Pycnodysostosis (PYCD) is a rare autosomal recessive skeletal dysplasia, due to a defect in the gene encoding cathepsin K, and characterized by short stature (SS), osteosclerosis, acro-osteolysis, skull deformities, and bone fragility. Although SS is characteristic in PYCD, GH deficiency has been reported only in some cases. We present two isolated cases, with typical clinical-radiological pictures. Case 1: a 9 year-old boy, offspring of consanguineous parents, presenting SS, osteosclerosis, bone fragility, bilateral ocular proptosis, frontal bossing, brachycephaly, wide cranial sutures, open fontanels, micrognathia, abnormal teeth, brachydactyly, dystrophic nails, and acro-osteolysis of the distal phalanges. Case 2: a 17 year-old boy, presenting SS, prominent nose, brachycephaly, plastibasia, separated cranial sutures, large fontanels, mandibular hypoplasia, abnormal teeth, diffuse osteosclerosis, brachydactyly, acro-osteolysis and increased cutaneous pleats in the hands. Both patients presented normal levels of TSH, free T4, gonadotropins and testosterone, and normal GH and cortisol responses to pharmacological stimuli. In conclusion, PYCD is a heterogeneous condition with variable clinical presentation. Thus, although not observed in these cases, but in light of previous descriptions, we consider important that patients with PYCD be routinely submitted to hormonal evaluation.
Pycnodysostosis; Skeletal dysplasia; Short stature; Cathepsin K; Growth hormone
