Peutz-Jeghers syndrome with early onset of pre-adolescent gynecomastia: a predigree case report and clinical and molecular genetic analysis.

This study reports a case of Peutz-Jeghers syndrome with early onset of gynecomastia, and discusses its clinical characteristics and genetic changes in a family. The clinical characteristics of a child diagnosed with Peutz-Jeghers syndrome in our hospital and his parents were summarized, and related genes were detected in the child and his parents. Furthermore, the therapeutic effect of letrozole was also observed. A five-year-and-three-month-old male patient visited a doctor due to "progressive painless enlargements at bilateral breast for more than two years". The mother of the patient had breast hyperplasia and ovarian cysts, had no hematemesis and hematochezia history, and had two 1-mm pigmented spots on the palm side of the left thumb. The father of the patient revealed no abnormalities. In the child, luteinizing hormone (LH) release peak induced by luteinizing hormone releasing hormone (LHRH) excitation testing was 0.29 U/l, and follicle stimulating hormone (FSH) peak was 0.41 U/l. Karyotype: 46, XY. Gene sequencing revealed a mutation c.658C>T in the serine threonine kinase 11 (STK11) gene in the child and this mother, while the child's father was normal. After one year of oral administration of letrozole, the boy's breasts reduced to stage B2, bone age was 10 years and eight months old, and ΔBA/ΔCA ratio was <1. The patient had early onset of pre-adolescent gynecomastia, had no obvious gastrointestinal symptoms, presented with a few pigmented spots in the skin mucosa, and was diagnosed with Peutz-Jeghers syndrome by genetic testing. Letrozole treatment can effectively control the development of breast and progression of bone age.