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Título

Pompe Disease (PD) in a patient with acromegaly previously diagnosed as polymyositis - A case report

RESUMO

Case presentation: A 46-year-old male patient, sixth son of non-consanguineous parents and with no similar family history, was previously diagnosed with acromegaly (enlargement of nose, hands and ears, mandibular prognathism and deep voice) due to a pituitary adenoma. Six years ago he started to have proximal muscle weakness. Muscle biopsy revealed mild muscle atrophy with a lymphocyte infiltrate, suggestive of an inflammatory myopathy. He was diagnosed with polymyositis and treated with prednisone, with little response. One year later he was forwarded to a neurology outpatient clinic with progressive fatigue, difficulty standing up and low back pain. Symptoms have become worse over time. The last examination showed grade 4 muscle weakness globally and marked hypotrophy of proximal muscles, including pectorals, associated with a myopathic gait. Deep tendon reflexes were hypoactive globally. Plantar responses were indifferent. Cranial nerves, sphincter function and bulbar muscles were preserved. He had elevated creatine kinase (327 IU/L). A next-generation sequencing panel for neuromuscular disorders was performed and showed two GAA pathogenic variants (c.-32-13T>G - intronic; and Exon 18 deletion). Enzymatic testing for acid alpha-glucosidase was 0,64 (reference range - 4.57 ± 1.37 umol/L/h), which confirmed Pompe disease (PD). Discussion: PD is still underdiagnosed in Brazil and may affect people of all ages with varying degrees of severity, usually presenting as a limb-girdle myopathy, predominantly in lower limbs. Symptoms such as dysarthria, dysphagia, scoliosis, pain, fatigue and sphincter involvement can also be found. Mild PD is common in late-onset patients. Because of its similar presentation, PD can be mistaken for polymyositis, which also exhibits a progressive proximal weakness pattern. This patient had a biopsy reportedly compatible with polymyositis, but search for serum antibodies was negative and corticosteroid therapy didn’t show any improvement. In those situations, testing for genetic myopathies might reveal alternative diagnoses of potentially treatable conditions, such as PD. Final considerations: To the best of our knowledge, this is the first case of PD in a patient with a typical presentation of acromegaly. Here we also highlight the recognition of Pompe disease as an important differential diagnosis of polymyositis. This knowledge can reduce the delay in etiologic determination and might reveal potentially treatable conditions.

Palavras Chave

Pompe Disease. Polymyositis. Diagnosis.