Prepubertal gynecomastia: a rare manifestation of myotonic dystrophy type 1 / Ginecomastia pré-púbere: uma manifestação rara da distrofia miotônica tipo 1

ABSTRACT Objective: To present a case of bilateral gynecomastia in a prepubertal boy with autism spectrum disorder, diagnosed with myotonic dystrophy type 1. Case description: A 12-year-old boy with autism spectrum disorder presented at a follow-up visit with bilateral breast growth. There was a family history of gynecomastia, cataracts at a young age, puberty delay, and myotonic dystrophy type 1. The physical examination showed that he had bilateral gynecomastia with external genitalia Tanner stage 1. Neurologic examination was regular, without demonstrable myotonia. The analytical study revealed increased estradiol levels and estradiol/testosterone ratio. After excluding endocrine diseases, the molecular study of the dystrophia myotonica protein kinase gene confirmed the diagnosis of myotonic dystrophy type 1. Comments: A diagnosis of prepubertal gynecomastia should include an investigation for possible underlying diseases. This case report highlights the importance of considering the diagnosis of myotonic dystrophy type 1 in the presence of endocrine and neurodevelopmental manifestations.

RESUMO Objetivo: Apresentar o caso de um adolescente pré-púbere com ginecomastia bilateral e transtorno do espectro autista, diagnosticado com distrofia miotônica tipo 1. Descrição do caso: Adolescente do sexo masculino de 12 anos, com transtorno do espectro autista, observado em consulta de seguimento por crescimento mamário bilateral. O paciente tinha antecedentes familiares de ginecomastia, catarata em idade jovem, atraso pubertário e distrofia miotônica tipo 1. À observação física, apresentava ginecomastia bilateral estádio 1 de Tanner. O exame neurológico era normal, sem miotonia aparente. O estudo analítico mostrou níveis elevados de estradiol e da relação estradiol/testosterona. Após exclusão de causas endócrinas, o estudo molecular do gene DMPK confirmou o diagnóstico de distrofia miotônica tipo 1. Comentários: Perante um quadro de ginecomastia pré-púbere, deve-se excluir doenças subjacentes. Este caso reforça a importância de considerar o diagnóstico de distrofia miotônica tipo 1 na presença de manifestações endócrinas e do neurodesenvolvimento.

Transient Complete Atrioventricular Block in a Preterm Neonate with Congenital Myotonic Dystrophy: Case Report

Congenital myotonic dystrophy (CMD) is an inherited neuromuscular disorder with cardiac rhythm abnormalities that may occur as a child grows. No report has described complete atrioventricular (AV) block detected in a neonate with CMD. We report a floppy infant of 31(+4) weeks gestation with complete AV block at birth, who was diagnosed with CMD by Southern analysis. She recovered from complete AV block 32 hr after temporary transcutaneous pacing was applied. To the best our knowledge, this is the first recorded case of a complete AV block accompanied by CMD during the neonatal period. When a newborn has a complete AV block, the physician should consider the possibility of the CMD and conduct a careful physical examination.