Pycnodysostosis: An Early Case Report With Emphasis On The Radiographic Findings

摘要

Pyknodysostosis (PKND) is a rare sclerosing bone disorder, characterized with generalized diffuse osteosclerosis. The head is usually large with fronto-parietal bossing and open fontanelles, hypoplastic malar and maxillary bones.We report a case of PKND in a 4-year-old male child, first referred for evaluation with a possible diagnosis of osteopetrosis, because of his multiples members and clavicles fractures. We describe the clinical findings, dentomaxillofacial radiologic exams and differential diagnosis from osteopetrosis. Introduction Pycnodisostosis (PKND) is an esqueletal autossomal recessive disorder. Patients with PKND usually have normal intelligence, sexual development and life span1. Other clinical features are skull deformities, an obtuse gonial angle, hypoplastic paranasal sinus, shortened terminal phalanges and a history of multiple fractures of the members and clavicles2. Oral manifestations include anterior crossbite, increase incidence of dental caries, hipoplastic maxilla2. . Radiographic findings include bone density increase, persistent fontalelles and failure of closure of the cranial sutures1,2. This syndrome has been seen in many races and nationalities, including black, Arab and caucasians3. The medical literature reports some cases in pediatric patients. We report here a case in a 4-year-old male child, the youngest reported in the literature to our knowledge. Case Report The patient is a four years-old male of mixed Portuguese, Afro-Brazilian and Amerindian ancestry. He is the second child of a consanguineous couple (first-cousins) who had a previous miscarriage. He also has a healthy maternal half-sister. Family history is otherwise unremarkable. Pregnancy was complicated by amniorrexis in the second trimester. Delivery was at term in good conditions, birth weigh 3,700 g, height 50 cm and Apgar scores 9/10.At the clinical evaluation his weight was12 kg and stature 90 cm (both below the 3rd percentile) and a Occipitofrontal head circumference (OFC) of 48.5 cm (3rd percentile). He was also noted to present prominent calvaria, open fontanelles, small faces with micrognathia and brachydactyly of fingers with shortening of the distal phalanges. Clinical oral exam showed multiple acute dental cavities, associated with malpositioned teeth and anterior crossbite. Neuropsychomotor development was normal. At age four, both fontanelles remain open. The patient also presented with multiple fractures of the members and clavicles being referred for evaluation due to a possible diagnosis of osteopetrosis.The radiological evaluation consisted in a panoramic (fig 1), postero-anterior skull x-ray (fig 2) and hand radiograph (fig 3). These exams revealed generalized sclerosis of the skeleton, including skull, being more pronounced in the periorbital region (“harlequin appearance” or “raccoon mask” sign), wormian bones, open fontanelles and cranial sutures; absence of facial sinuses, and obtuse mandible angle and clubbing of the terminal phalanges.