High-density areas on muscle CT in childhood-onset Pompe disease are caused by excess calcium accumulation

We report two patients with childhood-onset Pompe disease showing striking changes with high-density areas on skeletal muscle CT, not seen in adult- or infantile-onset forms of this disease. While the anterior compartment of the thigh muscles was less affected in the adult-onset form, the rectus femoris and tibial muscles were preferentially involved from the early stage in the childhood-onset form of Pompe disease. The high-density areas became increasingly diffuse with disease progression, producing a marbled pattern and ultimately resulting in homogeneous high density and muscle atrophy. Muscle biopsy specimens from the high-density areas showed striking vacuolar changes with many dense globular bodies in lysosomes. High calcium signals were identified by X-ray microanalysis using energy-dispersive X-ray spectroscopy in these areas. Excess calcium accumulation in the vacuoles was also confirmed with the glyoxal-bis(2-hydroxyanil) (GBHA) staining. The high density on CT was slightly reduced together with clinical improvement after enzyme replacement therapy in patient 2. Our data demonstrate that in childhood-onset Pompe disease, high-density areas on skeletal muscle CT images are due to the accumulation of calcium in dense globular bodies formed by a chronic degenerative process affecting autophagic vacuoles.