Opsismodysplasia is a type of skeletal dysplasia (a bone disease that interferes with bone development) first described by Zonana and associates in 1977, and designated under its current name by Maroteaux (1984). Derived from the Greek opsismos ("late"), the name "opsismodysplasia" describes a delay in bone maturation. In addition to this delay, the disorder is characterized by micromelia (short or undersized bones), particularly of the hands and feet, delay of ossification (bone cell formation), platyspondyly (flattened vertebrae), irregular metaphyses, an array of facial aberrations and respiratory distress related to chronic infection. Opsismodysplasia is congenital, being apparent at birth. It has a variable mortality, with some affected individuals living to adulthood. The disorder is rare, with an incidence of less than 1 per 1,000,000 worldwide. It is inherited in an autosomal recessive pattern, which means the defective (mutated) gene that causes the disorder is located on an autosome, and the disorder occurs when two copies of this defective gene are inherited. No specific gene has been found to be associated with the disorder. It is similar to spondylometaphyseal dysplasia, Sedaghatian type. Presentation
Opsismodysplasia can be characterized by a delay in bone maturation, which refers to "bone aging", an expected sequence of developmental changes in the skeleton corresponding to the chronological age of a person. Factors such as gender and ethnicity also play a role in bone age assessment. The only indicator of physical development that can be applied from birth through mature adulthood is bone age.
Eruptive vellus hair cysts (or EVHC) are small lesions that occur most often in the chest wall, abdomen and extremities, often with a crusted surface. : 680  EVHC may occur randomly, or it can be inherited as an autosomal dominant trait. The condition affects males and females equally, and sporadic cases usually appear at 4–18 years of age. The cysts appear similar clinically to steatocystoma multiplex, as well as acneiform eruptions and milia. Therapeutic techniques that are safe and effective are rare, with incision and drainage being the primary form of treatment when sporadic regression does not occur. It was first described in 1977. Signs/symptoms
Cause
Diagnosis
Histopathology is the basis of diagnosis. Stratified-squamous epithelium with a granular layer that surrounding a cystic space filled with laminated keratin and a variable number of vellus hair cysts is seen to be present. It can be difficult to distinguish from other skin conditions, including molluscum contagiosum and acne vulgaris but can be corroborated with histopathology. Associations
It can be associated with Steatocystoma multiplex. Treatment
The primary indication for treatment is cosmesis. Retinoids, surgery, and lasers are used as treatment modalities. See also
Steatocystoma simplex
Milia
List of cutaneous conditions

References
Further reading
Torchia, Daniele; Vega, Janelle; Schachner, Lawrence A. (1 February 2012). "Eruptive Vellus Hair Cysts". American Journal of Clinical Dermatology. 13 (1): 19–28. doi:10.2165/11589050-000000000-00000. PMID 21958358.