Epidermal nevus syndromes encompass a wide variety of disorders. The specific symptoms present, severity and prognosis can vary greatly depending on the specific type of ENS and the presence and extent of associated extra-cutaneous symptoms. The onset and progression of these disorders varies greatly as well.
Epidermal nevi have also been classified as “hamartomas”, a rather vague and ambiguous term for benign tumor-like malformations that can affect any area of the body. “Hamartomas” are composed of mature cells and tissue normally found in the affected area. There are different types of epidermal nevi based upon their main component. Epidermal nevi are usually present at birth (congenital) and appear as a patch or plaque of overgrown skin. Epidermal nevi often occur on the trunk, limbs, face or scalp. Epidermal nevi can be striking and obvious in appearance or subtle and easy to miss.
Generally, epidermal nevi on the head and face are more likely to be associated with malformations of the brain, eyes and cranial bones. Epidermal nevi on the trunk are more likely to be associated with abnormal curvature of the spine, hip malformation and deformities of the arms and legs.
The lesions, apart from their appearance, usually do not cause additional symptoms. Individuals with a sebaceous nevus of the head may later develop intralesional tumors such as trichoblastoma or basal cell carcinoma. Recent research, however, suggests that this risk may be overstated in the medical literature. In fact, the risk of life-threatening malignant growth is virtually absent. Hence, there is no need to remove a sebaceous nevus for cancer prophylaxis (avoidance of malignant tumors).
This disorder is characterized by multiple sebaceous nevi and defects affecting the brain, eyes and bones. The skin lesion affecting individuals with Schimmelpenning syndrome is called sebaceous nevus because it predominantly affects the sebaceous glands (small oil-producing glands in the skin). Schimmelpenning syndrome is the most common type of ENS. The sebaceous nevus is present at birth (congenital), although it might not be identified until later during childhood, or even after puberty. The scalp and mid-facial area are most often affected. The arms, legs and trunk may also be affected. Sebaceous nevi are usually salmon or yellowed colored, hairless, smooth patches. Eventually (usually around puberty) they become more pronounced and may appear scaly, warty or thickened. When the scalp is involved, large Lesions may be present. These are usually hairless.
Sebaceous nevi often occur as isolated findings. However, when they occur with additional extra-cutaneous symptoms, the term Schimmelpenning syndrome is appropriate. In addition to sebaceous nevi, individuals with Schimmelpenning syndrome may have Neurological abnormalities including seizures, delays in attaining developmental milestones (developmental delays), intellectual impairment and malformations affecting certain structures of the brain.
Ocular abnormalities also occur in Schimmelpenning syndrome and include a partial absence of tissue (coloboma) from the colored portion of the eye (iris) or the membrane lining the back of the eyes (retina), clouding (opacity) of the cornea, crossed eyes (strabismus), defects of the optic nerve and scarring degeneration or detachment of the retina. Some individuals may have a benign, yellowish-white, fatty tumor on the outer portion of the eyeball (epibulbar lipodermoid).
Affected individuals also have skeletal malformations including abnormal curvature of the spine, dislocation of the hip, and deformities of the limbs. Craniofacial defects such as an unusually prominent forehead (frontal bossing) may also occur. Additional skeletal malformations may include bone cysts, underdevelopment of the pelvis and incomplete formation of the bony structures including the ankle, foot and bones of the spinal column (vertebrae).
Individuals with Schimmelpenning syndrome may also develop vitamin D-resistant rickets, a condition characterized by bowing deformities of the legs, Pain in the legs and progressive softening of the bone structure. In children, growth rates may be slow, ultimately resulting in short stature. Affected individuals may be prone to fractures.
In the past, the term “epidermal nevus syndrome” was used to describe Schimmelpenning syndrome. Unfortunately, some authors still use these terms interchangeably. Additional terms used to describe this disorder include Schimmelpenning-Feuerstein-Mims syndrome, linear sebaceous nevus sequence, sebaceous nevus syndrome and Jadassohn sebaceous nevus syndrome.
This type of ENS is characterized by the presence of a sebaceous nevus and a condition known as speckled lentiginous nevus of the papular type. (For a description of sebaceous nevus see Schimmelpenning syndrome above.) Speckled lentiginous nevus is characterized by large, light-brown discoloration of the skin, superimposed by multiple darkened (melanocytic) spots (papules). While sebaceous nevus is present at birth, the characteristic Papules of speckled lentiginous nevus may not develop until later in life, whereas the café-au-lait background macules showing a checkerboard arrangement tend likewise to be present in the newborn.
Individuals with phacomatosis pigmentokeratotica may also develop additional abnormalities, especially neurological and skeletal abnormalities. Neurological abnormalities include seizures, intellectual impairment, muscle weakness, Paralysis on one side of the body (hemiparesis), underdevelopment of one side of the boy (hemiatrophy), excessive Sweating (hyperhidrosis), and cutaneous dysesthesia, a condition in which touching the skin causing a feeling of unpleasantness.
Skeletal abnormalities may include abnormal side-to-side curvature of the spine (scoliosis) and vitamin D-resistant rickets, a condition characterized by bowing deformities of the legs, Pain in the legs and progressive softening of the bone structure. In children, growth rates may be slow, ultimately resulting in short stature. Affected individuals may be prone to fractures.
Additional findings that have been reported in this disorder include Hearing loss in one ear, crossed eyes (strabismus), droopy of the upper eyelid (ptosis) and narrowing of the aorta (aortic stenosis).
NEVUS COMEDONICUS SYNDROME
Nevus comedonicus is a skin lesion composed of closely-set, widened follicular openings that, in principle, belong to a hair follicle but in nevus comedonicus are plugged with keratin, a major structural protein found in the outer layer of skin as well as hair and nails. These Lesions are often found on the head, but can also occur on the trunk and limbs. These Lesions may be complicated by large cysts containing sebum (oil).
In nevus comedonicus syndrome, the characteristic skin lesion occurs with additional symptoms. These symptoms generally occur on the same side of the body (ipsilateral) as the skin lesion. Additional findings may include cataracts, webbing of the fingers or toes (syndactyly), abnormal fixation of the pinky so that it is bent toward the ring finger (clinodactyly), an extra thumb (preaxial polydactyly), abnormal curvature of the spine (scoliosis), and vertebral defects. Neurological abnormalities may also occur such as cognitive deficiencies, abnormal formation of the area of the brain that connects the two cerebral hemispheres (dysgenesis of the corpus callosum), and microcephaly, a condition that indicates that head circumference is smaller than would be expected for an infant’s age and gender.
ANGORA HAIR NEVUS SYNDROME (SCHAUDER SYNDROME)
This type of ENS is characterized by an epidermal nevus that is covered by long, soft white hairs. The lesion is arranged in a broad, band-like shape. Angora hair nevus syndrome may be associated with seizures, intellectual impairment, and Paralysis of one side of the body (hemiparesis). Distinctive facial features may also occur including abnormal prominence of the forehead (frontal bossing), malformed ears and an abnormally large tongue (macrostomia). Ocular abnormalities may also occur including cataracts, partial absence of tissue (coloboma) from the colored portion of the eye (iris), optic nerve defects and conditions that affect the structure or function of the pupils (ectopic pupils). Angora hair nevus syndrome is also known as Schauder syndrome.
BECKER NEVUS SYNDROME
A Becker nevus is characterized by one or more Lesions that usually form a checkerboard pattern. A Becker nevus is characterized by overactivity of hair follicles and pigment cells (melanocytes). Affected individuals have a large dark brown patch of skin that has often been reported to involve the shoulder, back or chest. However, this skin lesion can develop anywhere on the body. After puberty, a Becker nevus will darken and in males will show excessive hair growth. Some males with a Becker nevus may exhibit asymmetric growth of the beard.
Individuals with Becker nevus syndrome may exhibit underdevelopment of the breast on the same side of the body as the skin lesion (ipsilateral breast hypoplasia). This finding affects both males and females, but is more noticeable in females. Extra (supernumerary) nipples and abnormally Sparse hair under the armpit on the affected side of the body may also occur.
Individuals with Becker nevus syndrome have skeletal and muscular abnormalities including abnormal curvature of the spine (scoliosis), vertebral defects, fused ribs, uneven growth of the arms and legs, underdevelopment of the teeth and jaws (odontomaxillary hypoplasia) and a sunken chest or an abnormally prominent chest (pectus excavatum and pectus carinatum). Muscular abnormalities may include underdevelopment of the muscles of the shoulder girdle on the affected side of the body.
Becker nevus syndrome may also be known as pigmented hairy epidermal nevus syndrome.
The characteristic finding of Proteus syndrome is overgrowth of various tissues of the body. The cause of the disorder is unknown. Disproportionate, asymmetric overgrowth occurs in a mosaic pattern (i.e., a random “patchy” pattern of affected and unaffected areas). Affected individuals may experience a wide variety of complications that may include progressive skeletal malformations, benign and malignant tumors, malformations of blood vessels (vascular malformations), bullous pulmonary disease, and certain skin Lesions such as keratinocytic nevi. In some cases, life-threatening conditions relating to abnormal blood clotting may develop including deep vein thrombosis and pulmonary embolism.
A keratinocytic nevus is a linear skin lesion characterized by an overgrowth of keratinocytes, the predominant cell type in the epidermis. It affects approximately 50 percent of individuals with Proteus syndrome and is usually of a soft and velvety texture. Unlike other skin Lesions associated with Proteus syndrome, it does not become progressively larger.
Additional cutaneous findings associated with Proteus syndrome include telangiectatic nevi (flat, dark red areas of capillary malformation), underdeveloped areas of skin (dermal hypoplasia), benign growths that consist of masses of lymph vessels (lymphangiomas) and Lesions that arise from the deeper layers of skin (connective tissue nevi). Connective tissue nevi predominantly affect the palms and soles and cause the skin to become abnormally thickened and firm and the affected areas may develop grooves or furrows that resemble the fissures of the brain (cerebriform).
For more information on this disorder, choose “Proteus” as your search term in the Rare Disease Database.
TYPE 2 SEGMENTAL COWDEN DISEASE
Cowden disease is part of a group of disorders known as PTEN hamartoma syndromes, a spectrum of disorders caused by mutations of the PTEN gene. These disorders are characterized by multiple hamartomas that can affect various areas of the body. Type 2 segmental Cowden disease refers to a multisystem disorder caused by mutations of the PTEN gene that is also associated with a linear Cowden nevus, a type of keratinocytic nevus.
Type 2 segmental Cowden disease is similar to Proteus syndrome and some cases have been misdiagnosed as Proteus syndrome. However, there are several key differences in appearance. Unlike the keratinocytic nevus associated with Proteus syndrome, the skin lesion associated with type 2 segmental Cowden disease is thick with a surface that resembles that of the common wart (papillomatous). Moreover, type 2 segmental Cowden disease is not associated with connective tissue nevi of the palms and soles, but is associated with a kidney disorder known as focal segmental glomerulosclerosis (which does not occur in Proteus syndrome).
CHILD is an acronym for [c]ongenital [h]emidysplasia with [i]chthyosiform nevus and [l]imb [d]efects. The disorder almost exclusively affects women and is present at birth. Symptoms generally affect one side of the body (hemidysplasia); the right side is affected twice as often as the left. Skin abnormalities present as inflamed reddish patches that are covered by large, waxy, yellowish scales. A wide variety of additional findings may occur on the same side of the body as the skin Lesions including skeletal, neurological and visceral abnormalities.
Skeletal abnormalities may range from mild underdevelopment (hypoplasia) of bones of the hand or feet to complete absence of a limb. Additional skeletal malformations include cleft hand or foot, abnormal curvature of the spine (scoliosis), underdevelopment of half of the face (facial hemihypotrophy), and short stature. Some infants may have a condition called chondrodysplasia punctata that is visible upon x-rays. This condition is characterized by the formation of small, hardened spots of calcium on the growing portion or heads of the long bones (stippled epiphyses).
Neurological abnormalities include underdevelopment or absence of one of the two hemispheres of the brain, underdevelopment or absence of certain cranial nerves, Paralysis on one side of the body (hemiparesis), decreased sensation to touch or heat, and Hearing loss due to an impaired ability of the auditory nerves to transmit sensory input to the brain (sensorineural hearing loss).
Visceral abnormalities include cardiovascular defects, underdevelopment or absence of a kidney or unilateral underdevelopment of the lung.
For more information, choose “CHILD” as your search term in the Rare Disease Database.
This form of ENS is characterized by a keratinocytic epidermal nevus that is soft and velvety in texture. Neurological abnormalities including seizures, intellectual impairment, degeneration of brain cells (cortical atrophy) and underdevelopment of the area of the brain that connects the two cerebral hemispheres (corpus callosum) can also occur. Skeletal abnormalities have not been reported in this disorder. Garcia-Hafner-Happle syndrome has only been reported in a handful of cases. It is caused by mutations to the fibroblast growth factor receptor 3 (FGFR) gene and is also called FGFR3 epidermal nevus syndrome.
There are several additional disorders that are considered “in limbo”. These syndromes have only been described in a handful of individuals and the underlying molecular basis is unknown. Researchers have yet to determine whether they are distinct types of ENSs or variants of well-defined ENSs.
These disorders are sometimes referred to as less well-defined types of ENSs. They include:
CLOVE syndrome – an acronym for [c]ongenital [l]ipomatous [o]vergrowth, [v]ascular malformations, and [e]pidermal nevus. CLOVE syndrome is extremely similar to Proteus syndrome and many individuals with this disorder were originally diagnosed with Proteus syndrome. According to the medical literature, the key difference is that overgrowth of toes in CLOVE syndrome is “ballooning”, nonprogressive and proportionate while with Proteus syndrome such overgrowth is distorted, progressive and disproportionate. Some researchers believe that CLOVE syndrome may represent a variant of Proteus syndrome and not a distinct disorder. This question will be answered once the underlying molecular basis of these two disorders is discovered.
Nevus trichilemmocysticus syndrome – characterized by multiple cysts, which are derived from the root sheath of the hair follicle (trichilemmal cysts), that occur along with bone lesions.
Didymosis aplasticosebacea – the coexistence of a nevus sebaceous along with aplasia cutis congenita, a condition characterized by a lack of skin and hair in certain areas (localized), most often on the scalp. These Lesions are usually localized and found close together.
SCALP syndrome – an acronym for [s]ebaceous nevus, [c]entral nervous system malformations, [a]plasia cutis congenital, [l]imbal [d]ermoid and [p]igmented nevus.
Gobello syndrome – reported in one individual in 2000, Gobello syndrome was associated with an organoid nevus with a velvety surface as well as excessive hairiness (hypertrichosis) and rough, elevated Papules (follicular hyperkeratosis). Skeletal abnormalities were also present.
Baefverstedt syndrome – Reported in one individual in 1941, Baefverstedt syndrome was associated with abnormal horny growths on the skin in a linear pattern. Neurological symptoms such as Intellectual disability and Seizures were also noted. The horny growths developed on the face, neck and underarms and became quite prominent.