Gait disturbance and lower limb pain in a patient with PIK3CA -related disorder

Evolution over Time of Leg Length Discrepancy in Patients with Syndromic and Isolated Lateralized Overgrowth

OBJECTIVE

To provide information on evolution over time of leg length discrepancy in patients with syndromic and isolated lateralized overgrowth.

STUDY DESIGN

This retrospective study investigates leg length discrepancy longitudinally in 105 patients with lateralized overgrowth either isolated (n = 37) or associated with Beckwith-Wiedemann spectrum (n = 56) or PIK3CA-related overgrowth spectrum (n = 12). Discrepancy was measured by standard methods and categorized as minor, mild, severe, and critical, based on the thresholds of 1, 2 and 5, respectively.

RESULTS

The period of observation from diagnosis was 1.7 ± 2.6 to 9.0 ± 6.0 years. Leg length discrepancy was 11.0 ± 7.2 mm at diagnosis and 17.1 ± 14.4 mm at last visit. Both final leg length discrepancy and change over time were correlated with discrepancy at diagnosis (r² = 0.45, P < .001 and r² = 0.05, P = .019, respectively). Among minor leg length discrepancy at diagnosis, 47.5% remained minor, 40.0% become mild, and 12.5% severe. Among patients with discrepancy classified as severe at diagnosis, 84.6% remained severe and 15.4% evolved to critical. The isolated lateralized overgrowth group showed a milder evolution over time compared with Beckwith-Wiedemann spectrum and PIK3CA-related overgrowth spectrum groups. Among patients with Beckwith-Wiedemann, those with paternal chromosome 11 uniparental disomy had more severe leg length discrepancy at diagnosis and evolution over time.

CONCLUSIONS

Leg length discrepancy associated with isolated or syndromic lateralized overgrowth tends to worsen with growth and correlates with discrepancy at first observation. Among the genotypic groups, isolated lateralized overgrowth tends to have a milder evolution, whereas Beckwith-Wiedemann spectrum predisposes to a more severe outcome, especially if associated with paternal chromosome 11 uniparental disomy genotype.

Lipoblastoma phenotype contains a somatic PIK3CA mutation

Lipoblastoma typically occurs in childhood and is associated with rearrangements of the PLAG1 gene. We present a patient with an isolated mass thought to be a lipoblastoma clinically, radiographically, and histologically. The lesion was diagnosed as a PIK3CA-adipose lesion after the tissue was negative for PLAG1 rearrangement and contained a somatic PIK3CA mutation (H1047R). Although PIK3CA variants are associated with PROS (PIK3CA-related overgrowth spectrum), this report illustrates a non-syndromic, lipoblastoma phenotype caused by a PIK3CA mutation.