Muscle MRI in neutral lipid storage disease (NLSD)

We present the muscle imaging data of 12 patients from the Italian Registry of Neutral Lipid Storage Disease (NLSD): ten patients presenting NLSD with myopathy (NLSD-M) carrying recessive mutations in PNPLA2 gene, and two patients presenting the NLSD with ichthyosis (NLSD-I) mutated in ABHD5 gene. In NLSD-M gluteus minimus, semimembranosus, soleus andgastrocnemius medialis in the lower limbs and infraspinatus, trapezius, deltoid and paraspinous muscles in the upper limbs were the most affected muscles. Gracilis, sartorius, subscapularis, pectoralis, triceps brachii and sternocleidomastoideus were spared. Muscle involvement was not homogenous and characteristic “patchy” replacement was observed in at least one muscle in all the patients. Half of the patients showed one or more STIR positive muscles. In both NLSD-I cases muscle involvement was not observed by T1-TSE sequences but one of them showed positive STIR images in more than one muscle in the leg. Our data provide evidence that muscle imaging can identify characteristic alterations in NLSD-M, characterized by a specific pattern of muscle involvement with “patchy” areas of muscle sparing/replacement. Larger cohorts are needed to assess if a distinct pattern of muscle involvement exists also for NLSD-I.