People with visible marks generally feel fine (physically) and can act normally, but when it is mentioned, they may become withdrawn and self-conscious. Some children may have low self-esteem due to the condition.

CMTC is an uncommon, sporadic congenital vascular malformation characterized by a generalized or localized reticulated cutaneous vascular network.

Cutaneous lesions described in patients with CMTC include nevus flammeus, hemangioma, nevus anemicus, café-au-lait spots, melanocytic nevus, aplasia cutis and acral cyanosis.

It has a marbled bluish to deep-purple appearance. The dark skin lesions often show a palpable loss of dermal substance. The reticulated mottling frequently appears more prominent in a cold environment (physiologic cutis marmorata), but tends not to disappear with warming. Hence, the erythema may be worsened by cooling, physical activity, or crying.

CMTC frequently involves the extremities, with the lower extremities involved most commonly, followed by the upper extremities, and then the trunk and face. The lower extremities often show atrophy and seldom show hypertrophy resulting in limb circumference discrepancy.

When located on the trunk, the lesions of CMTC tend to show mosaic distribution in streaks with a sharp midline demarcation seen across the abdomen. The lesions are primarily localized, but can be segmental or generalized, often unilateral in appearance. Diffuse involvement of the skin is usually not observed.

Although its course is variable, the majority of lesions in mild cases fade by adolescence. Ulceration and secondary infection are complications in severe cases and can be fatal if present in the neonatal period.

Hyperkeratotic cutaneous capillary-venous malformation is a cutaneous condition characterized also by inherited cerebral capillary malformations.

Presentation includes telangiectasia, acanthosis, and hyperkeratosis.

Presentation can be solitary or systemic.

Pyogenic granuloma, also known as lobular capillary hemangioma, is a small benign vascular tumor that primarily involves the skin (88.2%) and mucous membranes. Pyogenic granuloma appears as a red macule that grows rapidly, turns into a papule and eventually becomes pedunculated, being attached to a narrow stalk. The average diameter of these lesions is 6.5 mm. Although these lesions are small, they are often complicated by bleeding, crusting and ulceration. Microscopically, pyogenic granulomas are characterized by vascular amidst granulation tissue and chronic inflammatory infiltrate.

Pyogenic granulomas are rarely congenital. It commonly develops in infants: 42.1% develops within the first 5 years of life. This vascular tumor is twice as common in males as in females and 25% of lesions seem to be associated with trauma, an underlying cutaneous condition, pregnancy, hormonal alterations and medications. Pyogenic granulomas can also arise within a capillary malformation. Of all pyogenic granulomas, 62% is distributed on the head or neck, occurring mainly on the cheek and in the oral cavity. Lesions on the face may cause visible deformity.

Numerous treament methods have been described for pyogenic granuloma. Lesions involving the reticular dermis, may be out of the reach of pulsed-dye laser, cautery or shave excision and therefore have a recurrence rate of 43.5%. Definitive management requires full-thickness skin excision. Other options are currettage or laser therapy. Furthermore, thorough currettage and cauterization are often used for small lesions and full-thickness excision for larger lesion.

In some instances nodular angiokeratomas can produce necrotic tissue and valleys that can harbor fungal, bacterial and viral infections. Infections can include staphylococcus. If the lesion becomes painful, begins draining fluids or pus, or begins to smell, consult a physician. In these instance a doctor may recommend excision and grafting.

Vascular malformation is a collective term for different disorders of the vasculature (errors in vascular development). It can be a disorder of the capillaries, arteries, veins and lymphatic vessels or a disorder of a combination of these (lesions are named based on the primary vessel that is malformed). A vascular malformation consists of a cluster of deformed vessels, due to an error in vascular development (dysmorphogenesis). However, endothelial turnover is stable in these defects. Congenital vascular malformations are always already present at birth, although they are not always visible. In contrast to vascular tumors, vascular malformations do not have a growth phase, nor an involution phase. Vascular malformations tend to grow proportionately with the child. Vascular malformations never regress, but persist throughout life.

Vascular malformations can be divided into slow-flow, fast-flow and complex-combined types.

During the first few weeks after birth, when the lesions are not very reticulated, CMTC may look very similar to vascular lesions such as port-wine stains. However, during follow-up, CMTC lesions become characteristic in their appearance. They must be differentiated from other causes of persistent reticulated vascular lesions, such as those in the following table:

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.

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.

Hemihyperplasia–multiple lipomatosis syndrome is a cutaneous condition characterized by multiple lipomas in association with asymmetric (but non-progressive and non-distorting) overgrowth, cutaneous capillary malformations, and thickened plantar skin with prominent creases.

Stork bites occur in a significant number of newborns, with estimates ranging from to ; they are reported more frequently for white babies than for infants of other races. They result from a dilation of capillaries in the skin, and may become darker when the child cries or strains.

The birthmarks, which are pinkish and irregularly shaped, occur most frequently on the nape of the neck; however, they are also common on the forehead, eyelids and upper lip. A baby may be born with a stork bite, or the birthmark may appear in the first months of life. They may also be found occasionally on other parts of the body. The skin is not thickened and feels no different from anywhere else on the body; the only difference is in appearance.

Naevus flammeus nuchae, often called stork bite or nevus simplex, is a congenital capillary malformation present in newborns. It is a common type of birthmark in a newborn and is usually temporary.

Neurocutaneous melanosis is associated with the presence of either giant congenital melanocytic nevi or non-giant nevi of the skin. It is estimated that neurocutaneous melanosis is present in 2% to 45% of patients with giant congenital melanocytic nevi. Patients with non-giant congenital melanocytic nevi seem to have a much lower, but undefined risk. Of these patients, only a small number are symptomatic, usually displaying symptoms before the age of 2.

These symptoms are the result of melanocytic lesions being present in the leptomeninges of the central nervous system.

Symptoms can include:

- Papilledema

- Cranial palsies

- Headache

- Vomiting

- Seizures

Others symptoms may also exist that are related to an increase in intracranial pressure. These symptoms seem to be present regardless of the malignancy of the melanin deposits within the central nervous system.

Approximately 10% of patient with neurocutaneous melanosis also present the Dandy–Walker syndrome and associated Dandy-Walker malformation. This malformation involves an enlargement of the posterior fossae and fourth ventricle along with agenesis of the cerebellar vermis. The abnormalities of the leptomeninges during fetal development due to neurocutaneous melanosis may be the cause of this increased incidence of the Dandy-Walker malformation. The development of hydrocephalus is the most common symptom associated with a combination of neurocutaneous melanosis and a Dandy-Walker malformation, occurring in about two out of three patients.

Syringofibroadenoma (also known as "acrosyringeal nevus of Weedon and Lewis") is a cutaneous condition characterized by a hyperkeratotic nodule or plaque involving the extremities.

It is considered of eccrine origin.

Porokeratosis may be divided into the following clinical types:

- "Plaque-type porokeratosis" (also known as "Classic porokeratosis" and "Porokeratosis of Mibelli") is characterized by skin lesions that start as small, brownish papules that slowly enlarge to form irregular, annular, hyperkeratotic or verrucous plaques. Sometimes they may show gross overgrowth and even horn-like structures may develop. Skin malignancy, although rare, is reported from all types of porokeratosis. Squamous cell carcinomata have been reported to develop in Mibelli's type porokeratosis over partianal areas involving anal mucosa. This was the first report mentioning mucosal malignancy in any form of porokeratosis.

- "Disseminated superficial porokeratosis" is a more generalized processes and involves mainly the extremities in a bilateral, symmetric fashion. In about 50% of cases, skin lesions only develop in sun-exposed areas, and this is referred to as "disseminated superficial actinic porokeratosis"

- "Porokeratosis palmaris et plantaris disseminata" is characterized by skin lesions that are superficial, small, relatively uniform, and demarcated by a distinct peripheral ridge of no more than 1mm in height.

- "Linear porokeratosis" is characterized clinically skin lesions are identical to those of classic porokeratosis, including lichenoid papules, annular lesions, hyperkeratotic plaques with central atrophy, and the characteristic peripheral ridge.

- "Punctate porokeratosis" is a skin condition associated with either classic porokeratosis or linear porokeratosis types of porokeratosis, and is characterized by multiple, minute, and discrete punctate, hyperkeratotic, seed-like skin lesions surrounded by a thin, raised margin on the palms and soles.

- "Porokeratosis plantaris discreta" is a skin condition that occurs in adults, with a 4:1 female preponderance, characterized by a sharply marginated, rubbery, wide-based papules. It is also known as "Steinberg's lesion". It was characterized in 1970.

Acral fibrokeratoma (also known as an "Acquired digital fibrokeratoma," and "Acquired periungual fibrokeratoma") is a skin lesion characterized by a pinkish, hyperkeratotic, hornlike projection occurring on a finger, toe, or palm.

Livedo reticularis is a common skin finding consisting of a mottled reticulated vascular pattern that appears as a lace-like purplish discoloration of the skin. The discoloration is caused by swelling of the venules owing to obstruction of capillaries by small blood clots. The blood clots in the small blood vessels can be a secondary effect of a condition that increases a person's risk of forming blood clots, including a wide array of pathological and nonpathological conditions . Examples include hyperlipidemia, microvascular hematological or anemia states, nutritional deficiencies, hyper- and autoimmune diseases, and drugs/toxins.

The condition may be normal or related to more severe underlying pathology. Its differential diagnosis is broadly divided into possible blood diseases, autoimmune (rheumatologic) diseases, cardiovascular diseases, cancers, and endocrine disorders. It can usually (in 80% of cases) be diagnosed by biopsy.

It may be aggravated by exposure to cold, and occurs most often in the lower extremities.

The condition's name derives from the Latin "livere" meaning bluish and "reticular" which refers to the net-like appearance.

Venous malformation is a subtype of vascular malformation affecting the venous vasculature. They are usually congenital and found at birth and are treated by Schlerotherapy or Laser Therapy.

The birth defect is diagnosed by the presence of a combination of these symptoms (often on approximately ¼ of the body, though some cases may present more or less affected tissue):

- One or more distinctive port-wine stains with sharp borders

- Varicose veins

- Hypertrophy of bony and soft tissues, that may lead to local gigantism or shrinking, most typically in the lower body/legs.

- An improperly developed lymph system

In some cases, port-wine stains (capillary port wine type) may be absent. Such cases are very rare and may be classified as "atypical Klippel–Trenaunay syndrome".

KTS can either affect blood vessels, lymph vessels, or both. The condition most commonly presents with a mixture of the two. Those with venous involvement experience increased pain and complications, such as venous ulceration in the lower extremities.

Those with large AVMs are at risk of formation of blood clots in the vascular lesion, which may migrate to the lungs (pulmonary embolism). If there is large-volume blood flow through the lesion, "high-output heart failure" may develop due to the inability of the heart to generate sufficient cardiac output.

A trumpeter's wart is a cutaneous condition characterized by a firm, fibrous, hyperkeratotic nodule on the upper lip of a trumpet player.

There are three distinct types of lymphangioma, each with their own symptoms. They are distinguished by the depth and the size of abnormal lymph vessels, but all involve a malformation of the lymphic system. Lymphangioma circumscriptum can be found on the skin's surface, and the other two types of lymphangiomas occur deeper under the skin.

- Lymphangioma circumscriptum, a microcystic lymphatic malformation, resembles clusters of small blisters ranging in color from pink to dark red. They are benign and do not require medical treatment, although some patients may choose to have them surgically removed for cosmetic reasons.

- Cavernous lymphangiomas are generally present at birth, but may appear later in the child's life. These bulging masses occur deep under the skin, typically on the neck, tongue and lips, and vary widely in size, ranging from as small as a centimeter in diameter to several centimeters wide. In some cases, they may affect an entire extremity such as a hand or foot. Although they are usually painless, the patient may feel mild pain when pressure is exerted on the area. They come in the colors white, pink, red, blue, purple, and black; and the pain lessens the lighter the color of the bump.

- Cystic hygroma shares many commonalities with cavernous lymphangiomas, and some doctors consider them to be too similar to merit separate categories. However, cystic lymphangiomas usually have a softer consistency than cavernous lymphangiomas, and this term is typically the one that is applied to lymphangiomas that develop in fetuses. They usually appear on the neck (75%), arm pit or groin areas. They often look like swollen bulges underneath the skin.

Neurocutaneous melanosis is a congenital disorder characterized by the presence of congenital melanocytic nevi on the skin and melanocytic tumors in the leptomeninges of the central nervous system. These lesions may occur in the amygdala, cerebellum, cerebrum, pons, and spinal cord of patients. Although typically asymptomatic, malignancy occurs in the form of leptomeningeal melanoma in over half of patients. Regardless of the presence of malignancy, patients with symptomatic neurocutaneous melanosis generally have a poor prognosis with few treatment options. The pathogenesis of neurocutaneous melanosis is believed to be related to the abnormal postzygotic development of melanoblasts and mutations of the NRAS gene.

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.

Acroangiodermatitis of Mali (also known as "Mali acroangiodermatitis" and "Pseudo-Kaposi's sarcoma") is a rare cutaneous condition often characterized by purplish-blue to brown papules and plaques on the medial and lateral malleolus of both legs.

Acroangiodermatitis is a rare skin condition characterised by hyperplasia of pre-existing vasculature due to venous hypertension from severe chronic venous stasis. It is associated with amputees, haemodialysis (HD) patients with arteriovenous (AV) shunts, and patients with paralysed legs, hepatitis C, chronic venous insufficiency or AV malformations (AVM). Patients present with itchy, painful, confluent, violaceous or brown-black macules, papules or plaques usually at the distal lower limbs. There may be ulceration and bleeding. The histologic features are capillary proliferation and perivascular inflammation involving eosinophils in the dermis with minimal epidermal changes. Management includes compression therapy, wound care and surgical correction of AVM. Dapsone combined with leg elevation and compression, and erythromycin for HD patients with AV fistulas have also been reported. The lesions may persist for years with complications like ulceration, bleeding and infection.

Porokeratosis is a specific disorder of keratinization that is characterized histologically by the presence of a cornoid lamella, a thin column of closely stacked, parakeratotic cells extending through the stratum corneum with a thin or absent granular layer.