Currently, there is no consensus regarding type or frequency of scans following diagnosis and treatment of the primary eye tumor. Of the 50% of patients who develop metastatic disease, more than 90% of patients will develop liver metastases. As such, the majority of surveillance techniques are focused on the liver. These include abdominal magnetic resonance imaging (MRI), abdominal ultrasound and liver function tests. The scientific community is currently working to develop guidelines, but until then, each patient must take into consideration their individual clinical situation and discuss appropriate surveillance with their doctors.

Some ophthalmologists have also found promise with the use of intravitreal avastin injections in patients suffering from radiation-induced retinopathy, a side effect of plaque brachytherapy treatment, as well as imaging surveillance with SD-OCT.

Following a visual examination and a dermatoscopic exam, or "in vivo" diagnostic tools such as a confocal microscope, the doctor may biopsy the suspicious mole. A skin biopsy performed under local anesthesia is often required to assist in making or confirming the diagnosis and in defining severity. Elliptical excisional biopsies may remove the tumor, followed by histological analysis and Breslow scoring. Incisional biopsies such as punch biopsies are usually contraindicated in suspected melanomas, because of the possibility of sampling error or local implantation causing misestimation of tumour thickness. However, fears that such biopsies may increase the risk of metastatic disease seem unfounded.

Total body photography, which involves photographic documentation of as much body surface as possible, is often used during follow-up for high-risk patients. The technique has been reported to enable early detection and provides a cost-effective approach (with any digital camera), but its efficacy has been questioned due to its inability to detect macroscopic changes. The diagnosis method should be used in conjunction with (and not as a replacement for) dermoscopic imaging, with a combination of both methods appearing to give extremely high rates of detection.

A recent and novel method is the "ugly duckling sign". It is simple, easy to teach, and highly effective. Correlation of common lesion characteristics is made. Lesions that greatly deviate from the common characteristics are labeled an "Ugly Duckling", and a further professional exam is required. The "Little Red Riding Hood" sign suggests that individuals with fair skin and light-colored hair might have difficult-to-diagnose amelanotic melanomas. Extra care is required when examining such individuals, as they might have multiple melanomas and severely dysplastic nevi. A dermatoscope must be used to detect "ugly ducklings", as many melanomas in these individuals resemble non-melanomas or are considered to be "wolves in sheep's clothing". These fair-skinned individuals often have lightly pigmented or amelanotic melanomas that do not present easy-to-observe color changes and variations. Their borders are often indistinct, complicating visual identification without a dermatoscope.

Amelanotic melanomas and melanomas arising in fair-skinned individuals are very difficult to detect, as they fail to show many of the characteristics in the ABCD rule, break the "Ugly Duckling" sign and are hard to distinguish from acne scarring, insect bites, dermatofibromas, or lentigines.

Because there are no lymphatic channels to the uveal tract, metastasis occurs through local extension and/or blood borne dissemination. The most common site of metastasis for uveal melanoma is the liver; the liver is the first site of metastasis for 80%-90% of ocular melanoma patients. Other common sites of metastasis include the lung, bones and just beneath the skin (subcutaneous). Approximately 50 percent of patients will develop metastases within 15 years after treatment of the primary tumor, and the liver will be involved 90% of the time. Metastasis can occur more than 10 years after treatment of the primary tumor, and patients should not be considered cured even after a 10-year interval of monitoring. Molecular features of the tumor including Chromosome 3 status, Chromosome 6p status, and Chromosome 8q status and gene expression profiling (such as the DecisionDx-UM test) can be used to adjust this likelihood of metastasis for an individual patient.

The average survival time after diagnosis of liver metastases depends on the extent of systemic spread. The disease-free interval, the performance status, the liver substitution by metastases and the serum level of lactic dehydrogenase are the most important prognostic factors for metastatic uveal melanoma. There is currently no cure for metastatic uveal melanoma.

Even though the ideal method of diagnosis of melanoma should be complete excisional biopsy, the location of the melanoma may require alternatives. Dermatoscopy of acral pigmented lesions is very difficult but can be accomplished with diligent attention. Initial confirmation of the suspicion can be done with a small wedge biopsy or small punch biopsy. Thin deep wedge biopsies can heal very well on acral skin, and small punch biopsies can give enough clue to the malignant nature of the lesion. Once this confirmatory biopsy is done, a second complete excisional skin biopsy can be performed with a narrow surgical margin (1 mm). This second biopsy will determine the depth and invasiveness of the melanoma, and will help to define what the final treatment will be. If the melanoma involves the nail fold and the nail bed, complete excision of the nail unit might be required. Final treatment might require wider excision (margins of 0.5 cm or more), digital amputation, lymphangiogram with lymph node dissection, or chemotherapy.

It has been demonstrated that acral lentiginous melanoma has a poorer prognosis compared to that of cutaneous malignant melanoma (CMM).

The differential for OSSN includes pterygium, pingueculum, papilloma, solar keratosis, lipoma, lymphoma, chronic blepharoconjunctivitis, inflammation, melanoma, ocular pannus, pyogenic granuloma, kaposi sarcoma, keratocanthoma, mucoepidermoid carcinoma, pseudoepitheliomatous hyperplasia, and adenocarcinoma. While confocal microscopy can be used for diagnosis, biopsy is considered the standard, especially before treatment with a cytotoxic medication.

Treatment of small melanomas is often not necessary, but large tumors can cause discomfort and are usually surgically removed. Cisplatin and cryotherapy can be used to treat small tumors less than 3 centimeters, but tumors may reoccur. Cimetidine, a histamine stimulator, can cause tumors to regress in some horses, but may take up to 3 months to produce results and multiple treatments may be needed throughout the horse's life. There are few viable treatment options for horses with metastatic melanoma. However, gene therapy injections utilizing interleukin-12 and 18-encoding DNA plasmids have shown promise in slowing the progression of tumors in patients with metastatic melanoma.

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.

Treatment depends on the thickness of the invasive component of the lentigo maligna. Treatment is essentially identical to other melanomas of the same thickness and stage.

Sunscreen is effective and thus recommended to prevent melanoma and squamous-cell carcinoma. There is little evidence that it is effective in preventing basal-cell carcinoma. Other advice to reduce rates of skin cancer includes avoiding sunburning, wearing protective clothing, sunglasses and hats, and attempting to avoid sun exposure or periods of peak exposure. The U.S. Preventive Services Task Force recommends that people between 9 and 25 years of age be advised to avoid ultraviolet light.

The risk of developing skin cancer can be reduced through a number of measures including decreasing indoor tanning and mid day sun exposure, increasing the use of sunscreen, and avoiding the use of tobacco products.

There is insufficient evidence either for or against screening for skin cancers. Vitamin supplements and antioxidant supplements have not been found to have an effect in prevention. Evidence for a benefit from dietary measures is tentative.

Zinc oxide and titanium oxide are often used in sun screen to provide broad protection from UVA and UVB ranges.

Eating certain foods may decrease the risk of sunburns but this is much less than the protection provided by sunscreen.

First dilemma in diagnosis is recognition. As lentigo malignas often present on severely sun damaged skin, it is frequently found amongst numerous pigmented lesions - thin seborrheic keratoses, lentigo senilis, lentigines. It is difficult to distinguish these lesions with the naked eye alone, and even with some difficulty using dermatoscopy. As the lentigo maligna is often very large, it often merges with, or encompasses other skin tumors - such as lentigines, melanocytic nevi, and seborrheic keratosis.

Second dilemma is the biopsy technique. Even though excisional biopsy (removing the entire lesion) is ideal, and advocated by pathologists, practical reason dictates that this should not be done. These tumors are often large and presenting on the facial area. Excision of such large tumor would be absolutely contraindicated if the lesion's identity is uncertain. The preferred method of diagnosis is by using a shave biopsy because punch biopsies give up to an 80% false negative rate. While one section of the tumor might show benign melanocytic nevus, another section might show features concerning of severe cellular atypia. When cellular atypia is noted, a pathologist might indicate that the entire lesion should be removed. It is at this point that one can comfortably remove the entire lesion, thus confirming the final diagnosis of lentigo maligna. Despite the high false negative rate, punch biopsies are often used and the size of the punch biopsy can vary from 1 mm to 2 mm, but it is preferred to use a punch 1.5 mm or larger. Representative samples of the most atypical part of the nevus should be biopsy, often by the aid of dermatoscopy.

First dilemma in diagnosis is recognition. As lentigo malignas often present on severely sun-damaged skin, it is frequently found amongst numerous pigmented lesions – thin seborrheic keratoses, lentigo senilis, lentigines. It is difficult to distinguish these lesions with the naked eye alone, and even with some difficulty using dermatoscopy. As the lentigo maligna is often very large, it often merges with, or encompasses other skin tumors – such as lentigines, melanocytic nevi, and seborrheic keratosis.

Second dilemma is the biopsy technique. Even though excisional biopsy (removing the entire lesion) is ideal, and advocated by pathologists; practical reason dictates that this should not be done. These tumors are often large and presenting on the facial area. Excision of such large tumor would be absolutely contraindicated if the lesion's identity is uncertain. The preferred method of diagnosis is by using a punch biopsy, allowing the physician to sample multiple full thickness pieces of the tumor at multiple sites. While one section of the tumor might show benign melanocytic nevus, another section might show features concerning for severe cellular atypia. When cellular atypia is noted, a pathologist might indicate that the entire lesion should be removed. It is at this point that one can comfortablly remove the entire lesion, and thus confirm the final diagnosis of lentigo maligna. The size of the punch biopsy can vary from 1 mm to 2 mm, but it is preferable to use a punch 1.5 mm or larger. Representative samples of the most atypical parts of the nevus should be biopsied, often guided by dermatoscopy.

Most conjunctival squamous cell carcinomas are removed with surgery. A few selected cases are treated with topical medication. Surgical excision with a free margin of healthy tissue is a frequent treatment modality. Radiotherapy, given as external beam radiotherapy or as brachytherapy (internal radiotherapy), can also be used to treat squamous cell carcinomas.

Since 80% of grey horses will develop a melanoma tumor at some point in their lives, it is important to know what kind of treatments are available. There are several treatment options when a horse is found to have a melanoma tumor including surgical or injections:

Enucleation (surgical removal of the eye) is the treatment of choice for large ciliary body melanomas. Small or medium sized tumors may be treated by an "iridocyclectomy". Radiotherapy may be appropriate in selected cases.

The surgical removal of a melanoma tumor is performed when the tumors are small; this prevents the tumors from spreading to the surrounding areas.

The mortality rate of basal-cell and squamous-cell carcinoma are around 0.3%, causing 2000 deaths per year in the US. In comparison, the mortality rate of melanoma is 15–20% and it causes 6500 deaths per year. Even though it is much less common, malignant melanoma is responsible for 75% of all skin cancer-related deaths.

The survival rate for people with melanoma depends upon when they start treatment. The cure rate is very high when melanoma is detected in early stages, when it can easily be removed surgically. The prognosis is less favorable if the melanoma has spread to other parts of the body. As of 2003 the overall five year cure rate with Mohs' micrographic surgery was around 95 percent for recurrent basal cell carcinoma.

Australia and New Zealand exhibit one of the highest rates of skin cancer incidence in the world, almost four times the rates registered in the United States, the UK and Canada. Around 434,000 people receive treatment for non-melanoma skin cancers and 10,300 are treated for melanoma. Melanoma is the most common type of cancer in people between 15–44 years in both countries. The incidence of skin cancer has been increasing. The incidence of melanoma among Auckland residents of European descent in 1995 was 77.7 cases per 100,000 people per year, and was predicted to increase in the 21st century because of "the effect of local stratospheric ozone depletion and the time lag from sun exposure to melanoma development."

Treatment is by excisional biopsy, wide local excision and possibly sentinel node biopsy. Spread of disease to local lymph nodes or distant sites (typically brain, bone, skin and lung) marks a decidedly poor prognosis.

Clinical diagnosis can be made with the naked eye using the ABCD guideline or by using dermatoscopy. An online-screening test is also available to help screen out benign moles.

The best treatment of lentigo maligna is not clear as it has not been well studied.

Standard excision is still being done by most surgeons. Unfortunately, the recurrence rate is high (up to 50%). This is due to the ill defined visible surgical margin, and the facial location of the lesions (often forcing the surgeon to use a narrow surgical margin). The use of dermatoscopy can significantly improve the surgeon's ability to identify the surgical margin. The narrow surgical margin used (smaller than the standard of care of 5 mm), combined with the limitation of the standard bread loafing technique of fixed tissue histology - result in a high "false negative" error rate, and frequent recurrences. Margin controlled (peripheral margins) is necessary to eliminate the false negative errors. If breadloafing is utilized, distances from sections should approach 0.1 mm to assure that the method approaches complete margin control.

Where the lesion is on the face and either large or 5mm margins are possible, a skin flap or skin graft may be indicated/required. Grafts have their own risks of failure and poor cosmetic outcomes. Flaps can require extensive incision resulting in long scars and may be better done by plastic surgeons (and possibly better again by those with extensive LM or "suspicious of early malignant melanoma" experience.

Mohs surgery has been done with cure rate reported to be 77%. The "double scalpel" peripheral margin controlled excision method approximates the Mohs method in margin control, but requires a pathologist intimately familiar with the complexity of managing the vertical margin on the thin peripheral sections and staining methods.

Some melanocytic nevi, and melanoma-in-situ (lentigo maligna) have resolved with an experimental treatment, imiquimod (Aldara) topical cream, an immune enhancing agent. In view of the very poor cure rate with standard excision, some surgeons combine the two methods: surgical excision of the lesion, then three months treatment of the area with imiquimod cream.

Studies seem to conflict about the level of certainty associated with using imiquimod.

Another treatment to be considered where standard margins cannot be achieved or cosmetics are a major consideration is ultra-soft x-ray/grenz-ray radiation.

In the very elderly or those with otherwise limited life expectancy, the impact of major day surgery for excision with 5mm margins and large skin flap could be worse than doing nothing or the possibility of failed treatments with imiquimod or Grenz ray.

Therapies for metastatic melanoma include the biologic immunotherapy agents ipilimumab, pembrolizumab, and nivolumab; BRAF inhibitors, such as vemurafenib and dabrafenib; and a MEK inhibitor trametinib.

Screening for melanoma in FAMMM kindreds should begin at age 10 with a baseline total body skin examination including scalp, eyes, oral mucosa, genital area, and nail, as family members may develop melanoma in their early teens.

At Mayo Clinic, FAMMM patients with a confirmed mutation and family history of pancreatic cancer are offered screening with either high-resolution pancreatic protocol CT, MRI, or endoscopic ultrasound starting at age 50 or 10 years younger than the earliest family member with pancreas cancer. They are counseled on the lack of evidence-based data to support screening, and on the limitations of our current technology to detect a lesion at a stage amenable to therapy.

It often requires a dermatologist to fully evaluate moles. For instance, a small blue or bluish-black spot, often called a blue nevus, is usually benign but often mistaken for melanoma. Conversely, a junctional nevus, which develops at the junction of the dermis and epidermis, is potentially cancerous.

A basic reference chart used for consumers to spot suspicious moles is found in the mnemonic A-B-C-D, used by institutions such as the American Academy of Dermatology and the National Cancer Institute. The letters stand for asymmetry, border, color, and diameter. Sometimes, the letter E (for elevation or evolving) is added. According to the American Academy of Dermatology, if a mole starts changing in size, color, shape or, especially, if the border of a mole develops ragged edges or becomes larger than a pencil eraser, it would be an appropriate time to consult with a physician. Other warning signs include a mole, even if smaller than a pencil eraser, that is different from the others and begins to crust over, bleed, itch, or become inflamed. The changes may indicate developing melanomas. The matter can become clinically complicated because mole removal depends on which types of cancer, if any, come into suspicion.

A recent and novel method of melanoma detection is the "ugly duckling sign" It is simple, easy to teach, and highly effective in detecting melanoma. Simply, correlation of common characteristics of a person's skin lesion is made. Lesions which greatly deviate from the common characteristics are labeled as an "ugly duckling", and further professional exam is required. The "little red riding hood sign", suggests that individuals with fair skin and light colored hair might have difficult-to-diagnose melanomas. Extra care and caution should be rendered when examining such individuals as they might have multiple melanomas and severely dysplastic nevi. A dermatoscope must be used to detect "ugly ducklings", as many melanomas in these individuals resemble non-melanomas or are considered to be "wolves in sheep clothing". These fair skinned individuals often have lightly pigmented or amelanotic melanomas which will not present easy-to-observe color changes and variation in colors. The borders of these amelanotic melanomas are often indistinct, making visual identification without a dermatoscope very difficult.

People with a personal or family history of skin cancer or of dysplastic nevus syndrome (multiple atypical moles) should see a dermatologist at least once a year to be sure they are not developing melanoma.

It occurs most commonly in the sixth decade.

- External signs include dilated episcleral blood vessels ("sentinel vessels"). Extraocular erosion may produce a dark mass beneath the conjunctiva.

- Pressure on the lens by the enlarging tumor can cause astigmatism, sublaxtion of the lens and formation of a localised lens opacity.

- The tumor can erode forward through the iris root and mimic an iris melanoma.

- Retinal detachment can be rarely caused by posterior extension of the tumor.

- Anterior uveitis is an uncommon presentation and occurs due to tumor necrosis.

- Cirumferentially growing tumors carry a bad prognosis as they are diagnosed late.

- At times the tumor is detected as an incidental finding during routine examination.

The tumour is usually diagnosed by clinical examination with a slit-lamp utilising a triple mirror contact lens. Ultrasonography and fine needle aspiration biopsy (FNAB) are also sometimes helpful in confirming the diagnosis.