Cutaneous perforating disorders include the following:

- Acquired perforating dermatosis (Acquired perforating collagenosis)

- Kyrle disease

- Perforating folliculitis

The causes of Kyrle disease are unclear and can be idiopathic. The only correlation that has shown light is the frequent association with an underlying disorder, such as, diabetes mellitus, chronic renal failure, hyperlipoproteinemia, hepatic abnormalities, and congestive heart failure. However, there had been cases where Kyrle disease was seen without any conjunction with the previous mentioned disorders. Due to the causes of Kyrle disease is unknown, the best way to prevent the disease is to prevent the disorders that are usually reported in conjunction with it.

Morbidity and mortality range from both extremes as the significance correlate with the underlying systemic disease.

Acquired perforating dermatosis (also known as "Acquired perforating collagenosis") is clinically and histopathologically similar to perforating folliculitis, also associated with chronic kidney failure, with or without hemodialysis or peritoneal dialysis, and/or diabetes mellitus, but not identical to Kyrle disease.

Verrucous perforating collagenoma is a very rare skin disorder which presents with papules with a transepidermal elimination of collagen.

Reactive perforating collagenosis is a rare, familial, nonpuritic skin disorder characterized by papules that grow in a diameter of 4 to 6mm and develop a central area of umbilication to which keratinous material is lodged. The cause of reactive perforating collagenosis is unknown.

DPN is not a premalignant condition nor is it associated with any underlying systemic disease. DPN lesions show no tendency to regress spontaneously, and often increase in size and number as an individual ages.

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.

In general, sebaceous adenitis is underdiagnosed in dogs. Diagnosis confirmation requires multiple punch biopsies analysed by a dermopathologist who will comment on the condition of the sebaceous glands, revealing granulomatous or pyogranulomatous inflammation surrounding the sebaceous glands or even complete destruction of sebaceous glands.

Other conditions with similar presentations include: bacterial folliculitis and demodicosis, dermatophytosis, endocrinopathy, pemphigus foliaceus, zinc responsive dermatosis, vitamin A-responsive dermatosis, ichthyosis, and nutritional deficiencies. As well as, superficial pyoderma, primary idiopathic seborrhea and other endocrine diseases.

Perforating granuloma annulare is a skin condition of unknown cause, usually appearing on the dorsal hands, presenting as papules with a central keratotic core.

Perforating calcific elastosis (also known as "Localized acquired cutaneous pseudoxanthoma elasticum," "Perforating periumbilical calcific elastosis," and "Periumbilical perforating pseudoxanthoma elasticum") is an acquired, localized cutaneous disorder, most frequently found in obese, multiparous, middle-aged women, characterized by lax, well-circumscribed, reticulated or cobble-stoned plaques occurring in the periumbilical region with keratotic surface papules.

While the condition has been seen in over 60 breeds of dog (including cross breeds), certain breeds have been found to be more susceptible than others to sebaceous adenitis:

- American Akita and Akita Inu

- Standard Poodle

- Vizsla

- English Springer Spaniel

- Chow Chow

- Samoyed

- Weimaraner

- Havanese

Breeds also mentioned in scientific literature as having some susceptibility include:

- German Shepherd

- Dachshund

- Old English Sheepdog

- Lhasa Apso

- Boxer

- Collie

- Toy Poodle

- Mixed-breeds

Sebaceous adenitis has no sex-predisposition. Sebaceous adenitis also occurs in cats, rabbits and horses.

Urticaria is a vascular reaction of the skin characterized by the appearance of wheals, which are firm, elevated swelling of the skin. Angioedema, which can occur alone or with

urticaria, is characterized by a well-defined, edematous swelling that involves subcutaneous tissues, abdominal organs, or upper airway.

- Acquired C1 esterase inhibitor deficiency

- Acute urticaria

- Adrenergic urticaria

- Anaphylaxis

- Aquagenic urticaria

- Cholinergic urticaria

- Chronic urticaria (ordinary urticaria)

- Cold urticaria

- Dermatographism (dermographism)

- Episodic angioedema with eosinophilia (Gleich's syndrome)

- Exercise urticaria (exercise-induced urticaria)

- Galvanic urticaria

- Heat urticaria

- Hereditary angioedema (Quincke's edema)

- Localized heat contact urticaria

- Mast cell-independent urticaria

- Physical urticaria

- Primary cold contact urticaria

- Pressure urticaria (delayed pressure urticaria)

- Reflex cold urticaria

- Schnitzler syndrome

- Secondary cold contact urticaria

- Solar urticaria

- Systemic capillary leak syndrome

- Urticarial allergic eruption

- Urticaria-like follicular mucinosis

- Vibratory angioedema

Sweet's syndrome-like dermatosis is a cutaneous condition associated with bowel disorders.

Pustulosis palmaris et plantaris (also known as pustulosis of palms and soles, palmoplantar pustulosis, persistent palmoplantar pustulosis, pustular psoriasis of the Barber type, and pustular psoriasis of the extremities) is a chronic recurrent pustular dermatosis (that is, a pustulosis or pustular psoriasis) localized on the palms and soles only, characterized histologically by intraepidermal pustules filled with neutrophils. It can occur as part of the SAPHO syndrome.

Pemphigus foliaceus has been recognized in pet dogs, cats, and horses and is the most common autoimmune skin disease diagnosed in veterinary medicine. Pemphigus foliaceus in animals produces clusters of small vesicles that quickly evolve into pustules. Pustules may rupture, forming erosions or become crusted. Left untreated, pemphigus foliaceus in animals is life-threatening, leading to not only loss of condition but also secondary infection.

Pemphigus vulgaris is a very rare disorder described in pet dogs and cats. Paraneoplastic pemphigus has been identified in pet dogs.

Elastosis perforans serpiginosa is a unique perforating disorder characterized by transepidermal elimination of elastic fibers and distinctive clinical lesions, which are serpiginous in distribution and can be associated with specific diseases.

Neutrophilic dermatosis of the dorsal hands (also known as "Pustular vasculitis of the dorsal hands") is a skin condition that presents with edematous pustular or ulcerative nodules or plaques localized to the dorsal hands.

Although it may occur in the absence of other known disease, SS is often associated with hematologic disease (including leukemia), and immunologic disease (rheumatoid arthritis, inflammatory bowel disease, Behçet's syndrome).

A genetic association has been suggested, but no specific genetic link has been identified.

PUVA-induced acrobullous dermatosis is a cutaneous condition characterized by the sudden occurrence of tense blisters, usually on the distal extremities, during long-term PUVA therapy

DPN affects up to 35% of the African American population in the USA Insufficient data is available on the international frequency of DPN.

Lesions generally emerge during puberty, increasing steadily in number and size as an individual ages.

Black people with a fair complexion have the lowest frequency of involvement. DPN also occurs among Asians, although the exact incidence is unknown. Females are affected more frequently than males. Dermatosis papulosa nigra generally emerges in adolescence and is rarely in persons younger than 7 years The incidence, size and number of lesions of DPN increases with age.

Pigmented purpuric dermatosis (also known as "progressive pigmentary dermatosis," "purpura pigmentosa chronica," "pigmentary purpuric eruptions," or "progressive pigmenting purpura" or "Schamberg's disease") refers to one of the three major classes of skin conditions characterized by purpuric skin eruptions.

Pigmented purpuric dermatosis are distinguished from other purpura by size (0.3–1 cm) and are most often seen in the lower extremities. Pigmentary purpuric eruptions may present with one of several clinical patterns. There may be overlapping characteristics among pigmented purpuric dermatosis and between their signs and those of other purpuric eruptions. Examples of the pigmented purpuric dermatosis group include:

Although vascular damage may be present, it is insufficient for these conditions to be considered forms of vasculitis.

Pemphigus ( or ) is a rare group of blistering autoimmune diseases that affect the skin and mucous membranes. The name is derived from the Greek root "pemphix" meaning "pustule".

In pemphigus, autoantibodies form against desmoglein. Desmoglein forms the "glue" that attaches adjacent epidermal cells via attachment points called desmosomes. When autoantibodies attack desmogleins, the cells become separated from each other and the epidermis becomes "unglued", a phenomenon called acantholysis. This causes blisters that slough off and turn into sores. In some cases, these blisters can cover a significant area of the skin.

Originally, the cause of this disease was unknown, and "pemphigus" was used to refer to any blistering disease of the skin and mucosa. In 1964, researchers found that the blood of patients with pemphigus contained antibodies to the layers of skin that separate to form the blisters. In 1971, an article investigating the autoimmune nature of this disease was published.

SS is a reactive phenomenon and should be considered a cutaneous marker of systemic disease. Careful systemic evaluation is indicated, especially when cutaneous lesions are severe or hematologic values are abnormal. Approximately 20% of cases are associated with malignancy, predominantly hematological, especially acute myelogenous leukemia (AML). An underlying condition (streptococcal infection, inflammatory bowel disease, nonlymphocytic leukemia and other hematologic malignancies, solid tumors, pregnancy) is found in up to 50% of cases. Attacks of SS may precede the hematologic diagnosis by 3 months to 6 years, so that close evaluation of patients in the “idiopathic” group is required.

There is now good evidence that treatment with hematopoietic growth factors — including granulocyte colony-stimulating factor (G-CSF), which is used to treat AML, and granulocyte-macrophage colony-stimulating factor — can cause SS. Lesions typically occur when the patient has leukocytosis and neutrophilia but not when the patient is neutropenic. However, G-CSF may cause SS in neutropenic patients because of the induction of stem cell proliferation, the differentiation of neutrophils, and the prolongation of neutrophil survival.

Erosive pustular dermatitis of the scalp (also known as "Erosive pustular dermatosis of the scalp") presents with pustules, erosions, and crusts on the scalp of primarily older Caucasean females, and on biopsy, has a lymphoplasmacytic infiltrate with or without foreign body giant cells and pilosebaceous atrophy.