A lesion biopsy is performed if the diagnosis remains uncertain after a clinical physical exam. The most common tissue sampling techniques include shave or punch biopsy. When only a portion of the lesion can be removed due to its size or location, the biopsy should sample tissue from the thickest area of the lesion, as SCCs are most likely to be detected in that area. If a shave biopsy is performed, it should extend through to the level of the dermis in order to provide sufficient tissue for diagnosis; ideally, it would extend to the mid-reticular dermis. Punch biopsy usually extends to the subcutaneous fat when the entire length of the punch blade is utilized.

Dermoscopy is a noninvasive technique utilizing a handheld magnifying device coupled with a transilluminating lift. It is often used in the evaluation of cutaneous lesions, but lacks the definitive diagnostic ability of biopsy-based tissue diagnosis. Histopathologic exam remains the gold standard

Primary diagnosis usually starts off with a thorough physical exam and evaluation of medical history. To further investigate, a dermoscope, a diagnostic tool, is used by the dermatologist to examine the skin using a magnified lens. A complete blood count (CBC) along with other blood tests can also be done to rule out any sort of other infections. Lastly, a skin biopsy test may be ordered to arrive at a definitive diagnosis. This pathological examination of the skin biopsy helps to arrive at the correct diagnosis via a fungal culture(mycology). The biopsy is put together with clinical and microscope findings and study of the special tissues if need be. The signs and symptoms of MG are similar to many other clinical conditions and therefore it is necessary to perform all of the additional tests in order for a physician to correctly rule out all other possible diagnoses.

The exact cause of Majocchi's granuloma is not well established however a dysfunctinoal immune system may be a causative factor. The first form of MG, the superficial perifollicular form occurs predominately on the legs of otherwise healthy young women who repeatedly shave their legs and develop hair follicle occlusions that directly or indirectly disrupt the follicle and allow for passive introduction of the organism into the dermis. Hence, the physical barrier of the skin is important because it prevents the penetration of microorganisms. Physical factors that play a major role in inhibiting dermal invasion include the interaction among keratin production, the rate of epidermal turnover, the degree of hydration and lipid composition of the stratum corneum, CO levels, and the presence or absence of hair. Keratin and/or necrotic material can also be introduced into the dermis with an infectious organism to further enhance the problem. In immunocompromised individuals, the use of topical corticosteroids may lead to a dermatophyte infection due to local immunosuppression.

Actinic granuloma (also known as "O'Brien granuloma") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

Actinic granuloma is an asymptomatic granulomatous reaction that affects sun-exposed skin, most commonly on the face, neck, and scalp.

It is characterized by annular or polycyclic lesions that slowly expand centrifugally and have an erythematous elevated edge and a hypopigmented, atrophic center.

Advise to reduce exposure to the sun and to use sunscreen.

Treatment with topical halometasone cream, pimecrolimus cream.

Due to its overwhelming incidence on the gingiva, the condition is often associated with two other diseases, though not because they occur together. Instead, the three are associated with each other because they appear frequently on gingiva—peripheral giant cell granuloma and peripheral ossifying fibroma. Detailed analysis can be used to distinguish these conditions.

Because granuloma annulare is usually asymptomatic and self-limiting with a course of about 2 years, initial treatment is generally topical steroid creams, followed by oral steroids and finally intradermal injections at the site of each ring. Treatment success varies widely, with most patients finding only brief success with the above-mentioned treatments. New research out of India suggests that the combination of rifampin (600 mg), ofloxacin (400 mg), and minocycline hydrochloride (100 mg) once monthly, or ROM therapy, produces promising results. Most lesions of granuloma annulare disappear in pre-pubertal patients with no treatment within two years while older patients (50+) have rings for upwards of 20 years. The appearance of new rings years later is not uncommon.

Prognosis is usually good, however recurrence may happen with rate up to 16%. Presence of myxoid structures in the pyogenic granuloma may be the main cause of recurrence.

Although pyogenic granulomas are not infectious or malignant, treatment may be considered because of bleeding or ulceration. Frequently, pyogenic granulomas are treated with electrodesiccation (cauterization) and curettage (excision), though laser treatment using pulsed dye laser or CO laser is often effective.

Several reports have demonstrated the efficacy of topical application of the beta-adrenergic antagonist timolol in the treatment of pediatric pyogenic granuloma.

There is usually no treatment if the pyogenic granuloma occurs during pregnancy since the lesion may heal spontaneously. Recurrent bleeding in either oral or nasal lesions may necessitate excision and cauterization sooner, however. If aesthetics are a concern, then treatment may be pursued as well. Usually, only minor surgery may be needed, along with a dental cleaning for oral lesions to remove any calculus or other source of irritation. For nasal lesions, nose-picking should be discouraged.

Granuloma annulare, microscopically, consists of dermal epithelioid histiocytes around a central zone of mucin - a so-called palisaded granuloma.

The basis of management is to find and correct the underlying cause. Many times cats with EGC will respond to treatment with corticosteroids or to ciclosporin.

Overall, lick granulomas are very difficult to treat, with control only being achieved in about 65 percent of cases. Some animals will continue to lick at the area despite the use of anti-lick ointments or sprays to deter them, for instance.

Currently there is no cure for actinic prurigo, and treatment focuses on relieving the dermatologic symptoms, by way of topical steroid creams or systemic immunosuppressants.

Prescribed treatments include:

- topical creams such as Tacrolimus and Betamethasone.

- systemic immunosuppressants such as Prednisone.

- In some cases, Thalidomide has proven to be effective in controlling the symptoms of actinic prurigo.

All patients with AP are encouraged to minimize sun exposure, and to use strong sunscreen throughout the year, and even on cloudy or overcast days, as UVA light, unlike UVB light, is able to penetrate cloud cover and remains constant throughout the day.

Alternative treatment methods might include UV Hardening, Meditation and/or cognitive behavioral therapy. UV-A desensitization phototherapy has also been shown to be effective in cases.

In the earlier stages of actinic elastosis, elastic fiber proliferation can be seen in the dermis. As the condition becomes more established, the collagen fibers of the papillary dermis and reticular dermis become increasingly replaced by thickened and curled fibers that form tangled masses and appear basophilic under routine haematoxylin and eosin staining. These fibers stain black with the Verhoeff stain.

Numerous treatment options are available for photoaged skin, including dermabrasion, topical application of retinoic acid, carbon dioxide laser resurfacing, hyaluronic acid injection into the dermis, imiquimod, tacrolimus ointment, and topical oestrogen therapy. These treatments have variable efficacy.

The most effective prevention strategy for photoaging remains minimization of sun exposure, through use of sunscreen and other sun exposure avoidance measures.

Keratosis (from "keratinocyte", the prominent cell type in the epidermis, and , abnormal) is a growth of keratin on the skin or on mucous membranes. More specifically, it can refer to:

- actinic keratosis (also known as solar keratosis)

- hydrocarbon keratosis

- keratosis pilaris (KP, also known as follicular keratosis)

- seborrheic keratosis

Actinic keratoses are pre-malignant growths. Seborrheic keratoses are not pre-malignant.

To prevent AC from developing, protective measures could be undertaken such as avoiding mid-day sun, or use of a broad-brimmed hat, lip balm with anti UVA and UVB ingredients (e.g. para-aminobenzoic acid), or sun blocking agents (e.g. zinc oxide, titanium oxide) prior to sun exposure.

This condition is considered premalignant because it may lead to squamous cell carcinoma in about 10% of all cases. It is not possible to predict which cases will progress into SCC, so the current consensus is that all lesions should be treated.

Treatment options include 5-fluorouracil, imiquimod, scalpel vermillionectomy, chemical peel, electrosurgery, and carbon dioxide laser vaporization. These curative treatments attempt to destroy or remove the damaged epithelium. All methods are associated with some degree of pain, edema, and a relatively low rate of recurrence.

Treatment usually involves surgical removal of the lesion down to the bone. If there are any adjacent teeth, they are cleaned thoroughly with scaling and root planing (SRP) to remove any possible source of irritation. Recurrence is around 10%.

The lesion should also be treated.

Class 4 infrared laser treatments have been used with much success, although it may take several treatments to achieve the desired outcome.

Licking can be prevented by the use of Elizabethan collars, battery-enhanced wraps, bandages, anti-licking ointments (which are bad tasting), and anti-lick strips (which are either bad tasting or simply provide a barrier). It is important to catch lesions early and keep the animal from licking them to then reduce inflammation and development of a habit. Topical medications such as corticosteroids or DMSO may be effective if used early.

Small lesions may be injected with triamcinolone or methylprednisolone. Oral antibiotics are used to control infection. Surgery may be performed to remove whole lesions, but there is risk of continued self-mutilation to the area afterwards. Other potential treatments include cryosurgery, laser surgery, radiation therapy, and acupuncture. It is important to note that many dogs will lick at another leg, another area on the same leg, or someplace else, creating a new lick granuloma, if they are prevented from licking at the original one while it heals.

Annular elastolytic giant-cell granuloma (also known as "Giant cell elastophagocytosis," "Meischer's granuloma," "Miescher's granuloma of the face") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

The diagnosis is made clinically, and usually this is clear cut if the lesion is associated with the flange of a denture. Tissue biopsy is not usually indicated before removal of the lesion, since the excises surgical specimen is usually sent for histopathologic examination and the diagnosis is confirmed retrospectively. Rarely, incisional biopsy may be indicated to rule out neoplasia, e.g. in the presence of suspicious ulceration. The appearance may also be confused with pyogenic granuloma.

The excessive tissue is composed of cellular, inflamed fibrous connective tissue. The appearance of an epulis fissuratum microscopically is an overgrowth of cells from the fibrous connective tissue. The epithelial cells are usually hyperkeratotic and irregular, hyperplastic rete ridges are often seen.

AP is characterized by itchy, inflamed papules, nodules, and plaques on the skin. Lesions typically appear hours or days after exposure of the skin to UV light, and follow a general pattern of sun-exposed areas. The face, neck, arms, hands, and legs are often affected, although lesions sometimes appear on skin that is covered by clothing and thus not exposed to UV light, thus making AP somewhat difficult to diagnose.

AP is a chronic disease, and symptoms usually worsen in the spring and summer as the day lengthens and exposure to sunlight increases.

Eosinophilic granuloma is a form of Langerhans cell histiocytosis. It is a condition of both human and veterinary pathology. Colloquially, the reaction pattern is sometimes referred to as a rodent ulcer.

Feline eosinophilic granuloma complex is synonymous with "feline eosinophilic skin diseases". This is considered to be a cutaneous reaction pattern that can be the manifestation of a number of underlying infections, allergies or ectoparasite infestations. It can also be idiopathic, that is have no known underlying trigger. The eosinophilic reaction is common in feline inflammatory disease and the eosinophilic granuloma can be a hereditary reaction pattern in some lines of domestic cats.

Localized granuloma annulare has a tendency towards spontaneous resolution. Localized lesions have been treated with potent topical corticosteroids.

Fungal folliculitis (also known as Majocchi granuloma) is a skin condition characterized by a deep, pustular type of tinea circinata resembling a carbuncle or kerion.