidity and are most often attributed to deep sternal wound infections caused by common bacterial pathogens. However, a subset of non-healing, culture-negative wounds may harbor atypical organisms, such as fungi, which can be overlooked owing to their subtle clinical presentation. Fungal osteitis, particularly that caused by Aspergillus species, is an uncommon but serious condition that may not be recognized in its early stages. Delayed diagnosis can lead to prolonged wound deterioration, repeated surgical interventions, and the development of complex chest wall defects that complicate definitive reconstruction.

Identifying fungal involvement is particularly challenging because routine cultures may remain negative for extended periods, and local wound signs are often nonspecific. In such cases, clinical suspicion, targeted tissue biopsy, and histopathologic confirmation are essential. Management typically requires aggressive surgical debridement combined with long-term systemic antifungal therapy. Additionally, reconstruction must address both structural stability and thorough obliteration of dead space.

Here, we present a case of a patient with a persistent, culture-negative, post-sternotomy chronic wound following off-pump coronary artery bypass (OPCAB) grafting, ultimately diagnosed as Aspergillus fumigatus osteitis. The patient was successfully treated with serial debridement and free latissimus dorsi musculocutaneous flap coverage. This report highlights the diagnostic complexity and reconstructive considerations in the management of rare fungal chest wall infections.

According to the policies of our research institution, Institutional Review Board (IRB) approval is not required for case reports involving a single individual who cannot be identified. Therefore, IRB approval was waived for this case report. Written informed consent was obtained from the patient.

A 66-year-old man with a history of diabetes mellitus, unstable angina, and two-vessel coronary artery disease underwent OPCAB grafting using the left internal thoracic artery as a conduit. The immediate postoperative course was uneventful, and the patient was discharged in stable condition. The healed sternotomy wound remained stable during the first three postoperative months, but subsequently the patient developed new wound drainage and dehiscence. Despite multiple rounds of empirical antibiotic therapy and repeated debridement, the wound did not improve significantly. Serial deep wound cultures, blood tests, and inflammatory markers (including C-reactive protein and white blood cell count) remained nonspecific. Magnetic resonance imaging revealed ill-defined T2-hyperintense signals and minimal soft-tissue edema around the lower costosternal junctions, without marrow replacement or cortical disruption suggestive of osteomyelitis.

The patient ultimately underwent 15 serial debridement procedures. Initially, the thoracic surgery team performed nine sessions of debridement and attempted closure, with no procedures involving the cartilage or bone. Thereafter the patient was referred to our plastic and reconstructive surgery department, and a combined approach involving thoracic and plastic surgery was adopted for the remaining six debridement sessions. During these combined procedures, necrotic cartilage and devitalized tissue were identified around the costosternal junctions, and additional whitish discharge was drained from the deep spaces beneath the free-floating ribs. Earlier cultures derived from swabs or superficial tissues around the drainage tract were negative, and the diagnosis became clear only when tissues from the infected cartilage and adjacent deep structures were cultured; these tissue samples obtained during surgery yielded A. fumigatus, and histopathologic examination confirmed fungal osteitis with invasion of the costal cartilage. Intravenous voriconazole was administered.

Negative-pressure wound therapy (NPWT), first initiated when the patient developed wound problems, was subsequently applied repeatedly along with serial debridement over the following months. The patient was referred to our department about 5.5 months after the onset of wound dehiscence, corresponding to 8 months after the initial surgery. After referral, NPWT was continued for an additional 3.5 months. This prolonged NPWT resulted in persistent contraction of the skin and soft tissues, which consequently rendered primary and local flap closure not feasible. A narrow, elongated dead space persisted along the bilateral rib cartilage and bony debridement sites, while the wound base did not communicate with the pleural or peritoneal cavities (Fig. 1). Given these circumstances, definitive reconstruction was planned. During surgical debridement, transection of the right internal thoracic artery at the level of the 6th rib was confirmed, rendering an ipsilateral pedicled vertical rectus abdominis myocutaneous (VRAM) flap unavailable as a reconstructive option. The left pedicled VRAM flap was also not feasible because the left internal thoracic artery had been used as the graft conduit during the initial OPCAB procedure. Therefore, a free latissimus dorsi musculocutaneous flap was harvested and transferred to the anterior chest with microvascular anastomosis to the right internal thoracic artery and vein in the third intercostal space (Figs. 2-4). The flap provided durable soft-tissue coverage and effectively obliterated the residual dead space.

The patient recovered without complications. The flap survived completely, with no evidence of infection. Long-term oral antifungal therapy was maintained for 6 months postoperatively. At the 4-month follow-up, the patient showed no signs of recurrent infection or structural instability. The flap appeared clinically stable, with durable coverage of the anterior chest wall (Fig. 5).

Fungal osteomyelitis or osteochondritis involving the sternum is an exceedingly rare complication following cardiac surgery, particularly in immunocompetent patients [1]. In most cases, post-sternotomy wound complications are associated with bacterial deep sternal wound infections, primarily involving Staphylococcus aureus or coagulase-negative staphylococci [2]. However, Aspergillus species—most commonly A. fumigatus—have been reported in a limited number of cases, often presenting with an indolent clinical course and nonspecific signs that lead to delays in diagnosis and treatment.

In the present case, the patient exhibited persistent wound discharge without overt signs of systemic infection. Serial cultures remained negative for several weeks, which is not uncommon in fungal infections because of the limited sensitivity of conventional culture methods. This finding highlights the importance of maintaining clinical suspicion in patients with non-healing sternal wounds, particularly when empirical antibacterial therapy fails. Tissue biopsy for histopathologic examination and fungal culture remains the gold standard for definitive diagnosis [3].

In addition to these diagnostic challenges, this case demonstrates several features that distinguish it from previously reported instances of post-sternotomy fungal osteitis. First, despite substantial costal cartilage involvement confirmed intraoperatively, the patient exhibited no radiologic evidence of osteomyelitis, highlighting a radiologic–clinical discrepancy that is rarely demonstrated in the literature. Second, the patient experienced an unusually prolonged culture-negative course, with fungal growth identified only after multiple sessions of debridement, underscoring the limited sensitivity of conventional cultures and the importance of early deep-tissue sampling in non-healing wounds.

Surgical debridement plays a central role in managing fungal osteitis, as antifungal therapy alone is typically insufficient owing to poor penetration into necrotic bone and cartilage [4]. In our case, serial debridement resulted in exposure of the costal cartilage and creation of a sizable anterior chest wall defect. The right internal thoracic artery was transected at the level of the sixth rib during previous procedures, ruling out the use of a pedicled rectus abdominis musculocutaneous flap—a commonly favored option in sternal reconstruction.

The management of fungal osteitis requires a combined medical and surgical approach, with surgical debridement serving as the foundation for effective infection control. Because antifungal agents have limited penetration into necrotic bone and devitalized cartilage, debridement must extend to healthy, bleeding tissue margins even when there is no definitive radiologic or clinical evidence of mediastinitis. In such cases, the principles guiding surgical management include the removal of all necrotic costal cartilage, excision of devitalized soft tissue, and repeated intraoperative reassessment during staged procedures to ensure complete source control. These steps are essential to creating a clean, well-vascularized bed that can support definitive reconstruction and reduce the risk of persistent or recurrent infection. The present case followed these principles, with serial debridement performed until no residual necrosis was identified and the wound demonstrated stable granulation tissue suitable for flap coverage.

Post-sternotomy defects can be managed with several reconstructive options, each suited to different clinical situations. The pectoralis major flap is a commonly used local option, but its reach may be limited in long or bilateral lower sternal defects. Pedicled flaps, such as the VRAM flap, can provide reliable volume, although they are not feasible when the internal thoracic vessels are disrupted, as in our case. The omental flap offers excellent vascularity but requires abdominal entry, which carries additional morbidity risks. Free flaps, including the latissimus dorsi and anterolateral thigh flaps, are useful for extensive or irregular defects because they allow greater flexibility in positioning and pedicle selection. Among these, the latissimus dorsi free flap provides a suitable amount of pliable muscle with low donor-site morbidity, making it an appropriate choice for the narrow, bilateral cartilage defect encountered in this patient [2,5].

Prolonged systemic antifungal therapy is essential in the management of Aspergillus osteomyelitis. Voriconazole remains the first-line treatment because of its proven efficacy and bone penetration profile [3]. In this case, the patient received intravenous voriconazole for 4 weeks, followed by an additional 6-month course of oral voriconazole after definitive reconstruction. At the 4-month follow-up, no signs of recurrence were observed, underscoring the importance of combined surgical and medical management.

This case highlights several key clinical considerations: (1) the need to consider fungal organisms in culture-negative, non-healing post-sternotomy wounds; (2) diagnostic utility of deep tissue sampling and histologic analysis; and (3) reconstructive value of free latissimus dorsi musculocutaneous flap transfer when pedicled options are not viable because of prior graft harvest or vessel injury. Awareness of these principles is essential for the timely diagnosis and successful management of this rare but severe complication.