Tumours of the Skin

Acquired Melanocytic Nevi Acquired nevi are lesions that appear after birth and consist of aggregates of apparently normal melanocytes. The two distinct periods during which nevi arise are from two to three years and at puberty; but nevi may arise at any age. Junctional Nevi: These are smooth, hairless, light to dark brown macules. They can be slightly elevated. They are usually multiple and can occur on any part of the body. Histologically the nests of melanocytes are confined to the dermo-epidermal junction.
Figure 1 High power view of an even tan 2mm macule on the forearm. The magnification exaggerates border irregularity.	Figure 2 Multiple tan macules on the back of a person being evaluated because of a family history of melanoma. The lesions are macular.
Intradermal Nevi: These are the common skin-colored moles found most often on the scalp, hand, and neck of adults. They are usually dome-shaped. Histologically the nests of melanocytes are confined to the dermis.
Figure 3 Elevated and partially pigmented lesion on the chin.	Figure 4 Slightly elevated brown papule.
Compound Nevi: These are the common raised and pigmented moles, often present on the face or trunk. The color varies from barely tan to dark brown. They are usually dome-shaped papules, but may become pedunculated. Histologically, the nests of melanocytes are both at the dermo-epidermal junction and in the underlying dermis.
Figure 5 Skin colored papule in the facial region.	Figure 6 Skin colored papule on the forehead.
Halo Nevi These are the pigmented nevi that develop a ring of peripheral depigmentation. The halo surrounding benign nevi are generally symmetrical, forming an almost perfect circle. With time, the central pigmented nevus will involute. Blue Nevi Blue Nevi are benign congenital or spontaneous appearing dermal nests of melanocytes which present as striking blue-gray or blue nodules. Common locations for these are on the head, neck, forearm, and dorsum of the hand. Congenital Melanocytic Nevi These are reported to occur in 2.5 percent of neonates. The small congenital nevi usually begin as flat, pale, tan macules which with time darken and develop irregularity of pigmentation, elevation and/or dark coarse hairs.
Figure 7 The cobblestone surface is typical for a mature congenital nevus. This lesion is on the shoulder of a medical resident.	Figure 8 This large irregular lesion, present since birth, was on the back of a young adult.
Giant Hairy Nevi These are present at birth as large continuous areas of multiple discrete patches of pigment often verrucous, often extremely hairy, cosmetically deforming lesions. Giant congenital pigmented nevi may eventually develop melanoma with an incidence of 15%. The incidence of melanoma in the smaller congenital nevi is unknown. In general, if a congenital nevus is small and can be excised with an acceptable cosmetic result, surgical excision is recommended. The larger melanoma prone lesions should be surgically excised and the defect repaired by skin grafting.
Figure 9 This is a typical halo nevus. Found on the back of a child, the biopsy proved the lesion to be benign.	Figure 10 Partially resected giant congenital nevus. These lesions may develop melanoma, hence the drastic surgery.
When should you biopsy a pigmented lesion? In many cases, patients ask the physician to evaluate a pigmented lesions because of fear of malignancy. The physician must decide whether or not a biopsy is warranted. Any pigmented lesion which exhibits one or all of the warning signs should be investigated:
Warning Signs Irregular border Irrigular distribution of pigment Onset after age 40 Change in size Change in color Pain, irritation, pruritus Infection Bleeding ulceration, crusting
In addition, many patients request examination of pigmented lesions for cosmetic reasons as well as fear of malignancy. Excisional biopsy followed by histopathological examination is frequently the appropriate procedure. No melanocytic lesions should be removed or destroyed without histopathological confirmation of its benignancy. In any case, when the diagnosis of benign melanocytic nevus is in doubt, surgical excision is the procedure of choice. Dermatofibroma Dermatofibromas are relatively common nodules which may appear on any part of the body surface, but most commonly on the legs. They are dark brown, red, or yellowish nodules which are fixed to the skin surface and freely moveable over the subcutaneous tissue. Lateral compression produces the characteristic dimple sign. The etiology has been assumed to be traumatic. These lesions may regress leaving an area of hypopigmentation. No treatment is necessary.
Figure 11 Here is a firm nodule, found on the leg of an otherwise well adult. Biopsy demonstrated swirls of thin collagen consistent with dermatofibroma.	Figure 12 Another dermatofibroma, this on the thigh. These lesions are characteristically firm to palpation and within the dermis.
Seborrheic Keratosis Seborrheic keratoses are benign epidermal tumors occurring after the age of 30 to 40 years. They have been considered as delayed epithelial nevi. They may occur on any part of the body but have a predilection for the trunk, shoulder, face, and scalp. They begin as small, thin, sharply circumscribed, smooth, light yellow or tan plaques and with time increase in thickness and develop a greasy crust. Examination of a lesion with a hand lens will demonstrate numerous keratin filled follicular openings scattered over the surface. Typical lesions appear superficial and characteristically have a "stuck-on" appearance. Occasionally traumatized lesions may become inflamed and present some difficulty in the differential diagnosis. Treatment is usually not necessary in those lesions in which the diagnosis is in doubt. Surgical excision is the treatment of choice. Cosmetic removal may be achieved by a light curettage electrodesiccation alone or a combination of the two. An excellent cosmetic result may also be obtained with liquid nitrogen or carbon dioxide freezing.
Figure 13 This typical seborrheic keratosis is exophytic and has multiple keratin pearls.	Figure 14 Another seborrheic keratosis which has been moistened with alcohol to demonstrate the multiple keratin pearls.
Capillary Hemangioma of Infancy This is characteristically a polyploid raised, bright red to deep purple lesions involving the dermis and subcutaneous tissue which is present at or appears shortly after birth. It occurs most commonly on the head. It may grow rapidly, achieving a large size. Although this hemangioma may be complicated by ulceration and infection, spontaneous involution usually occurs at age two to three years resulting in normal skin over a few telangiectatic vessels with wrinkled skin. Most of these lesions should be allowed to involute spontaneously; but if a capillary hemangioma has a possibility of interfering with vital processes it can be treated with systemic corticosteroids. Other modalities of therapy have been used but in general they produced less cosmetic or functional results than might have resulted from spontaneous involution.
Figure 15 This capillary hemangioma of infancy involves the tip of the nose and the upper lip.	Figure 16 Multiple capillary hemangiomas were present at birth in this infant who also had hemangiomas involving the liver.
Cherry Hemangiomas These red or purple papules occur predominantly on the trunk of middle aged and older patients. They are not easily compressed. Histologically they are capillary hemangiomas. If treatment is desired for cosmetic reasons superficial electrodesiccation may be used.
Figure 17 Here is a typical cherry hemangioma, seen at high magnification.	Figure 18 This cherry hemangioma became pedunculated and is now darker because of pending infarction.
Pyogenic Granuloma This is a localized superficial, often ulcerated, polyploid lesion, most commonly found on the extremities or face. It presents as a bright red to red-brown vascular tumor which tends to undergo necrosis. It is not readily compressed. It may bleed after a slight injury. Multiple pyogenic granulomas may occur especially during pregnancy. Untreated, a pyogenic granuloma may spontaneously regress. It may present a problem in differential diagnosis. Treatment may be by surgical excision or electrodesiccation.
Figure 19 This pregnant woman was evaluated for a rapidly growing tumor on her back.	Figure 20 Closer view of this lesion demonstrates the typical appearance of a pyogenic granuloma.
Spider Ectasia This is an arterial lesion characterized by a central punctum, which may pulsate, and radiate dilated branches. It may be congenital or acquired. Spider ectasias are especially common during pregnancy and with liver disease. Treatment is usually unnecessary. If desired, they can be blanched by light electrocoagulation of the central vessel.
Figure 21 Here is a close view of a typical spider ectasia. Pressure on this lesion would demonstrate filling from the center.	Figure 22 Multiple spider etasias such as these are usually associated with liver disease or pregnancy.