Dados do Trabalho

Título

Late onset asymmetric myopathy: a case of neutral lipid storage disease

RESUMO

Presentation:
We present a male patient, 42 years-old, active smoker, without comorbidities. At 38 years of age, he developed an asymmetrical proximal weakness in the upper limbs. Over the next 04 years, there was slowly progressive worsening of weakness in the upper limbs and evolution to the lower limbs. On neurological examination, the patient had asymmetric tetraparesis, with proximal predominance in the upper limbs and distal predominance in the lower limbs, with grade 2 strength at arm abduction bilaterally, grade 2 for forearm flexion and 4 for extension bilaterally, but more prominent on the right side. Dorsiflexion of the right feet was grade 2, and 4 on the left. Selective atrophy of the biceps brachii muscle with sparing of the triceps brachii were remarkable. Investigation showed serum creatine kinase of 3.033. Electromyography had a pattern of asymmetric myopathy with proximal predominance, nerve conduction study was normal. Biceps brachii muscle biopsy showed muscle fibers with intracytoplasmic vacuoles and intracytoplasmic masses, alterations suggestive of metabolic myopathy. A genetic panel was performed and showed a homozygous likely pathogenic variant in PNPLA2, ( c.421-1G>A) consistent with neutral lipid storage disease with myopathy (NLSDM).

Discussion:
Neutral lipid storage disease with myopathy (NLSDM) is a metabolic myopathy, characterized by the presence of triglyceride-containing cytoplasmic droplets in leukocytes and in other tissues, including bone marrow, skin, and muscle. NLSDM is an autosomal recessive muscle disorder caused by mutations in the PNPLA2 gene. Usually presents with juvenile-onset (after the first decade) of slowly progressive proximal muscle weakness with increased serum creatine kinase; distal muscle weakness may also occur. Multisystem involvement with cardiomyopathy, dyslipidemia, hepatomegaly, and/or diabetes is present in 20 percent or more of cases. Our patient had a late onset of weakness and absence of multisystem involvement, with neurological examination and complementary work up compatible with metabolic myopathy due to lipid accumulation.

Final Comments:
Until the present date of submission of this report, no registry was found for the genetic variant c.421-1G>A on PNPLA2, making this a probably novel pathogenic variant. Our case study highlights the importance of considering neutral lipid storage disease for patients with late onset asymmetric myopathies.

Palavras Chave

NLSDM; PNPLA2; metabolic myopathy