PMC6558532_01
PMC6558532_02
The child, 12 years old, was thin and weak and presented flat feet and
short fingers with weak extensor indicis and carpi ulnaris muscles.
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He was not able to stand from the floor and was unable to lift legs from the bed. He appeared thin, frail and weak (Figure 1A-C).
Muscle biopsy of patient 2 shows diffuse fibre atrophy and some central
nuclei with haematoxylin-eosin stain (A). Acid ATPase (pH 4) shows 92%
type 1 fibre predominance (B). Nicotinamide adenine dinucleotide
tetrazolium reductase (NADH-TR) showed abnormal nuclei and mitochondrial
accumulation (C), periodic acid-Schiff (PAS) stain shows deposit of
glycogen localized in some fibres (D). Ultrastructural analysis shows
atrophic fibres with myelinoid body in subsarcolemmal position (E),
cytoplasmatic body with mitochondrial alterations and vacuoles in nuclei
(F). Abnormal dense nuclei with central vacuoles can be seen in (F,
G).
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In the child muscle biopsy, morphologic findings by haematoxylin-eosin (HE) staining showed prominent fibre atrophy with acid ATPase stain (pH 4) with a 92% type 1 fibre predominance (Figure 2A and B) was observed. NADH-TR showed the abnormal presence of mitochondrial rims and periodic acid-Schiff (PAS) reaction detected focal glycogen accumulation in some fibres (Figure 2C and D). Ultrastructural analysis showed abnormal mitochondrial accumulation, myelinoid bodies and occasional cytoplasmic bodies; several abnormal nuclei had a fenestrated appearance (Figure 2E-G).
Evaluation of muscle magnetic resonance imaging (MRI) in lower limbs in
patients 1 and 2 according to the Mercuri score. (A) Slight atrophy was
found in both legs and thighs of the female patient (mother of patient
2). Vastus lateralis, medialis and intermedius presented a 4 Mercuri
score; semitendinous and semimembranous muscles were spared with Mercuri
1 score. (B) Advanced atrophy was present, in posterior compartment
where soleus and gastrocnemius muscles were completely substituted with
fatty infiltration. (C) Muscles of patient 1 were characterized by
hypotrophy in the anterior thigh compartment. (D) Leg muscle mass was
less compromised.
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Muscle MRI of patient 1 revealed marked atrophy, fatty tissue replacement in the pelvic girdle and anterior thigh muscles, especially in vastus lateralis, vastus medialis and intermedius, whereas in posterior thigh semitendinous and semimembranous muscles were relatively spared (Figure 3A). Posterior leg muscles were characterized by marked atrophy, in particular, soleus and gastrocnemius muscles were completely replaced by fatty infiltration (Figure 3B).