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.

The characteristic eruption is of multiple warty papules and nodules beginning on acral skin, especially the hands and wrists, and disseminating onto the skin of the entire body. These skin lesions develop on the trunk, extremities, and face, and are almost twice as common in men than in women, especially individuals aged 53–72 years. Pruritus is also associated.

Cutaneous horns, also known by the Latin name cornu cutaneum, are unusual keratinous skin tumors with the appearance of horns, or sometimes of wood or coral. Formally, this is a clinical diagnosis for a "conical projection above the surface of the skin." They are usually small and localized, but can, in very rare cases be much larger. Although often benign, they can also be malignant or premalignant.

The lesion at the base of the keratin mound is benign in the majority of cases. Malignancy is present in up to 20% of cases, with squamous cell carcinoma being the most common type. The incidence of squamous cell carcinoma increases to 37% when the cutaneous horn is present on the penis. Tenderness at the base of the lesion is often a clue to the presence of a possible underlying squamous cell carcinoma.

Papillomatosis cutis carcinoides (also known as "Gottron's carcinoid papillomatosis" and "Papillomatosis cutis carcinoides of Gottron–Eisenlohr") is a cutaneous condition characterized by verrucous skin lesions, and is due to an HPV infection of the skin.

Oral florid papillomatosis is a condition characterized by a white mass resembling a cauliflower covering the tongue and extending onto other portions of the mucous membranes. This is a type of verrucous carcinoma.

Blue nevi may be divided into the following types:

- A "patch blue nevus" (also known as an "acquired dermal melanocytosis", and "dermal melanocyte hamartoma") is a cutaneous condition characterized by a diffusely gray-blue area that may have superimposed darker macules.

- A "blue nevus of Jadassohn–Tièche" (also known as a "common blue nevus", and "nevus ceruleus") is a cutaneous condition characterized by a steel-blue papule or nodule.

- A "cellular blue nevus" is a cutaneous condition characterized by large, firm, blue or blue-black nodules.

- An "epithelioid blue nevus" is a cutaneous condition most commonly seen in patients with the Carney complex.

- A "deep penetrating nevus" is a type of benign melanocytic skin tumor characterized, as its name suggests, by penetration into the deep dermis and/or subcutis. Smudged chromatic is a typical finding. In some cases mitotic figures or atypical melanocytic cytology are seen, potentially mimicking a malignant melanoma. Evaluation by an expert skin pathologist is advisable in some cases to help differentiate from invasive melanoma.

- An "amelanotic blue nevus" (also known as a "hypomelanotic blue nevus") is a cutaneous condition characterized by mild atypia and pleomorphism.

- A "malignant blue nevus" is a cutaneous condition characterized by a sheet-like growth pattern, mitoses, necrosis, and cellular atypia.

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.

Secondary cutaneous amyloidosis is a skin condition that occurs following PUVA therapy and in benign and malignant cutaneous neoplasms in which deopsits of amyloid may be found.

Blue nevus (also known as "blue neuronevus", "dermal melanocytoma", and "nevus bleu") is a type of melanocytic nevus. The blue colour is caused by the pigment being deeper in the skin than in ordinary nevi. In principle they are harmless but they can sometimes be mimicked by malignant lesions, i.e. some melanomas can look like a blue nevus.

Non-mycosis fungoides CD30− cutaneous large T-cell lymphoma is a cutaneous condition that usually presents as solitary or generalized plaques, nodules, or tumors of short duration.

"Configuration" refers to how lesions are locally grouped ("organized"), which contrasts with how they are distributed (see next section).

- Agminate: in clusters

- Annular or circinate: ring-shaped

- Arciform or arcuate: arc-shaped

- Digitate: with finger-like projections

- Discoid or nummular: round or disc-shaped

- Figurate: with a particular shape

- Guttate: resembling drops

- Gyrate: coiled or spiral-shaped

- Herpetiform: resembling herpes

- Linear

- Mammillated: with rounded, breast-like projections

- Reticular or reticulated: resembling a net

- Serpiginous: with a wavy border

- Stellate: star-shaped

- Targetoid: resembling a bullseye

- Verrucous: wart-like

A cutaneous condition is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment.

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 causes 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), cause (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). The 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. The introduction of cutaneous ultrasound has allowed the detection of cutaneous tumors, inflammatory processes, nail disorders and hair diseases.

Multiple cutaneous leiomyomas, also known as Pilar leiomyomas, arise from the arrectores pilorum muscles, and are made up of a poorly circumscribed proliferation of haphazardly arranged smooth muscle fibers located in the dermis that appear to infiltrate the surrounding tissue and may extend into the subcutis.

Sometimes associated with uterine leiomyomas (a combination known as multiple cutaneous and uterine leiomyomatosis, MCUL), these lesions may also be a manifestation of the hereditary leiomyomatosis and renal cell cancer syndrome.

A common symptom of laryngeal papillomatosis is a perceptual change in voice quality. More specifically, hoarseness is observed. As a consequence of the narrowing of the laryngeal or tracheal parts of the airway, shortness of breath, chronic cough and stridor (i.e. noisy breathing which can sound like a whistle or a snore), can be present. As the disease progresses, occurrence of secondary symptoms such as dysphagia, pneumonia, acute respiratory distress syndrome, failure to thrive, and recurrent upper respiratory infections can be diagnosed. In children, symptoms are usually more severe and often mistaken for manifestations of other diseases such as asthma, croup or bronchitis. Therefore, diagnosis is usually delayed.

Cutaneous lymphoid hyperplasia refers to a groups of benign cutaneous disorders characterized by collections of lymphocytes, macrophages, and dendritic cells in the skin. Conditions included in this groups are:

- Cutaneous lymphoid hyperplasia with nodular pattern, a condition of the skin characterized by a solitary or localized cluster of asymptomatic erythematous to violaceous papules or nodules

- Cutaneous lymphoid hyperplasia with bandlike and perivascular patterns, a condition of the skin characterized by skin lesions that clinically resemble mycosis fungoides

Lichen planus affecting mucosal surfaces may have one lesion or be multifocal. Examples of lichen planus affecting mucosal surfaces include:

- "Esophageal lichen planus", affecting the esophageal mucosa. This can present with difficulty or pain when swallowing due to oesophageal inflammation, or as the development of an esophageal stricture. It has also been hypothesized that it is a precursor to squamous cell carcinoma of the esophagus.

- "Genital lichen planus," which may cause lesions on the glans penis or skin of the scrotum in males, and the vulva or vagina in females. Symptoms may include lower urinary tract symptoms associated with stenosis of the urethra, painful sexual intercourse, and itching. In females, "Vulvovaginal-gingival syndrome," is severe and distinct variant affecting the vulva, vagina, and gums, with complications including scarring, vaginal stricture formation, or vulva destruction. The corresponding syndrome in males, affecting the glans penis and gums, is the "peno-gingival syndrome". It is associated with HLA-DQB1.

Although lichen planus can present with a variety of lesions, the most common presentation is as a well defined area of purple-coloured, itchy, flat-topped papules with interspersed lacy white lines (Wickham's striae). This description is known as the characteristic "6 Ps" of lichen planus: planar (flat-topped), purple, polygonal, pruritic, papules, and plaques. This rash, after regressing, is likely to leave an area of hyperpigmentation that slowly fades. That said, a variety of other lesions can also occur.

Benign neonatal hemangiomatosis is a cutaneous condition in infants, characterized by multiple cutaneous lesions without evident visceral hemangiomas.

Large plaque parapsoriasis (also known as "parapsoriasis en plaques") are skin lesions that may be included in the modern scheme of cutaneous conditions described as parapsoriasis. These lesions, called plaques, may be irregularly round-shaped to oval and are or larger in diameter. They can be very thin plaques that are asymptomatic or mildly pruritic. Large-plaque parapsoriasis is a common associate of retiform parapsoriasis, can be accompanied by poikiloderma vasculare atrophicans, and can in rare occasions be a precursor to cutaneous T-cell lymphoma.

Cutaneous ciliated cysts are a cutaneous condition characterized by solitary cysts located on the legs of females.

Howel–Evans syndrome is an extremely rare condition involving thickening of the skin in the palms of the hands and the soles of the feet (hyperkeratosis). This familial disease is associated with a high lifetime risk of esophageal cancer. For this reason, it is sometimes known as tylosis with oesophageal cancer (TOC).

The condition is inherited in an autosomal dominant manner, and it has been linked to a mutation in the "RHBDF2" gene. It was first described in 1958.

Retiform parapsoriasis is a cutaneous condition, considered to be a type of large-plaque parapsoriasis. It is characterized by widespread, ill-defined plaques on the skin, that have a net-like or zebra-striped pattern. Skin , a wasting away of the cutaneous tissue, usually occurs within the area of these plaques.

The differential diagnosis is quite extensive and includes

- Buschke–Fischer–Brauer disease

- Curth–Macklin ichthyosis

- Gamborg Nielsen syndrome

- Greither disease

- Haber syndrome

- Hereditary punctate palmoplantar keratoderma

- Jadassohn–Lewandowsky syndrome

- Keratosis follicularis spinulosa decalvans

- Keratosis linearis with ichthyosis congenital and sclerosing keratoderma syndrome

- Meleda disease

- Mucosa hyperkeratosis syndrome

- Naegeli–Franceschetti–Jadassohn syndrome

- Naxos disease

- Olmsted syndrome

- Palmoplantar keratoderma and leukokeratosis anogenitalis

- Pandysautonomia

- Papillomatosis of Gougerot and Carteaud

- Papillon–Lefèvre syndrome

- Punctate porokeratotic keratoderma

- Richner–Hanhart syndrome

- Schöpf–Schulz–Passarge syndrome

- Unna Thost disease

- Vohwinkel syndrome

- Wong's dermatomyositis

Papillomatosis is skin surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae. These papillary projections of the epidermis form an undulating surface under microscopic examination.