One of the less common but more challenging issues is ulceration of the skin or pyoderma gangrenosum (PG). Although PG was initially thought to be associated with Crohn’s or inflammatory bowel disease, it is now also known to be associated with malignancies, blood dyscrasias, diabetes, and hepatitis. Pyoderma has been described in several forms, but the ulcerative presentation usually occurs on the abdomen, perineum, and lower extremities. The lesions begin as discrete pustules that erupt and coalesce into a classic painful ulcer with a violaceous border and undermined edge. Multiple lesions are common.
PG is a significant complication associated with prolonged pain and increased morbidity.
As its aetiology and pathophysiology are poorly understood, multiple treatments have been employed. These include multiple topical therapies and corticosteroids given topically, intralesionally, or orally. Cyclosporin has also been tried, but Fauld and associates noted weak evidence for its use in pyoderma gangrenosum.
Peristomal pyoderma presents challenges to successful pouching. The size of the ulceration and its proximity to the stoma affects the seal of the appliance to the skin. The goal for management is to promote healing while maintaining adequate wear time of the pouch. The painful nature of PG ulcerations influences the options for topical care. Small ulcerations can usually be treated with stoma powder or antimicrobial powder covered by a piece of hydrocolloid. A foam dressing over the ulceration is helpful if the ulcer is particularly moist. Silver dressings in sheet form or calcium alginates have also been effective. The goal of topical therapy is to use a modality that can absorb the moisture and allow for appliance adhesion.

Lesions bearing normal dermal appendages and regular borders are likely to be benign pigmented naevi. Therefore diagnostic and not radical excision is indicated. Incision biopsy should not be done.

Melanocytic naevi are pigmented moles. Some moles are present at birth or appear within the first two years of life. These are known as congenital melanocytic naevi. Most develop during childhood and early adult life and are, consequently, called acquired melanocytic naevi. The number of moles increase up to the age of 30–40. Thereafter, the number of naevi tend to decrease. New moles appearing in adulthood need to be monitored and checked if growing or changing. Moles can be found anywhere on the skin, including on the hands and feet, genitals, eyes, and scalp.

There are three main types of acquired melanocytic naevi:
1. Junctional melanocytic naevi: flat and usually circular.
2. Compound melanocytic naevi: raised brown bumps most of which are hairy, some have a slightly warty surface.
3. Intradermal melanocytic naevi: raised and often hairy bumps, similar to compound naevi but more pale coloured (often skin-coloured).

Dermatofibromas may be pigmented and are often larger than they appear. They frequently occur at the sites of previous trauma.

Dermatofibromas are small, noncancerous (benign) skin growths that can develop anywhere on the body but most often appear on the lower legs, upper arms, or upper back. These nodules are common in adults but are rare in children. They can be pink, grey, red, or brown in colour and may change colour over the years. They are firm and often feel like a stone under the skin. When pinched from the sides, the top of the growth may dimple inward. These lesions feel larger than they appear visually.

Dermatofibromas are usually painless, but some people experience tenderness or itching. Most often, a single nodule develops, but some can develop numerous dermatofibromas.

Pilar or Trichilemmal cysts are common dermal cysts. They occur in less than 10% of the population. Of all skin cysts, Pilar cysts are the most common cysts. Pilar cysts usually occur in areas with dense hair follicle so that they are most commonly seen on the head especially the scalp, but they can also be found on the face, head, and neck.
Trichilemmal cysts never give rise to malignant lesions. They are usually sporadic. The cysts contain keratin and are outlined by stratified squamous epithelium similar to what we see in the outer(external) root sheath of the hair follicle. Proliferating trichilemmal cysts are the tumour form of pilar cysts, and it would appear in less than 3% of all cases of pilar cysts, and it might ulcerate and may be locally aggressive.

Pilar cysts are lined by thick capsules containing small layers of cuboidal, dark-staining basal epithelial cells in a palisade arrangement without an obvious intercellular gap. Those cells coalesce with multiple layers of keratinocytes forming squamous epithelium; these cells showed more maturation with dense eosinophilic-staining keratin in the absence of a granular cell layer. Sometimes we might see some areas of calcifications. Keratin in the pilar cysts stains with antikeratin antibodies similar to that seen in keratin derived from human hair. Trichilemmal cysts might rupture and of their components will leak into the dermis leading to the formation of foreign-body reaction.
Trichilemmal cysts are usually asymptomatic unless they calcify or rupture their contents leading to inflammatory process and pain in the affected site. Sometimes, the presence of pilar cyst overpressure or bony prominence might lead to pain. Trichilemmal cysts usually present as flesh-coloured, smooth, mobile, firm, and well-circumscribed nodules. Family history is very important since this condition can have an autosomal dominant pattern of inheritance. Usually, they are slow-growing nodules but sometimes they increase in size rapidly and it would indicate infection or malignant transformation. Young females are affected more than males.

Epidermoid cysts represent the most common cutaneous cysts. While they may occur anywhere on the body, they occur most frequently on the face, scalp, neck, and trunk.
Because most lesions originate from the follicular infundibulum, the more general term epidermoid cyst is favoured. The term sebaceous cyst should be avoided because it implies that the cyst is of sebaceous origin.
Epidermoid cysts are usually asymptomatic. Discharge of a foul-smelling “cheese like” material may be described. Less frequently, the cysts can become inflamed or infected, resulting in pain and tenderness. In the uncommon event of malignancy, rapid growth, friability, and bleeding may be reported.
Epidermoid cysts appear as flesh–coloured-to-yellowish, firm, round nodules of variable size. A central pore or punctum may be present.
Certain hereditary syndromes are associated with epidermoid cysts. Such syndromes include Gardner syndrome, basal cell nevus syndrome, and pachyonychia congenita. In addition, idiopathic scrotal calcinosis may actually represent an end-stage of dystrophic calcification of epidermoid cysts.
Epidermoid cysts may be removed via simple excision or incision with removal of the cyst and cyst wall through the surgical defect. If the entire cyst wall is not removed, the lesion may recur. Excision with punch biopsy technique may be used if the size of the lesion permits. Minimal-incision surgery, with reduced scarring, has been reported. An intraoral approach has been used to minimize facial scarring.
Incision and drainage may be performed if a cyst is inflamed. Injection of triamcinolone into the tissue surrounding the inflamed cyst results in a faster improvement in symptoms. This may facilitate the clearing of infection; however, it does not eradicate the cyst.

Pyogenic granuloma is a vascular lesion that occurs on both mucosa and skin, and appears as an overgrowth of tissue due to irritation, physical trauma, or hormonal factors. It is often found to involve the gums, the skin and nasal septum, and has also been found far from the head such as in the thigh. Contact bleeding and ulceration are common.

The correct treatment for an infected sebaceous cyst is incision and drainage with removal of the cyst wall. Conservation of the cyst wall invariably leads to recurrence. Furthermore, the infected wound must not be primarily closed. The administration of antibiotics without drainage of sepsis is futile.

A sebaceous cyst is a rounded swollen area of the skin formed by an abnormal sac of retained excretion (sebum) from the sebaceous follicles. It can occur anywhere but is most commonly formed on scalp, ears, back, face, and upper arm (not on palms of the hands and soles of the feet). The correct treatment for an infected sebaceous cyst is incision and drainage with removal of the cyst wall. Excision of the cyst wall needs to be complete to prevent recurrence.

Cock’s peculiar tumour is a suppurating and ulcerated sebaceous cyst, which may resemble a squamous cell carcinoma.

This may be a case of malignant melanoma. Excision biopsy is required to allow accurate histological assessment. If the diagnosis is confirmed, re-excision of margins may be required. Incisional or punch biopsy of lesions suspected to be melanoma is avoided.

Various options used for the treatment of skin lesions include:
1. Trucut biopsy
2. Punch biopsy
3. Excision biopsy
4. Wide excision biopsy
5. Incisional biopsy

Pyogenic granuloma (lobular capillary haemangioma) is a relatively common benign vascular lesion of the skin and mucosa whose exact cause is unknown
The name pyogenic granuloma is a misnomer since the condition is not associated with pus and does not represent a granuloma histologically. Pyogenic granuloma of the oral cavity is known to involve the gingiva commonly. Extragingivally, it can occur on the lips, tongue, buccal mucosa, palate, and the like. A history of trauma is common in such sites. The aetiology of the lesion is not known, though it was originally believed to be a botryomycotic infection. It is theorized that pyogenic granuloma possibly originates as a response of tissues to minor trauma and/or chronic irritation, thus opening a pathway for the invasion of nonspecific microorganisms, although microorganisms are seldom demonstrated within the lesion. Pathogenesis of pyogenic granuloma is still debatable.
Patients with pyogenic granuloma may report a painless glistening red lesion that bleeds spontaneously or after irritation.