Lenz-Majewski hyperostotic dwarfism is a very rare syndrome caused by a de novo heterozygous mutation of phosphatidylserine synthase 1 (PTDSS1) gene (Sousa et al. 2013). It was first described by Braham in 1969 as the Camurati-Engelman syndrome but soon later became the Braham-Lenz syndrome until it was re-classified by Lenz and Majewski in 1974. Only thirteen reported cases are described in the Anglo-Saxon literature.

The most important feature is a disproportionately large head in relation to a reduced size trunk and limbs. Large fontanels and widely separated sutures that close lately in childhood are present. The skin is loose, wrinkled, and atrophic with prominent veins, especially in the scalp. The ears are large and floppy, and frequently associated are choanal atresia or stenosis, nasolacrimal duct obstruction, and, in boys, cryptorchidism and inguinal hernia. There is craniofacial dysmorphic evolution with age, leading to progressive macroglossia, prognathism, midface hypoplasia, and upper airway obstruction.

The disorder is also characterized by failure to thrive and severe mental retardation. This condition can be mistaken for craniometaphyseal and craniodiaphyseal dysplasias. However, the absence of cranial nerves impingement confirms the diagnosis. Enlarged ventricles and hydrocephalus have been described in some patients.

The skeletal alterations are striking with the following radiographic features:

• progressive sclerosis of the skull, facial bones, and vertebrae
• broad clavicles and ribs
• short or absent middle phalanges
• diaphyseal undermodeling and midshaft cortical thickening
• metaphyseal and epiphyseal hypostosis
• retarded skeletal maturation

Tooth enamel is also defective.