Additional types of nevi do not involve disorders of pigmentation or melanocytes. These additional nevi represent hamartomatous proliferations of the epithelium, connective tissue, and vascular malformations.

Phakomatosis pigmentovascularis is subdivided into five types:

- Type 1 PWS + epidermal nevus

- Type 2 (most common): PWS + dermal melanocytosis +/- nevus anemicus

- Type 3: PWS + nevus spilus +/- nevus anemicus

- Type 4: PWS + nevus spilus + dermal melanocytosis +/- nevus anemicus

- Type 5: CMTC (Cutis marmorata telangiectatica congenita) + dermal melanocytosis

They all can contain capillary malformation. Type 2 is the most common and can be associated with granular cell tumor. Some further subdivide each type into categories A & B; with A representing oculocutaneous involvement and subtype B representing extra oculocutaneous involvement. Others have proposed fewer subtypes but currently this rare entity is mostly taught as having five subtypes currently.

Hypermelanotic nevi must be differentiated from other types of pigmented skin lesions, including:

- Lentigo simplex

- Solar lentigo

- Café au lait macule

- Ink-spot lentigo

- Mucosal melanotic macule

- Mongolian spot (dermal melanocytosis)

Phakomatosis pigmentovascularis is a rare neurocutanous condition where there is coexistence of a capillary malformation (port-wine stain) with various melanocytic lesions, including dermal melanocytosis (Mongolian spots), nevus spilus, and nevus of Ota.

Pigmented hairy epidermal nevus syndrome is a cutaneous condition characterized by a Becker nevus, ipsilateral hypoplasia of the breast, and skeletal defects such as scoliosis.

Since the original identification of Schimmelpenning syndrome, the number of findings has expanded to the point that the syndrome is associated with a considerable constellation of abnormalities. The abnormalities may occur in a variety of combinations, and need not include all three aspects of the classic triad of sebaceous nevus, seizures and mental retardation. In 1998, a literature review by van de Warrenburg et al. found:

- seizures in 67% of cases

- mental retardation in 61% of cases

- ophthalmological abnormalities in 59% of cases

- involvement of other organ systems in 61% of cases

- structural abnormality of cerebrum or cranium in 72% of cases

The major neurological abnormalities include mental retardation to varying extent, seizures, and hemiparesis. Seizures, when present, typically begin during the first year of life. The most common structural central nervous system abnormalities in Schimmelpenning syndrome are hemimegalencephaly and ipselateral gyral malformations.

The major ocular abnormalities are colobomas and choristomas.

Skeletal abnormalities may include dental irregularities, scoliosis, vitamin D-resistant rickets and hypophosphatemia. Cardiovascular abnormalities include ventricular septal defect and co-arctation of the aorta; urinary system issues include horseshoe kidney and duplicated urinary collection system.

Phakomatosis pigmentokeratotica is a rare neurocutanous condition characterized by the combination of an organoid sebaceous nevus and speckled lentiginous nevus. It is an unusual variant of epidermal naevus syndrome. It was first described by Happle "et al". It is often associated with neurological or skeletal anomalies such as hemiatrophy, dysaesthesia and hyperhidrosis in a segmental pattern, mild mental retardation, seizures, deafness, ptosis and strabismus.

Schimmelpenning syndrome is a neurocutaneous condition characterized by one or more sebaceous nevi, usually appearing on the face or scalp, associated with anomalies of the central nervous system, ocular system, skeletal system, cardiovascular system, and genitourinary system.

Synonyms include: "Linear nevus sebaceous syndrome (LNSS)", "Schimmelpenning-Feuerstein-Mims syndrome", "Feuerstein-Mims syndrome", "sebaceous nevus syndrome", "Solomon syndrome", and "Jadassohn's nevus phakomatosis". "Nevus" is sometimes spelled "naevus" and "sebaceous" may also be spelled "sebaceus". "Epidermal nevus syndrome" is sometimes used as a synonym, but more often as a broader term referring to Schimmelpenning syndrome in addition to nevus comedonicus syndrome, CHILD syndrome, Becker's nevus syndrome, and phakomatosis pigmentokeratotica.

The classic Schimmelpenning syndrome diagnosis comprises a triad of sebaceous nevi, seizures, and mental retardation. The condition was first reported by Gustav Schimmelpenning in 1957 and independently reported by Feuerstein and Mims in 1962.

Nevus psiloliparus is a cutaneous condition, a rare scalp anomaly characterized by a variable degree of alopecia and an excessive amount of adipose tissue.

It is the main hallmark of encephalocraniocutaneous lipomatosis (ECCL), otherwise known as Haberland syndrome.

Reticular pigmented anomaly of the flexures (also known as "dark dot disease", and "Dowling–Degos' disease") is a fibrous anomaly of the flexures or bending parts of the axillae, neck and inframammary/sternal areas. It is an autosomal-dominant pigmentary disorder that may appear in adolescence or adulthood. This condition is due to mutations in structural/desmosomal proteins found within stratified squamous epithelium.

Dark dot disease is associated with "KRT5".

The several components or degrees of development range from an ear tag, preauricular appendage, preauricular tag, or accessory tragus, to supernumerary ears or polyotia. It is a relatively common congenital anomaly of the first branchial arch or second branchial arches. Other anomalies may be present concurrently, including cleft palate, cleft lip, or mandibular hypoplasia. There is a known association with Goldenhar syndrome (oculo-auriculo-vertebral syndrome) and with Wildervanck syndrome. There may also be an association with congenital cartilaginous rest of the neck.

The general presentation is of a skin-covered nodule, papule, or nodule of the skin surface, usually immediately anterior to the auricle. However, it may be anywhere within the periauricular tissues. Bilateral presentation can be seen.

A seborrheic keratosis, also known as seborrheic verruca, basal cell papilloma, or a senile wart, is a non-cancerous (benign) skin tumour that originates from cells in the outer layer of the skin (keratinocytes). Like liver spots, seborrheic keratoses are seen more often as people age.

The tumours (also called lesions) appear in various colours, from light tan to black. They are round or oval, feel flat or slightly elevated, like the scab from a healing wound, and range in size from very small to more than across. They can often come in association with other skin conditions, including basal cell carcinoma. Sometimes seborrheic keratosis and basal cell carcinoma occur at the same location, and sometimes seborrheic keratosis progresses to basal cell carcinoma. At clinical examination the differential diagnosis include warts and melanoma. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts", because they resemble warts, but strictly speaking the term "warts" refers to lesions that are caused by human papillomavirus.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

Linear verrucous epidermal nevus (also known as a "Linear epidermal nevus," and "Verrucous epidermal nevus") is a skin lesion characterized by a verrucous skin-colored, dirty-gray or brown papule. Generally, multiple papules present simultaneously, and coalesce to form a serpiginous plaque. When this nevus covers a diffuse or extensive portion of the body's surface area, it may be referred to as a systematized epidermal nevus, when it involved only one-half of the body it is called a nevus unius lateris.

Red endemic skin as well as spongy and desquamating (peeling) skin are consistent with this syndrome.

Pregnancies that have a foetus affected with this syndrome are complicated because of polyhydramnion. Complications arise because of opaque amnionic fluid resulting from the shedding of skin. As a result, ultrasounds are difficult to conduct. Triggered by the harsh environment in the uterus, delivery results around 30– 34 weeks of gestation (pregnancy) and the baby is born in prematurely.

Seborrheic keratoses may be divided into the following types:

- Common seborrheic keratosis (basal cell papilloma, solid seborrheic keratosis)

- Reticulated seborrheic keratosis (adenoid seborrheic keratosis)

- Stucco keratosis (digitate seborrheic keratosis, hyperkeratotic seborrheic keratosis, serrated seborrheic keratosis, verrucous seborrheic keratosis) -- Often are light brown to off-white. Pinpoint to a few millimeters in size. Often found on the distal tibia, ankle, and foot.

- Clonal seborrheic keratosis

- Irritated seborrheic keratosis (inflamed seborrheic keratosis)

- Seborrheic keratosis with squamous atypia

- Melanoacanthoma (pigmented seborrheic keratosis)

- Dermatosis papulosa nigra—Commonly found among adult dark-skinned individuals, presents on the face as small benign papules from a pinpoint to a few millimeters in size.

- Inverted follicular keratosis

Also see:

- The sign of Leser-Trélat

In HWS the hair is coarse and sparse, eyelashes are sparse or absent, nails may be absent or malformed, and teeth may be small and malformed. There may be fewer than normal sweat glands and they may produce little sweat, a condition known generally as hypohidrosis. Chronic inflammatory dermatitis of the scalp is a common symptom.

Two features differentiate HWS from other ectodermal displasias. First, the syndrome is associated with cleft palate, and, less often, cleft lip. Second, the edges of the upper and lower eyelid grow bands of fibrous tissue, often causing them to be fused together. This condition in the eyelids is called "ankyloblepharon filiforme adnatum".

In dentistry, anodontia, also called anodontia vera, is a rare genetic disorder characterized by the congenital absence of all primary or permanent teeth. It is associated with the group of skin and nerve syndromes called the ectodermal dysplasias. Anodontia is usually part of a syndrome and seldom occurs as an isolated entity.

Congenital absence of permanent teeth can present as hypodontia, usually missing 1 or 2 permanent teeth, or oligodontia that is the congenital absence of 6 or more teeth. Congenital absence of all wisdom teeth, or third molars, is relatively common. Anodontia is the congenital absence of teeth and can occur in some or all teeth (partial anodontia or hypodontia), involve two dentitions or only teeth of the permanent dentition (Dorland's 1998). Approximately 1% of the population suffers from oligodontia. Many denominations are attributed to this anomaly: partial anodontia, hypodontia, oligodontia, the congenital absence, anodontia, bilateral aplasia. Anodontia being the term used in controlled vocabulary Medical Subject Headings (MeSH) from MEDLINE which was developed by the United States National Library of Medicine. The congenital absence of at least one permanent tooth is the most common dental anomaly and may contribute to masticator dysfunction, speech impairment, aesthetic problems, and malocclusion (Shapiro and Farrington 1983). Absence of lateral incisors represents a major stereotype. Individuals with this condition are perceived as socially most aggressive compared with people without anodontia (Shaw 1981).

Florid cutaneous papillomatosis (also known as the Schwartz-Burgess syndrome) is an obligate paraneoplastic syndrome.

FCP begins as the sudden onset of numerous cutaneous papillomas that are clinically indistinguishable from viral warts. The papillomas range from 1 to 3 mm in diameter may spread to involve the entire body, including the face. Pruritus, which may sometimes precede the onset of FCP, is evident in the affected regions in about half of patients. Evaluation of a skin biopsy clearly distinguishes FCP from viral warts.

FCP is associated with underlying cancer of the breast, bladder, ovary, uterus, prostate, and lung. Other associated underlying malignancies include squamous cell carcinomas and lymphomas such as non-Hodgkin's lymphoma.

FCP is sometimes seen together with other signs of internal cancer, especially malignant acanthosis nigricans, tripe palms, Leser–Trélat sign, and hypertrichosis lanuginosa acquisita. FCP tends to improve in association with surgical or chemotherapeutic therapy of the underlying internal cancer. A recurrence or exacerbation of FCP may be linked with tumor regrowth or metastatic spread.

Warty dyskeratoma, also known as an Isolated dyskeratosis follicularis, is a benign epidermal proliferation with distinctive histologic findings that may mimic invasive squamous cell carcinoma and commonly manifests as an umbilicated (Having a central mark or depression resembling a navel) lesion with a keratotic plug, WD have some histopathologic similarities to viral warts but it's not caused by HPV and the majority of these lesions display overall histopathologic features consistent with a follicular adnexal neoplasm. usually limited to the head, neck, scalp or face and vulva. Lesions are generally and sporadic and may be associated with a follicular unit. Oral involvement, particularly the hard palate, and genital involvement have been reported. it can also be thought of as one of the manifestations of focal acantholytic dyskeratosis, an epidermal reaction pattern that can be seen in several disorders, including Darier's disease and Grover's disease. But the main Difference between Darier disease and Warty dyskeratoma, is that Darier disease inherited dermatosis (autosomal dominant) consisting of multiple keratotic papules on the face, trunk, and extremities, while WD occurs as an isolated, noninherited, single keratotic nodule mainly confined to the head and neck as mentioned earlier.

Adnexal and skin appendage neoplasms is a group of tumors which develop in the adnexal skin structures such as the sweat and sebaceous glands. An example is the hidrocystoma.

A stucco keratosis is a common benign skin condition characterized by a lesion with a dull or lackluster surface, and with church-spire-like projections of epidermal cells around collagen seen histologically. Stucco keratoses are often light brown to off-white, and are no larger than a few millimeters in diameter. They are often found on the distal tibia, ankle, and foot.

Other names for a stucco keratosis are "digitate seborrheic keratosis," "dyperkeratotic seborrheic keratosis," "deratosis alba," "serrated seborrheic keratosis," and "verrucous seborrheic keratosis".

Steatocystoma multiplex, also known as epidermal polycystic disease and sebocystomatosis, is a benign, autosomal dominant congenital condition resulting in multiple cysts on a person's body. Steatocystoma simplex is the solitary counterpart to steatocystoma multiplex.