Calcinosis cutis may be divided into the following types:

- Dystrophic calcinosis cutis

- Metastatic calcinosis cutis

- Iatrogenic calcinosis cutis

- Traumatic calcinosis cutis

- Idiopathic calcinosis cutis

- Idiopathic scrotal calcinosis

- Subepidermal calcified nodule

- Tumoral calcinosis

- Osteoma cutis

Calcinosis cutis (or cutaneous calcification) is a type of calcinosis wherein calcium deposits form in the skin. A variety of factors can result in this condition. The most common source is dystrophic calcification, which occurs in soft tissue as a response to injury. In addition, calcinosis is seen in Limited Cutaneous Systemic Sclerosis, also known as CREST syndrome (the "C" in CREST). In dogs, calcinosis cutis is found in young, large breed dogs and is thought to occur after a traumatic injury.

Normophosphatemic familial tumoral calcinosis is a cutaneous disorder characterized by cutaneous calcification or ossification.

The cause is not well defined. Originally considered idiopathic condition. Now accepted that majority of cases develop from dystrophic calcification of cyst contents.

Idiopathic scrotal calcinosis (also known as idiopathic calcified nodules of the scrotum) is a cutaneous condition characterized by calcification of the skin resulting from the deposition of calcium and phosphorus occurring on the scrotum. However, the levels of calcium and phosphate in the blood are normal. Idiopathic scrotal calcinosis typically affects young males, with an onset between adolescence and early adulthood. The scrotal calcinosis appears, without any symptoms, as yellowish nodules that range in size from 1 mm to several centimeters.

Osteoma cutis is a cutaneous condition characterized by the presence of bone within the skin in the absence of a preexisting or associated lesion.

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with visible marks generally feel fine (physically) and can act normally, but when it is mentioned, they may become withdrawn and self-conscious.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.

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.

Milia-like calcinosis is a cutaneous condition characterized by small, milia-like lesions that develop on the dorsal surface of the hands and the face.

A number of conditions may cause the appearance of livedo reticularis:

- Cutis marmorata telangiectatica congenita, a rare congenital condition

- Sneddon syndrome – association of livedoid vasculitis and systemic vascular disorders, such as strokes, due to underlying genetic cause

- Idiopathic livedo reticularis – the most common form of livedo reticularis, completely benign condition of unknown cause affecting mostly young women during the winter: It is a lacy purple appearance of skin in extremities due to sluggish venous blood flow. It may be mild, but ulceration may occur later in the summer.

- Secondary livedo reticularis:

- Vasculitis autoimmune conditions:

- Livedoid vasculitis – with painful ulceration occurring in the lower legs

- Polyarteritis nodosa

- Systemic lupus erythematosus

- Dermatomyositis

- Rheumatoid arthritis

- Lymphoma

- Pancreatitis

- Chronic pancreatitis

- Tuberculosis

- Drug-related:

- Adderall (side effect)

- Amantadine (side effect)

- Bromocriptine (side effect)

- Beta IFN treatment, "i.e." in multiple sclerosis

- Livedo reticularis associated with rasagiline

- Methylphenidate and dextroamphetamine-induced peripheral vasculopathy

- Gefitinib

- Obstruction of capillaries:

- Cryoglobulinaemia – proteins in the blood that clump together in cold conditions

- Antiphospholipid syndrome due to small blood clots

- Hypercalcaemia (raised blood calcium levels which may be deposited in the capillaries)

- Haematological disorders of polycythaemia rubra vera or thrombocytosis (excessive red cells or platelets)

- Infections (syphilis, tuberculosis, Lyme disease)

- Associated with acute renal failure due to cholesterol emboli status after cardiac catheterization

- Arteriosclerosis (cholesterol emboli) and homocystinuria (due to Chromosome 21 autosomal recessive Cystathionine beta synthase deficiency)

- Intra-arterial injection (especially in drug addicts)

- Ehlers-Danlos syndrome – connective tissue disorder, often with many secondary conditions, may be present in all types

- Pheochromocytoma

- Livedoid vasculopathy and its association with factor V Leiden mutation

- FILS syndrome (polymerase ε1 mutation in a human syndrome with facial dysmorphism, immunodeficiency, livedo, and short stature)

- Primary hyperoxaluria, oxalosis (oxalate vasculopathy)

- Cytomegalovirus infection (very rare clinical form, presenting with persistent fever and livedo reticularis on the extremities and cutaneous necrotizing vasculitis of the toes)

- Generalized livedo reticularis induced by silicone implants for soft tissue augmentation

- As a rare skin finding in children with Down syndrome

- Idiopathic livedo reticularis with polyclonal IgM hypergammopathy

- CO angiography (rare, reported case)

- A less common skin lesion of Churg-Strauss syndrome

- Erythema nodosum-like cutaneous lesions of sarcoidosis showing livedoid changes in a patient with sarcoidosis and Sjögren's syndrome

- Livedo vasculopathy associated with IgM antiphosphatidylserine-prothrombin complex antibody

- Livedo vasculopathy associated with plasminogen activator inhibitor-1 promoter homozygosity and prothrombin G20210A heterozygosity

- As a first sign of metastatic breast carcinoma (very rare)

- Livedo reticularis associated with renal cell carcinoma (rare)

- Buerger's disease (as an initial symptom)

- As a rare manifestation of Graves hyperthyroidism

- Associated with pernicious anaemia

- Moyamoya disease (a rare, chronic cerebrovascular occlusive disease of unknown cause, characterized by progressive stenosis of the arteries of the circle of Willis leading to an abnormal capillary network and resultant ischemic strokes or cerebral hemorrhages)

- Associated with the use of a midline catheter

- Familial primary cryofibrinogenemia.

Cutis marmorata telangiectatica congenita or CMTC is a rare congenital vascular disorder that usually manifests in affecting the blood vessels of the skin. The condition was first recognised and described in 1922 by Cato van Lohuizen, a Dutch pediatrician whose name was later adopted in the other common name used to describe the condition - Van Lohuizen Syndrome. CMTC is also used synonymously with congenital generalized phlebectasia, nevus vascularis reticularis, congenital phlebectasia, livedo telangiectatica, congenital livedo reticularis and Van Lohuizen syndrome.

It should not be confused with the more general term "cutis marmorata", which refers to livedo reticularis caused by cold.

The cause of the rare condition of tumoral calcinosis is not entirely understood. It is generally characterized by large, globular calcifications near joints.

Metastatic calcification involves a systemic calcium excess imbalance, which can be caused by hypercalcemia, kidney failure, milk-alkali syndrome, lack or excess of other minerals, or other causes.

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.

CREST causes thickening and tightening of the skin with deposition of calcific nodules ("calcinosis").

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.

Membranous aplasia cutis is a cutaneous condition, a type of aplasia cutis congenita, which can be seen along the embryonic fusion lines of the face.

It is characterized by skin that is loose, hanging, wrinkled, and lacking in elasticity. The loose skin is often most noticeable on the face, resulting in a prematurely aged appearance. The affected areas of skin may be thickened and dark. In addition, the joints are loose (hypermobile) because of lax ligaments and tendons. When cutis laxa is severe, it can also affect the internal organs. The lungs, heart (supravalvular pulmonary stenosis), intestines, or arteries may be affected with a variety of severe impairments. In some cases, hernias and outpouching of the bladder can be observed. Patients also present with whites of the eyes that are blue.

Raynaud's phenomenon is frequently the first manifestation of CREST/lcSSc, preceding other symptoms by years. Stress and cold temperature induce an exaggerated vasoconstriction of the small arteries, arterioles, and thermoregulatory vessels of the skin of the digits. Clinically this manifests as a white-blue-red transitions in skin color. Underlying this transition is pallor and cyanosis of the digits, followed by a reactive hyperemia as they rewarm. When extreme and frequent, this phenomenon can lead to digital ulcerations, gangrene, or amputation.

Ulceration can predispose to chronic infections of the involved site.

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.

This condition is characterised by symmetrical lesions on the temples resembling forceps marks. It is characterized a puckered skin due to a virtual absence of subcutaneous fat. It is apparent at birth. Other lesions that may be present include puffy, wrinkled skin around the eyes and/or abnormalities of the eyelashes, eyebrows, and eyelids. The eyebrows may be up slanting or outward slanting. Occasionally the bridge of the nose may appear flat, while the tip may appear unusually rounded. The chin may be furrowed. The upper lip may be prominent with a down turned mouth. Other features that have been reported include dysplastic and low set ears, linear radiatory impressions on the forehead and congenital horizontal nystagmus.

Those with the Setleis syndrome may be missing eyelashes on both the upper and lower lids or may have multiple rows of lashes on the upper lids but none on the lower lids.A possible association with intra abdominal cancer has been reported but to date this has not been confirmed in other studies.

Sclerodactyly is a localized thickening and tightness of the skin of the fingers or toes. Sclerodactyly often leads to ulceration of the skin of the distal digits and is commonly accompanied by atrophy of the underlying soft tissues.

The term "sclerodactyly" is made up from the Greek "skleros" meaning hard and "daktylos" meaning a finger or toe – "hard fingers or toes".

It is sometimes associated with scleroderma and mixed connective tissue disease, auto-immune disorders.

Sclerodactyly is a component of the CREST variant of scleroderma (CREST is an acronym that stands for calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia.)

CVG is classified according to the presence, or lack of underlying cause. Studies suggest that CVG often occurs in individuals in a secondary form to other ailments. However, the condition can also be present on its own. CVG can be classified into two forms: ‘primary’ (essential and non-essential) and ‘secondary’.

The classifications are:

Primary essential CVG is where the cause of the condition in unknown. It has no other associated abnormalities. This occurs mainly in men, with a male:female ratio of 5 or 6:1, and develops during or soon after puberty. Because of the slow progression of the condition, which usually occurs without symptom, it often passes unnoticed in the early stage

Primary non essential CVG can be associated with neuropsychiatric disorders including cerebral palsy, epilepsy, seizures and ophthalmologic abnormalities, most commonly cataracts.

Secondary CVG occurs as a consequence of a number of diseases or drugs that produce changes in scalp structure. These include: acromegaly (excessive growth hormone levels due to pituitary gland tumours), excessive drug use that mimics acromegaly (including the injection of growth hormone itself and drugs that stimulate growth hormone output, such as GHRP-6 and CJC-1295), melanocytic naevi (moles), birthmarks (including connective tissue naevi, fibromas and naevus lipomatosus), and inflammatory processes (e.g., eczema, psoriasis, Darier disease, folliculitis, impetigo, atopic dermatitis, acne).

Anetoderma (also known as "Anetoderma maculosa," "Anetoderma maculosa cutis," "Atrophia maculosa cutis," and "Macular atrophy") is a localized laxity of the skin with herniation or outpouching resulting from abnormal dermal elastic tissue. Anetoderma comes in three types:

- "Primary anetoderma"

- Jadassohn–Pellizzari anetoderma is a benign condition with focal loss of dermal elastic tissue. Jadassohn-Pellizzari is one of two major classifications of primary anetoderma, the other being Schweninger–Buzzi anetoderma. The difference between the two is that Jadassohn–Pellizzari anetoderma is preceded by inflammatory lesions.

- Schweninger–Buzzi anetoderma is a cutaneous condition characterized by loss of dermal elastic tissue.

- "Secondary anetoderma"

- "Familial anetoderma"

Cutis marmorata also occurs in decompression sickness (DCS). Although it is considered Type I DCS, which is non-neurological, it is typically treated as if the patient has the more severe Type II DCS. This is because past experience in diving medicine has shown that patients initially presented with only this symptom have a high likelihood of progression to neurological, Type II, DCS without prompt treatment. The marbling does not resolve until few days after treatment, but any pruritus (itching) will likely disappear upon initial recompression.