OMIM ID:
Organoid Nevus Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
The sebaceous nevi often involve the eyelids, cornea, and conjunctiva. Dermoids and lipodermoids are also seen. Iris and choroidal colobomas are often present. The sclerae may contain cartilage and bone which can be visible on CAT scans. Depending upon the structures involved, patients may have strabismus, nystagmus, ptosis, exposure keratitis, and nerve palsies.
Systemic Features
Phakomatous lesions on the skin seem to preferentially occur on the upper part of the body including the face, neck and scalp but they may occur anywhere on the body including the oral cavity. Initially they appear as papules but become verrucous around puberty. Malignant transformation is seen in 15-20 per cent of patients.
Mental retardation and seizures are often seen in the first year of life. Milestones achieved during that time are often lost subsequently. Generalized weakness, osteopenia, and intracranial aneurysms are features in some patients. Bone involvement may be highly asymmetrical.
Biopsies of conjunctival lesions show choristomas containing hyperplastic sebaceous and apocrine glands along with hair follicles.
Genetics
Inheritance
No clear genetic basis exists for this disease. However, several families with multigenerational involvement have been reported in an autosomal dominant pattern. It has been suggested that the disorder may result from a dominant lethal gene that allows some patients to survive by chance mosaicism.