OVERVIEW
Lipoid protein deposition disorder, also known as Urbach-Wiethe disease and cutaneous mucosal hyaline protein degeneration, is a rare hereditary disease. It occurs in infants and is characterized by amorphous eosinophilic hyaline deposits in the skin, mucous membranes, or viscera, and by thickening of the eyelids, yellow verrucous plaques on the elbows and knees, and hoarseness.
Etiology
Genetic studies have revealed that the disease is inherited in an autosomal recessive manner. The exact cause of the metabolic disorder is unknown.
Symptoms
1. Primary type (non-photoreceptor type)
This type occurs in infants, and scarring can form from minor inflammatory skin injuries. Hoarseness can occur at birth or shortly after birth and becomes a major symptom of infancy. Yellowish-white infiltrated patches with a hard texture are seen on the pharynx, tongue and lip mucosa. Extensive yellow infiltrates with irregular surfaces are also seen on the soft palate, tonsillar arches, uvula, and sublingual areas, and the tonsils are covered with a hard white layer. Laryngeal involvement is often severe, with nodules visible on the epiglottis and vocal cords. The tongue is enlarged and hard to touch as “wood-like”, which limits the range of motion and cannot be extended beyond the lips, and may even cause dysphagia. When the infiltration compresses the parotid duct, it may cause recurrent parotid gland swelling and pain. Occasionally the vaginal mucosa and labia are involved.
Skin changes become progressively more prominent in early childhood, with the development of small yellowish-brown nodules on the face, alopecia with scalp involvement, and rashes occurring on the upper and lower lid margins or eyelids as candida papules or thickening of the eyelids with loss of eyelashes. Lesions located on the elbows and knees behave like xanthomas. If skin trauma occurs, the skin at the site of trauma gradually appears to be infiltrated and darkens to brown color. The surface is clearly keratinized and wart-like, which occurs on the backs of the hands and other places much like common warts.
The disease is often associated with dental abnormalities and certain systemic diseases such as diabetes mellitus and intracranial epilepsy or psychiatric symptoms due to lipoprotein deposits. Calcification may occur and may be detected on cranial radiographs.
2. Secondary type (photoreceptor type)
This type is essentially an erythropoietic protoporphyria. It is sensitive to light and therefore presents with skin changes characterized by inflammation and secondary changes in exposed areas.
Examination
Calcification occurs may be detected as foci of calcification on cranial radiographs. Histopathology: Hyperkeratosis is seen in the epidermis with irregular thickening or atrophy of the stratum spinosum. Characteristic changes are seen in the dermis, which is markedly thickened, with vasodilatation, thickened vessel walls, and extracellular eosinophilic hyaline material in the superficial dermis. Calcification may be detected on cranial radiographs as foci of calcification.
Diagnosis
The general diagnosis is not difficult based on onset in infancy with hoarseness, tongue stiffness and thickening, and xanthomatous skin lesions. Pathologic examination is helpful in confirming the diagnosis.
Treatment
There is no specific treatment. Primary cases develop progressively and naturally settle in adulthood. Laryngeal involvement in childhood can sometimes lead to respiratory distress, and in a few severe cases tracheotomy is required. In secondary photoreceptor patients, symptoms often improve gradually after avoiding sun exposure.