Benign skin lesions

Benign skin lesions are non-cancerous skin growths that may be pointed out by the patient or discovered during routine skin examinations. Accurately diagnosing a benign skin lesion and distinguishing it from a malignant condition requires consideration of the physical and histological characteristics of the lesion as well as the patient's attributes and overall condition. Biopsy or surgical excision is commonly performed when a potential malignancy cannot be ruled out. Treatment may be considered for cosmetic purposes.

Some of the most common benign skin lesions are covered in this card: hemangiomas, hypertrophic scars, keloid scars, warts, seborrheic keratosis, dermatofibromas, nevi, pyogenic granulomas, and lipomas.

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: cutaneous condition characterized by high fibroblast proliferation and collagen production that leads to a raised scar that does not grow beyond the boundaries of the original lesion
• Epidemiology: seen in individuals of all races, and should not be confused with keloid scars, which are more common in dark-skinned individuals
• Etiology: imbalance in wound healing processes due to various local and genetic factors
• Pathophysiology
  • Increased synthesis and parallel deposition of collagen type III
  • Increased expression of TGF-β
• Clinical features
  • Raised scar that does not grow beyond the boundaries of the original lesion, possibly erythematous (may be firm)
  • Pruritus
• Diagnosis: : based on clinical appearance of lesion and patient history of trauma or surgery
• Treatment
  • Medical therapy
    • First-line treatment: intralesional steroid injection → ↓ scar thickening, and relieves pain and pruritus, if present
    • Silicone gel sheets
    • Compression therapy
  • Surgery
    • Cryotherapy
    • Laser treatment
    • Surgical excision (may be combined with radiotherapy)
    • Light therapy
• Prevention: follow surgical principles associated with decreased risk of scar development (e.g., incisions should follow skin creases to reduce tension on the suture)
• Prognosis
  • Regresses spontaneously
  • Recurrences are infrequent

• Definition: skin lesions caused by high fibroblast proliferation and collagen production as excessive tissue response to, typically small, skin injuries
• Epidemiology: increased incidence in patients with a family history of keloids and in dark-skinned individuals
• Etiology: imbalance in wound healing processes due to local factors and genetics
• Pathophysiology
  • Increased synthesis and unorganized deposition of collagen type I and collagen type III
  • Increased TGF-β expression and fibroblast proliferation
• Clinical features
  • Brownish-red scar tissue of varying consistency (soft or hard) with claw-like appearance that grows beyond the boundaries of the original lesion
  • Pruritus
  • Pain
  • Localization: earlobes, face (especially cheeks), upper extremities, chest, and neck
• Diagnosis: : based on clinical appearance of lesion and patient history of trauma or surgery
• Treatment: same as for hypertrophic scars (see above)
• Prognosis
  • Does not regress spontaneously
  • Frequent recurrences after resection

• 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 fair 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 fair 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.