• Clinical science

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.

Vascular skin tumors

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 [3][1]

  • 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

Other benign skin lesions [4][1][5]

Hypertrophic scars

  • 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
  • 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
  • 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

Keloid scars

  • 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 types I and III 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


Seborrheic keratosis

  • Definition: benign growths of immature keratinocytes [6][4]
  • Epidemiology: most common benign skin tumor in the elderly population
  • Etiology: incompletely understood
  • 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]
  • 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)
Overview of different nevi
Type Mongolian spot Becker nevus Spitz nevus Common acquired melanocytic nevus Dysplastic nevus (atypical mole) Giant congenital melanocytic nevus
Patient group
  • Congenital
  • Most common in adult males (late-onset nevus)
  • More common in children
  • Common, regardless of age, gender, or ethnicity
  • Northern European descent, light hair and freckles
  • Congenital
Clinical features
  • Blue-gray hyperpigmented macula, usually on the sacral-gluteal region
  • Non-tender and non-blanching
  • Rapidly growing solitary, nodular nevus
  • Junctional nevi
  • Compound or intradermal nevi
  • Light to darkly pigmented lesion, often with increased hair growth
Malignant potential
  • None
  • None
  • Possible (Rare)
  • Possible
  • Certain malignant change if associated with dysplastic malignant syndrome
  • Possible
  • Not required (usually disappears spontaneously during childhood)
  • Usually not required
  • Excision is recommended for histopathological confirmation.
  • Surgical excision or laser treatment

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

Linear verrucous epidermal nevus

  • Epidemiology: 1–3/1000 live births
  • Etiology: sporadic, may be associated with other developmental abnormalities
  • Clinical features
  • 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) [6][4]

  • 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
  • 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”) [6][4]

  • 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.
  • 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) [6][4]


  • Definition: commonbenign tumor of subcutaneous soft-tissue, made up of mature fat cells [4][1]
  • Etiology: unknown, genetic predisposition
  • Clinical features
    • Slow-growing round, soft “rubberytumor (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

Dermal cylindroma

  • 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


Benign acanthosis nigricans

Solar lentigo (liver spots)

  • 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

Lichen simplex chronicus