Abstract
Introduction
Duchenne muscular dystrophy (DMD) is a severe X-linked recessive genetic disease that affects approximately 1 in 5,050 males at birth. Although most cases are hereditary and diagnosed in males, de novo mutations and symptomatic female carriers have been described. Mutations in the DMD gene result in reduced or absent dystrophin protein. Dystrophin acts as a molecular shock absorber, protecting the sarcolemma during routine muscle contraction. Due to a lack of dystrophin, tears accumulate in the sarcolemma, leading to muscle fiber necrosis. Early symptoms begin during childhood, presenting initially with muscle weakness and difficulty ambulating. This then progresses to involve other organ systems, leading to gastroparesis, urinary dysfunction, respiratory failure/ventilation, dilated cardiomyopathy, and death. Currently, the life expectancy for someone diagnosed with DMD is between 20-40 years, with a median of 28.1 years if born after 1990. We report a case of a 27-year-old male previously diagnosed with DMD presenting to the emergency department for a painful, erythematous skin rash on his distal right leg. We will also discuss the role of imaging studies in the management of DMD and radiological findings often seen in those diagnosed with DMD.
Case Info
A 27-year-old male with a past medical history of DMD requiring a wheelchair and 24/7 assistance with activities of daily living, dilated cardiomyopathy, restrictive lung disease, and osteoporosis presents to the ED with a painful, erythematous, warm, and edematous skin rash overlying the right distal tibia/fibula. These symptoms began 2 days ago, causing him to initially present to another hospital, where he was prescribed cephalexin and doxycycline before being discharged. Despite adhering to his antibiotics, his symptoms have continued to worsen.
Vital signs are 98.1 F, heart rate 108, respiratory rate 18, blood pressure 117/60, and SpO2 98%. WBC count, lactate, and procalcitonin are within normal limits. Metabolic panel demonstrates mild hyperglycemia, and hepatic function panels show mild ALT elevation but are otherwise unremarkable. At this moment, he does not meet SIRS criteria. Differential diagnosis initially includes cellulitis, DVT, and peripheral artery disease. An X-ray of the tibia, duplex vascular ultrasound, two chest X-rays, and a lower extremity CT with contrast were ordered during his hospital visit.
Disc Clinical
Several radiologic findings are commonly seen in those diagnosed with DMD. These include muscle with progressive fatty replacement and atrophy, calf pseudohypertrophy, spine/skeletal findings like lordosis, scoliosis, and osteoporosis, reduced lung volumes, and atelectasis. The patient in this case report demonstrates many of these findings. These include a low lung volume with atelectasis, severe diffuse fatty infiltration into the gastrocnemius, and skeletal changes including osteoporosis. Additionally, edema of the right lower extremity with stranding on the dorsum of the foot is identified.
Conclusion
The patient was diagnosed with cellulitis and discharged home on Linezolid after notable improvement in his cellulitis symptoms while on IV antibiotics. Although radiographic studies are not used for diagnosing DMD, several imaging modalities are used to aid with supportive measures and monitor disease progression.