Objectives: Although sarcopenia and osteoporosis are inter related conditions that are common with advancing age, few studies have explored relationships between muscle quality and bone mineral density (BMD). We investigated age and sex-specific paraspinal muscle fat infiltration (MFI), muscle cross-sectional area (CSA), and spine volumetric BMD (vBMD) in healthy Chinese adults. Methods: 605 healthy adults aged 20-59y (340 women, mean age 39.2y; 265 men, mean age 38.8y) had axial T2WI MRI imaging of the lumbar spine and CSA (cm2) and MFI (%) were measured in the psoas and multifidus and erector spinae (MF-ES) muscles (L3-L4). MFI measurements were calibrated against a region of interest in an adjacent area of subcutaneous pure fat. L2-L4 vBMD was measured by quantitative computed tomography. Age and sex-specific subgroups were compared using the Mann-Whitney test. Multiple regression was used to test independent associations of MFI and CSA with vBMD. Results: Females had lower CSA and higher MFI than males in both the psoas and MF-ES muscles (p < 0.001). In females and males, MF-ES MFI increased with age (p < 0.001) and in females age-related increases were observed for the psoas muscles (p < 0.05). Greater fat infiltration of the MS-ES muscle unit was associated with lower vBMD in both sexes (p < 0.001) but not with CSA. Following adjustment for demographic variables and CSA, MS-ES MFI remained predictive of vBMD (β = −0.408 to −0.157, p < 0.001). Conclusions: We have demonstrated that, independent of CSA and demographic variables, MFI of the MF-ES muscles is predictive of lower lumbar spine vBMD in both sexes. Advances in knowledge: This is the first study to demonstrate that, independent of muscle size and demographic variables, MFI of the paraspinal MF-ES muscles is predictive of lower lumbar spine vBMD in both sexes.

Peutz–Jeghers syndrome (PJS) is a rare genetic disorder characterized by multiple gastrointestinal polyps and mucocutaneous pigmentation. Abnormal pigmentation typically develops in infancy or childhood. As PJS-related facial pigmentation can lead to psychological burden due to its effects on esthetics, treatment is required. Herein, we report on the efficacy and safety of treatment of lip mucosal pigmentation using a Q-switched 755 nm Alexandrite Laser in children with PJS, aged 2–12 years of age. A topical anesthetic was used prior to the application of laser therapy. A treatment efficacy of 100% was achieved with one to three treatments, with an excellent outcome achieved in five cases (62.5%) and a good outcome in three (37.5%). Recurrent pigmentation was observed in one case over the 6-month follow-up period. There were no adverse effects, such as scarring or hyperpigmentation or hypopigmentation. The treatment did cause pain, apprehension, and crying in some children, requiring special attention. Although our sample size is small, our findings do provide support of the high efficacy and safety of the Q-switched 755 nm Alexandrite Laser for the treatment of lip mucosal pigmentation in children with PJS. Further studies are required to confirm these findings.

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