Fat embolism syndrome after minor trauma in an adolescent with Duchenne muscular dystrophy: a case report

Article information

Pediatr Emerg Med J. 2026;.pemj.2026.01697

Publication date (electronic) : 2026 July 6

doi : https://doi.org/10.22470/pemj.2026.01697

Seo Kyoung Chung¹, Wonjin Jang^,1,2, You Sun Kim^1,2, Bongjin Lee^1,2, June Dong Park^1,2

¹Department of Pediatrics, Seoul National University Hospital, Seoul, Republic of Korea

²Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea

Corresponding author: Wonjin Jang Department of Pediatrics, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea Tel: + 82-2-2072-3682; E-mail: jangchris@snu.ac.kr

Received 2026 May 21; Revised 2026 June 15; Accepted 2026 June 22.

Abstract

Introduction

Patients with Duchenne muscular dystrophy (DMD) are vulnerable to fractures after low-energy trauma because of progressive immobility, chronic corticosteroid exposure, and reduced bone mineral density (1,2). Fat embolism syndrome (FES) after minor trauma or occult fracture has been described in patients with DMD, but published studies remain limited and largely consist of case reports and small case series (3-5).

FES is uncommon in children and may not be included early in the differential diagnosis, even when elements of its classic triad, including respiratory failure, neurologic disturbance, and petechial rash, are present (6,7). Initial findings are instead interpreted as more common conditions that can affect patients with DMD, such as aspiration pneumonia, sepsis, or cardiomyopathy-related heart failure (8). We report a case of FES in an adolescent male with DMD after a minor fall from a wheelchair, in which the severity of respiratory failure and shock was inconsistent with the initial working diagnosis, and the recognition required repeated clinical assessment.

This case report was prepared in accordance with the principles of the Declaration of Helsinki. Written informed consent for publication of the case details and clinical images was obtained from the patient and his parents.

Case

A 17-year-old, 30 kg male with DMD presented to the emergency department at 6:00 a.m. with dyspnea, nausea, dizziness, and agitation. Four hours before the presentation, he had fallen from a wheelchair onto his left buttock, which was not witnessed. After the fall, he reported only mild lower-extremity pain and denied head injury. He had no preceding respiratory symptoms or other recent traumatic events.

He had been receiving chronic oral corticosteroid therapy with deflazacort (0.5 mg/kg/day) and calcium supplementation since he was 6 years old, and had been non-ambulatory since he was 13 years old. Baseline cognitive function was normal. Surveillance studies 4 months earlier showed borderline-normal systolic function without overt cardiomyopathy, with a left ventricular ejection fraction of 55%, normal pulmonary function, and osteoporosis of the spine and femur.

On arrival at the emergency department, the initial vital signs were as follows: blood pressure, 70/52 mmHg; heart rate, 147 beats/minute; respiratory rate, 18 breaths/minute; temperature, 36.9 °C; oxygen saturation, 82% on room air; and a Glasgow Coma Scale of 12 (eye-opening, 3; verbal response, 4; and motor response, 5). He was agitated and unable to cooperate fully with the neurological examination. Crackles were heard symmetrically at both lower lung fields without diminished breathing sounds. The only apparent traumatic findings were a small bruise and abrasion on the left knee.

Supplemental oxygen was administered by face mask at 10 L/minute, and diagnostic evaluation was initiated for hypoxemia, shock, altered mental status, and possible traumatic injury. Laboratory findings were as follows: platelets, 121  10³/L; d-dimer, 25.4 g/mL (reference value, 0.04–0.49); aspartate aminotransferase, 207 IU/L; alanine aminotransferase, 156 IU/L; C-reactive protein, 0.6 mg/dL; and procalcitonin, 1.12 ng/mL. Otherwise, laboratory findings were unremarkable. A chest radiograph showed bilateral lower-lung-field haziness without pneumothorax or hemothorax. Preliminary reading of the lower extremity radiographs reported no definite fracture. Brain computed tomography (CT) was normal. Chest CT showed multifocal centrilobular ground glass opacities without evidence of pulmonary thromboembolism. Bedside echocardiography showed no regional wall motion abnormality and an estimated ejection fraction of 52%. Aspiration pneumonia was initially considered because the patient presented with bilateral crackles, lower-lung-field haziness on the chest radiograph, and multifocal ground glass opacities on the CT. Empiric antibiotics were started for the presumed aspiration pneumonia, and norepinephrine was initiated for persistent shock.

However, oxygen demand increased and blood pressure progressively decreased over the following hours despite the initial treatment. By 3:00 p.m. on day 1, he underwent endotracheal intubation and transfer to the pediatric intensive care unit. Despite mechanical ventilation and escalating vasopressor support, he remained severely hypoxemic and hemodynamically unstable. The oxygenation index was 18 and the ratio of arterial oxygen partial pressure to the fractional inspired oxygen was 106, indicating a substantial oxygenation failure. Over the ensuing hours, endotracheal secretions became foamy and blood-tinged.

The severity of respiratory failure and the hemodynamic instability appeared disproportionate to aspiration pneumonia, particularly in view of the absence of reported vomiting or preceding respiratory symptoms, normal C-reactive protein concentration, progressive hemodynamic deterioration, foamy blood-tinged secretions, and preserved left ventricular function. Pulmonary hypertension or vascular dysfunction was therefore suspected. At 7:00 p.m., inhaled nitric oxide and inodilator therapy with dobutamine and milrinone were added, after which oxygenation and hemodynamics gradually improved.

The clinical course prompted reassessment for alternative causes of the deterioration. At 10:00 p.m., repeat physical examination identified petechial lesions on the anterior trunk that had not been recognized at initial assessment (Figure 1). At this point, FES was considered as a presumptive diagnosis based on the combination of recent minor trauma, DMD-associated osteoporosis, severe hypoxemia, altered mental status, and petechiae.

Figure 1.

Petechial rash scattered on the anterior trunk noted on a repeat physical examination. Published under the written consent of the patient’s legal guardian.

Given the presumptive diagnosis, fundoscopy was requested to evaluate for retinal manifestations of fat embolism. The fundoscopy performed at 10:00 a.m. on day 2 showed Purtscher flecken, supporting the diagnosis of FES (Figure 2). At 11:00 a.m., we obtained the formal radiology report on the initial chest CT, describing a diffuse alveolar hemorrhage compatible with FES, as well as a subtle cortical fracture of the right distal femur on the initial radiographs (Figure 3A, B). A follow-up echocardiography, obtained at 2:00 p.m. with additional imaging planes, showed interventricular septal flattening and tricuspid regurgitation, consistent with pulmonary hypertension. Brain magnetic resonance imaging performed at 4:00 p.m. demonstrated a starfield pattern of restricted diffusion, further supporting cerebral fat embolism (Figure 3C, D).

Figure 2.

Fundoscopy showing the bilateral Purtscher flecken, which appear as multiple peripapillary and perivascular white retinal patches.

Figure 3.

Findings of chest computed tomography (A), plain radiography of the right knee (B), and brain magnetic resonance imaging (C, diffusion-weighted; D, T2-weighted). The tomography shows bilateral multifocal ground glass opacities, suggesting diffuse alveolar hemorrhage compatible with fat embolism syndrome (A). The radiograph shows osteopenia and a subtle cortical fracture of the right distal femur (B). Diffusion-weighted imaging demonstrates a bilateral starfield pattern of punctate hyperintense lesions (C), with corresponding T2-weighted lesions (D). The arrows indicate the lesions of interest.

In this regard, the final diagnosis was made as FES following an occult distal femur fracture. The hemodynamic instability and pulmonary hypertension improved, and inotropes and inhaled nitric oxide were discontinued on day 3. The patient was extubated on day 5 and subsequently discharged on day 11 after clinical recovery (Figure 4).

Figure 4.

Timeline of presentation, reassessment, diagnostic confirmation, and recovery. FES: fat embolism syndrome, iNO: inhaled nitric oxide, MRI: magnetic resonance imaging, PICU: pediatric intensive care unit, OI: oxygenation index, P/F: ratio of PaO₂ to FiO₂, TR: tricuspid regurgitation.

Discussion

The pathophysiology of FES is generally explained by embolization and endothelial inflammation. Bone marrow injury allows fat droplets to enter disrupted venous sinusoids and embolize to the pulmonary circulation, producing microvascular obstruction, ventilation-perfusion mismatch, and acute pulmonary hypertension. Hydrolysis of fat into free fatty acids further contributes to endothelial injury, capillary leak, and diffuse alveolar hemorrhage, while systemic embolic and inflammatory effects account for neurologic and retinal manifestations (9,10).

Although FES is typically associated with long bone fracture after high-energy trauma, patients with DMD have a lower threshold for clinically meaningful marrow injury. Progressive loss of ambulation and chronic corticosteroid exposure reduce bone mineral density, predisposing the patients to low-energy, occult fractures (1,2). Hence, even a minor injury, such as a fall from a wheelchair, can initiate a multisystemic injury process disproportionate to the observed external injury (11).

FES is a diagnosis of exclusion, as no single test could sufficiently rule in or out the diagnosis (9). In the present case, the patient fulfilled all 3 major Gurd and Wilson criteria including respiratory insufficiency, cerebral involvement, and petechial rash (Appendix [https://doi.org/10.22470/pemj.2026.01697]) (7). Four minor criteria were also present, including tachycardia, retinal changes, thrombocytopenia, and decreased urine output during shock. The Schonfeld score was 14, exceeding the threshold of 5, generally used to support the diagnosis (9,12).

Although the patient exhibited most components of FES, the diagnosis was not reached initially. At first, the CT and radiograph were interpreted as aspiration pneumonia and no obvious fracture, respectively (Figure 3A, B). However, recognition of this mismatch between the clinical course and the presumptive diagnosis prompted reassessment and targeted evaluation, establishing the diagnosis of FES. Although FES has no specific antidotal therapy, diagnostic confirmation was important because it helped exclude alternative and potentially treatable causes of the deterioration, supported management directed toward pulmonary vascular dysfunction, and prevented continued anchoring on the insufficient presumptive diagnosis.

In DMD-associated FES, diagnostic clues may often be present but interpreted within more familiar diagnostic categories. Pediatric FES is rare, but its consideration is warranted in children or adolescents with neuromuscular diseases and bone fragility when hypoxemia or neurologic deterioration follows low-energy trauma, particularly when clinical severity is disproportionate to a presumptive diagnosis. The practical lesson for emergency and critical care physicians is not to screen every child or adolescent after minor trauma for FES, but to recognize that this disease entity exists and to reconsider it when the clinical trajectory is more severe than the initial diagnosis could explain.

Article information Continued