The etiology of florid cutaneous papillomatosis is unknown. It is likely directly induced by an underlying neoplasm secreting a growth factor. One candidate may be alpha-transforming growth factor, structurally related to epidermal growth factor, but antigenically distinct from it. The underlying cancer is most often gastric adenocarcinoma but also with breast cancer, bladder cancer, hepatobiliary cancer, ovarian cancer, uterine cancer, prostate cancer, lung cancer and cervical cancer. Other associated underlying malignancies include squamous cell carcinomas and lymphomas.

Lymphoma is the most common type of blood-related cancer in horses and while it can affect horses of all ages, it typically occurs in horses aged 4–11 years.

An acanthoma is a skin neoplasm composed of squamous or epidermal cells. It is located in the prickle cell layer.

Types of acanthoma include pilar sheath acanthoma, a benign follicular tumor usually of the upper lip; clear cell acanthoma, a benign tumor found most frequently on the legs; and Degos acanthoma, often confused with but unrelated to Degos disease.

Florid cutaneous papillomatosis is almost twice as common in men than in women, and is usually diagnosed in individuals aged 53–72 years (mean patient age, 58.5 years).

Trichoepithelioma is a neoplasm of the adnexa of the skin. Its appearance is similar to basal cell carcinoma.

One form has been mapped to chromosome 9p21.

The tumor is rare, affecting adults in the 4th decade most commonly. Patients are usually younger than those who present with a lipoma. There is a slight male predominance. Hibernoma are most commonly identified in the subcutaneous and muscle tissue of the head and neck region (shoulders, neck, scapular), followed by thigh, back, chest, abdomen, and arms. In rare cases hibernoma may arise in bone tissue, however it is an incidental finding.

Extramammary Paget's disease is usually seen in isolation and is associated with an underlying invasive malignancy about 12% of the time. It is associated with an underlying adnexal malignancy about 24% of the time. Paget's disease of the breast is almost always associated with an underlying invasive malignancy, i.e. breast cancer (e.g. mammary ductal carcinoma).

Trichilemmoma (also known as "tricholemmoma") is a benign cutaneous neoplasm that shows differentiation toward cells of the outer root sheath. The lesion is often seen in the face and neck region. Multifocal occurrence is associated with Cowden syndrome, in which hamartomatous intestinal polyposis is seen in conjunction with multiple tricholemmoma lesions.

Proliferating trichilemmal cysts (also known as a "Pilar tumor", "Proliferating follicular cystic neoplasm", "Proliferating pilar tumor", and "Proliferating trichilemmal tumor") are a cutaneous condition characterized by proliferations of squamous cells forming scroll-like structures.

Equine melanoma results from abnormal proliferation and accumulation of melanocytes, pigmented cells within the dermis. Gray horses over 6-years-old are especially prone to developing melanoma. The prevalence of melanoma in gray horses over 15 years old has been estimated at 80%. One survey of Camargue-type horses found an overall population prevalence of 31.4%, with prevalence increasing to 67% in horses over 15 years old. Up to 66% of melanomas in gray horses are benign, but melanotic tumors in horses with darker hair-coats may be more aggressive and are more often malignant. One retrospective study of cases sent to a referral hospital reported a 14% prevalence of metastatic melanoma within the study population. However, the actual prevalence of metastatic melanoma may be lower due to infrequent submission of melanotic tumors for diagnosis. Common sites for metastasis include lymph nodes, the liver, spleen, lung, skeletal muscle, blood vessels and parotid salivary gland.

Papillary eccrine adenoma (also known as "tubular apocrine adenoma") is a cutaneous condition characterized by an uncommon benign sweat gland neoplasm that presents as a dermal nodule located primarily on the extremities of black patients.

An odontogenic keratocyst is a rare and benign but locally aggressive developmental cyst. It most often affects the posterior mandible. It most commonly presents in the third decade of life.

In the WHO/IARC classification of head and neck pathology, this clinical entity had been known for years as the odontogenic keratocyst; it was reclassified as keratocystic odontogenic tumour (KCOT) from 2005 to 2017. In 2017 it reverted to the earlier name, as the new WHO/IARC classification reclassified OKC back into the cystic category. The WHO/IARC classification no longer considers it a neoplasm, because the evidence supporting that hypothesis (for example, clonality) is considered insufficient. However, this is an area of hot debate within the head and neck pathology community, and some pathologists still regard OKC as a neoplasm despite the reclassification.

A superficial acral fibromyxoma is a type of myxoma and is a rare cutaneous condition characterized by a mesenchymal neoplasm that typically occurs on the digits of middle-age adults.

An odontogenic tumor is a neoplasm of the cells or tissues that initiate odontogenic processes.

Examples include:

- Adenomatoid odontogenic tumor

- Ameloblastoma, a type of odontogenic tumor involving ameloblasts

- Calcifying epithelial odontogenic tumor

- Keratocystic odontogenic tumor

- Odontogenic myxoma

- Odontoma

KCOTs are thought to arise from the dental lamina and are associated with impacted teeth. Multiple odontogenic keratocysts are a feature of nevoid basal cell carcinoma syndrome.

Odotogenic Keratocysts are derived from the remnants of the Dental Lamina.

Sebaceous carcinoma is an uncommon and aggressive malignant cutaneous tumor. Most are typically about 10 mm in size at presentation. This neoplasm is thought to arise from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. Because the periocular region is rich in this type of gland, this region is a common site of origin. The cause of these lesions are, in the vast majority of cases, unknown. Occasional cases may be associated with Muir-Torre syndrome.

This type of cancer usually has a poor prognosis because of a high rate of metastasis.

Microvenular hemangioma (also known as "Microcapillary hemangioma") is an acquired benign vascular neoplasm that presents as an asymptomatic, slowly growing, 0.5- to 2.0 cm reddish lesion on the forearms or other sites of young to middle-aged adults.

A myxoid liposarcoma is a malignant adipose tissue neoplasm of myxoid appearance histologically.

Myxoid liposarcomas are the second most common type of liposarcoma, representing 30–40% of all liposarcomas in the limbs; occurring most commonly in the legs, particularly the thigh, followed by the buttocks, retroperitoneum, trunk, ankle, proximal limb girdle, head and neck, and wrist. They occur in the intermuscular fascial planes or deep-seated areas. They present as a large, slow-growing, painless mass.

They are associated with a fusion between DDIT3 or "CHOP" (at 12q13.1-q13.2) and FUS or "TLS" (at 16p11.2) or EWS (at 22q12.2).

The specific translocation of FUS-DDIT3 is t(12;16)(q13;p11).

A hibernoma is a benign neoplasm of vestigial brown fat. The term was originally used by Gery in 1914.

The cell of origin is usually unknown. Sebaceous gland carcinoma clearly resembles normal sebaceous glands and is thought to arise from them.

Paget's disease of the vulva, a rare disease, may be a primary lesion or associated with adenocarcinoma originating from local organs such as the Bartholin gland, the urethra, or the rectum and thus be secondary. Patients tend to be postmenopausal.

Paget's disease of the penis may also be primary or secondary, and is even rarer than genital Paget’s disease in women. At least one case has been misdiagnosed as Bowen's disease. Isolated Paget's disease of the penis is extremely rare.

Trichoepitheliomas consisted of nests of basaloid cells. They lack the myxoid stroma and artefactual clefting seen in basal cell carcinoma. Mitoses are uncommon when compared to basal cell carcinoma.

SCTC exhibits a highly aggressive phenotype, thus prognosis of that malignancy is extremely poor. The overall survival is less than 1 year in most of cases.

Syringomas can be found in association with other symptoms as part of a syndrome. Hailey-Hailey disease also known as familial benign chronic pemphigus is a blistering disease that can also include syringomas.

Several systemic syndromes have also been associated with syringoma including diabetes mellitus, down syndrome, Brooke-Spiegler, and Nicolau-Balus. Specifically, diabetes mellitus is strongly associated with clear cell syringoma consisting of nests of clear cells containing glycogen. It is thought that phosphorylase deficiency, resulting from elevated glucose levels seen in diabetes leads to an accumulation of glycogen in the skin and within the clear cells. The incidence of syringomas has been reported in up to 40 percent of people with Down syndrome and can be associated with a condition calcinosis cutis which requires prompt medical attention. Brooke-Spiegler syndrome is a rare autosomal dominant syndrome with cutaneous manifestations including syringomas and trichoepitheliomas. Nicolau-Balus is a rare autosomal dominant disorder consisting of atrophoderma vermiculata and syringomas.

Carcinoma "in situ" is, by definition, a localized phenomenon, with no potential for metastasis unless it progresses into cancer. Therefore, its removal eliminates the risk of subsequent progression into a life-threatening condition.

Some forms of CIS (e.g., colon polyps and polypoid tumours of the bladder) can be removed using an endoscope, without conventional surgical resection. Dysplasia of the uterine cervix is removed by excision (cutting it out) or by burning with a laser. Bowen's disease of the skin is removed by excision. Other forms require major surgery, the best known being intraductal carcinoma of the breast (also treated with radiotherapy). One of the most dangerous forms of CIS is the "pneumonic form" of BAC of the lung, which can require extensive surgical removal of large parts of the lung. When too large, it often cannot be completely removed, with eventual disease progression and death of the patient.