Benign skin lesions

Benign skin tumors are noncancerous skin growths and include hemangiomas, angiomas, angiokeratomas, seborrheic keratoses, dermatofibromas, lipomas, dermal cylindromas, acrochordons, epidermoid cysts, and sebaceous hyperplasia. Benign skin tumors are typically diagnosed based on the appearance of the lesion, but histology may be performed on a biopsy sample to rule out malignancy. Treatment is usually not necessary unless indicated for suspected malignancy, cosmetic reasons, or if symptoms are bothersome.

See also “Hypertrophic and keloid scars” and “Collection of dermatological disorders.”

Infantile hemangioma (strawberry hemangioma)

See “Strawberry hemangioma.”

Cherry hemangioma (Campbell de Morgan spots) ^[1]

• Epidemiology ^[2]
  • More common in adults > 30 years
  • Incidence increases with age (most common acquired cutaneous vascular anomaly)
• Pathophysiology: benign proliferation of dilated mature capillaries
• Etiology: unknown, genetic predisposition
• Clinical features
  • Bright cherry red, dome-shaped papules or macules that may appear purple with time (0.5–6 mm in diameter)
  • Usually on the trunk and upper extremities, but may occur all over the body
  • Usually multiple lesions
• Diagnosis: : based on clinical appearance of lesion
• Treatment
  • Intervention is not necessary unless bleeding occurs or for cosmetic reasons
  • Options: electrocauterization, vascular laser therapy
• Complications: profuse bleeding after trauma
• Prognosis
  • No malignant potential
  • No spontaneous regression
  • No prevention possible

Pyogenic granuloma ^[1][3]

• Definition: benign vascular tumor characterized by rapid growth and tendency to bleed easily
• Etiology
  • Cause unknown
  • Associated with trauma and pregnancy
• Clinical features
  • Soft, round, bright red tumor that bleeds easily
  • Polypoid and lobulated
  • Occasionally ulcerates
  • Localization: usually develops at a site of skin injury on the face or hands
• Diagnosis: based on clinical appearance of lesion and history of rapid growth and easily injured/bleeding surface
• Treatment: surgical excision

Angiomatosis ^[1][4][5]

• A rare vascular lesion, characterized by proliferation of vessels mixed with adipose tissue.
• May appear similar to hemangiomas or vascular malformations
• Typically benign

• Definition: hyperkeratosis and hyperplasia of epidermis commonly caused by human papillomavirus (HPV)
• Epidemiology: : more frequent in children and young adults
• Etiology
  • Common clinical manifestation of HPV
  • Transmitted by direct skin contact
• Clinical features
  • Common warts (verruca vulgaris)
    • Localization: elbows, knees, fingers, palms
    • Appearance: skin-colored or whitish, soft, rough-surfaced, scaly papules or plaques (sometimes with a cauliflower-like appearance)
  • Flat warts (verruca plana)
    • Localization: face, back of the hand, legs
    • Appearance: flesh-colored, smooth papules, flat surface
  • Plantar wart (verruca plantaris)
    • Localization: soles of the feet
    • Appearance: flesh-colored, hyperkeratotic surface
  • Anogenital warts: see “Anogenital warts.”
• Histology
  • Epidermal hyperplasia
  • Irregular hyperkeratosis
  • Koilocytes
  • Papillomatosis (i.e., elongated rete ridges of the epidermis that point towards the center of the wart)
  • Acanthosis
• Diagnosis: based on clinical appearance of lesion
• Treatment
  • Indications
    • Pain, functional impairment
    • Cosmetic reasons
    • Immunosuppression
  • Pharmacological treatment
    • First-line: salicylic acid (daily application for a few weeks)
    • Alternatives: 5-fluorouracil cream or topical retinoic acid for flat warts
  • Surgery
    • Cryotherapy with liquid nitrogen
    • Surgical excision
• Prognosis
  • Healthy children usually achieve spontaneous remission within 2 years.
  • Warts may recur and require multiple treatments.

• Definition: benign growths of immature keratinocytes ^[4][6]
• Epidemiology: most common benign skin tumor in the elderly population
• Etiology: incompletely understood
  • Genetic predisposition
  • Paraneoplastic seborrheic keratosis (Leser-Trélat sign) most commonly results from gastrointestinal cancer.
• Clinical features
  • Multiple darkly pigmented papules/plaques, sharply demarcated, and soft
  • Greasy, wax-like, and “stuck-on” appearance
  • May become irritated by external trauma or spontaneously
  • May be pruritic or bleed easily
  • Usually single lesion but can also appear as multiple seborrheic keratosis (Leser-Trélat sign)
  • Localization: trunk, back of the hands, forearms, head, face, and neck
• Diagnosis
  • Clinical diagnosis: Lesions are usually easily recognized.
  • If in doubt, a shave or excisional biopsy can be performed to rule out malignancy.
• Histopathology ^[7]
  • Papillomatosis
  • Proliferation of squamous epithelium
  • Immature keratinocytes with small keratin-filled cysts (horn cysts)
• Treatment
  • Not necessary
  • Cryotherapy, laser therapy, or surgical excision if desired for cosmetic reasons or if lesions become symptomatic

• Definition: fibroblast proliferation resulting in small, fibrous benign dermal growth ^[1][4]
• Epidemiology: ♀ > ♂
• Etiology: not fully understood (sometimes related to insect bites or trauma)
• Clinical features
  • Asymptomatic
  • Slowly growing, skin-colored or brownish nodules of ∼ 3–10 mm diameter
  • Localization: most common on lower extremities, but can appear anywhere on the body
• Diagnosis: dimple sign (Fitzpatrick sign): pinching of lesion produces central dimple (characteristic sign of dermatofibroma)
• Treatment
  • Usually no treatment required
  • Indications for excision: cosmetic reasons, symptomatic lesion, or suspicion of malignancy

• Definition: congenital or acquired usually highly pigmented area (benign neoplasm) on the skin that is either flat or raised (a mole)

Becker nevus (melanosis naeviformis) ^[4][6]

• Epidemiology: mostly in adult males (late-onset nevus)
• Etiology
  • ↑ Androgens
  • Exposure to sunlight
• Clinical features
  • Large hyperpigmented patch with hair (hypertrichosis)
  • Localization: shoulder, upper trunk
  • Becker nevus syndrome: Becker nevus may, in very rare cases, be associated with musculoskeletal malformations and ipsilateral under-development of the breasts in women.
• Diagnosis: skin biopsy to distinguish from malignant differential diagnoses
• Treatment: not required
• Prognosis: no malignant potential

Linear verrucous epidermal nevus

• Epidemiology: 1–3/1000 live births
• Etiology: sporadic, may be associated with other developmental abnormalities
• Clinical features
  • Hyperkeratosis and thickening of the epidermis
  • Skin-colored/brown verrucous papules (wart-like) that usually form a line
  • May coalesce to form patches along Blaschko lines that represent migration pathways of embryonic skin cells
  • Inflammatory linear verrucous epidermal nevus (ILVEN)
    • More widespread distribution of nevi on one side of the body
    • Usually accompanied by inflammation and pruritus
• Diagnosis
  • Based on clinical appearance
  • If diagnosis is in doubt, confirm with biopsy
• Treatment
  • Not required
  • May be excised for cosmetic reasons
• Prognosis: no malignant potential

Spitz nevus (spindle and epithelioid cell nevus) ^[4][6]

• Epidemiology: more common in children
• Etiology: : unknown (associated with pregnancy and puberty)
• Histology: irregular and spindle-shaped nevus cells
• Clinical features
  • Solitary, nodular nevus (may be difficult to distinguish from melanoma)
  • Well-circumscribed
  • Often rapidly growing
• Diagnosis: histopathology of excised nevus
• Treatment: Excision with histopathological confirmation is recommended.
• Prognosis: rarely malignant

Nevus spilus (speckled lentiginous nevus)

• Epidemiology: prevalence of ∼ 2%
• Etiology
  • Not fully understood
  • Environmental and genetic influences possible
• Clinical features
  • Congenital brownish or tan macule (comparable to café au lait spot)
  • Speckled with smaller darker spots
• Diagnosis
  • Based on clinical appearance
  • If diagnosis is in doubt, confirm with biopsy
• Treatment: usually not necessary
• Prognosis: benign, but melanoma may rarely arise in a nevus spilus

Common acquired melanocytic nevi (often referred to as “moles”) ^[4][6]

• Epidemiology: common, regardless of age, gender, or ethnicity
• Etiology
  • Genetics (parents with many moles)
  • Associated with light skin and red hair
  • Intense sun exposure during childhood
• Clinical features: In general, all types have a uniform color, border, and surface.
  • Junctional nevi: flat, well-demarcated brownish macules growing at the dermal-epidermal junction
  • Compound nevi: arising from a junctional nevus, forming an elevated lesion
  • Intradermal nevi: elevated papular lesion that may be hard (fibrotic) and grow hair
• Diagnosis: Dermoscopy shows well-nested melanocytic proliferations at the dermal-epidermal junction.
• Treatment
  • Usually not required
  • Biopsy or excision if nevi appear atypical
• Prognosis: dysplastic nevi (atypical moles) and congenital moles can undergo dysplastic changes → melanoma formation

Nevus sebaceous

• Epidemiology: onset commonly during childhood
• Etiology: unclear, probably due to gene mutations
• Clinical features:
  • Skin-colored, elevated lesion with surrounding alopecia
  • Localization: usually occurs as single lesion on scalp
• Diagnosis: based on clinical appearance
• Treatment: prophylactic excision if sebaceous nevus persists after puberty
• Prognosis
  • Usually regress after puberty
  • Risk of degeneration if persistent

Dysplastic nevus (atypical mole) ^[4][6]

• Epidemiology: 2–10% in White populations
• Etiology
  • Genetics (parents with many moles)
  • Associated with light skin
  • Intense sun exposure during childhood
• Clinical features
  • ABCDE criteria
  • Ugly duckling sign: Differences between nevi in the same patient should be considered suspicious.
• Diagnosis
  • Clinical diagnosis
  • Dermoscopy can be helpful in clarifying and distinguishing from melanoma.
• Treatment: excision of suspicious lesions
• Prognosis: risk of malignant melanoma if associated with dysplastic nevus syndrome

• Definition: common benign tumor of subcutaneous soft-tissue, made up of mature fat cells ^[1][4]
• Etiology: unknown, genetic predisposition
• Clinical features
  • Slow-growing round, soft, rubbery tumor (may be solitary or multiple)
  • Non-tender
  • Localization: typical locations are head, neck, shoulders, and back
• Special type: Lipomatosis is an autosomal-dominant disorder characterized by multiple lipomas.
• Diagnosis: clinical diagnosis
• Treatment
  • Usually not required
  • Surgical excision can be considered in the following cases:
    • If tumor causes pain
    • Cosmetic reasons
    • If tumor grows rapidly or is firm on palpation

• Definition: rare benign skin appendage tumors (formerly classified as apocrine in origin)
• Etiology: unknown
• Clinical features: may occur as a single tumor or as multiple tumors associated with Brooke-Spiegler syndrome (autosomal dominant familial cylindromatosis associated with cylindromas, trichoepitheliomas, and spiradenomas)Solid, skin-colored nodules
  • Involves the head, neck, and face
• Diagnosis: clinical diagnosis (based on clinical appearance of lesion)
• Treatment
  • Surgical excision
  • Electrodesiccation/curettage
  • Cryotherapy
• Prognosis: malignant transformation is very rare

• Definition: a benign disorder characterized by hyperpigmentation of the skin that is associated with pregnancy and oral contraceptive use
• Epidemiology
  • Common in dark-skinned individuals ^[8]
  • Incidence in ♀ > ♂
• Etiology
  • Pregnancy: referred to as “mask of pregnancy”
  • Hormonal contraceptives
  • Neoplastic diseases that produce hormones
• Clinical features
  • Hyperpigmented lesions on the face
  • Exacerbated by exposure to sunlight (UV radiation)
• Diagnosis: clinical diagnosis
• Treatment
  • Sunscreen
  • Topical depigmenting agents (e.g., hydroquinone)

• Definition: a condition characterized by velvety, hyperpigmented plaques on the skin that most frequently involve intertriginous sites such as the axillae and neck
• Etiology
  • Endocrinal
    • Diabetes mellitus type 2
    • PCOS
    • Cushing syndrome
  • Obesity: pseudoacanthosis nigricans
  • Familial causes: autosomal dominant inheritance
  • Drug-related causes (e.g., glucocorticoids, oral contraceptives)
• Pathogenesis: insulin, IGF, and/or other growth factors (e.g., fibroblast growth factor) → epidermal hyperplasia and fibroblast proliferation ^[9]
• Clinical findings
  • Brown to black, intertriginous and/or nuchal hyperpigmentation that can develop into itching, papillomatous, poorly defined eruption
  • Symmetrical thickening of skin
  • Localization: axilla, groin, neck
• Differential diagnosis: malignant acanthosis nigricans
• Treatment
  • No specific treatment available; primary aim is to treat the underlying condition
  • Cosmetic treatment involves laser therapy, dermabrasion, and topical retinoids.

• Definition: flat, brown macules or patches that are induced by sun exposure
• Epidemiology: usually seen in older fair-skinned people
• Etiology: exposure to ultraviolet (UV) radiation
• Pathophysiology: increase in the production of melanin, which is then deposited in basal keratinocytes
• Clinical features
  • Flat, brown macules or patches
  • Localization: most common on the cheeks and back of the hands
• Treatment: usually not necessary

• Definition: secondary skin lesions as a result of chronic scratching
• Clinical features
  • Lichenified plaques and excoriations
  • Lesions occur on any part of the body that is scratchable, including anogenital areas (e.g., vulva, scrotum, anus)
• Histopathology: hyperplasia and hyperkeratosis of squamous epithelium ^[10]
• Treatment
  • Treat the underlying cause of pruritus to avoid scratching
  • Topical corticosteroids
• Prognosis: benign condition (risk of squamous cell carcinoma not increased)

• Definition: small, sometimes slightly discolored, papillomatous skin lesions that most commonly arise in skin creases
• Epidemiology: prevalence is between 50% and 60% in individuals > 50 years of age and increases with age ^[11]
• Etiology
  • Not fully understood; thought to be caused by frequent irritation, e.g., skin rubbing on skin
  • Associated with HPV and endocrine changes; (e.g., during pregnancy, or in obesity, type 2 diabetes mellitus, and acromegaly)
  • Perianal acrochordons are associated with Crohn disease.
• Clinical features ; ^[11][12]
  • Typically arise in locations exposed to friction; (e.g., lower neck, axilla, inframammary fold, inguinal region)
  • Usually small, soft, sometimes slightly discolored, pedunculated outgrowths with a smooth surface
• Diagnostics: clinical diagnosis
• Histopathology: composed of hyperplastic epithelium and accumulations of collagen; usually well-vascularized
• Differential diagnoses: warts, seborrheic keratosis, neurofibromas, nevi, basal/squamous cell carcinoma
• Treatment
  • No intervention necessary; may be removed for cosmetic reasons
  • Removal methods include surgical excision (usually with fine-grade scissors), cryotherapy, and electrodesiccation.