• Clinical science

Benign skin lesions


Benign skin lesions are non-cancerous skin growths that 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)
    • Epidemiology: incidence increases with age (most common acquired cutaneous vascular anomaly)
    • Pathophysiology: proliferation of dilated mature capillaries
    • Etiology: unknown, genetic predisposition
    • Clinical features
      • Bright cherry red, dome-shaped papules or macules → 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
  • Strawberry angioma: benign vascular tumor of infancy and childhood
  • Pyogenic granuloma
    • Definition: benign vascular tumor
    • Etiology: : cause unknown, associated with trauma and pregnancy
    • Clinical features
      • Soft, round, bright red tumor that bleeds easily
      • 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


Hypertrophic scars

  • Definition
  • Etiology: imbalance in wound healing processes due to various local and genetic factors
  • Clinical features
  • Diagnosis: : based on clinical appearance; of lesion and patient history of trauma or surgery
  • Treatment
  • Prevention: measures may be taken during surgery to avoid excessive scar formation (e.g., incisions should follow skin creases, reduced tension in closed wound)


Keloid scars

  • Definition
    • Skin lesions caused by high fibroblast proliferation and collagen production as excessive tissue response to typically small skin injuries
    • Grows beyond the boundaries of the original lesion
    • Does not regress spontaneously
    • Recurs after resection
  • Etiology: imbalance in wound healing processes due to local factors and genetics
  • Clinical features
    • Scar tissue of varying consistency (soft or hard) that may be brownish-red in color
    • 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)




Seborrheic keratosis

  • Definition: benign growths of immature keratinocytes
  • Epidemiology: most common benign skin tumor in the elderly population
  • Etiology
  • 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
    • Increase in number and size with time
    • Localization: trunk, back of the hands, face and neck, and forearms
  • Diagnosis: : Lesions are usually easily recognized; . If in doubt, a shave or excisional biopsy can be performed to rule out malignancy.
  • Histology
  • Treatment
    • Not necessary
    • Cryotherapy, laser therapy, or surgical excision if desired for cosmetic reasons or if lesions become symptomatic
  • Prognosis: secondary malignant tumors may arise (rare)



  • Definition: fibroblast proliferation resulting in small, fibrous benign dermal growth
  • Epidemiology: >
  • Etiology: sometimes related to insect bites or trauma, may have unknown cause
  • Clinical features
    • Asymptomatic
    • Slowly growing, skin-colored or brownish nodules of ∼ 3–10 mm diameter
    • Localization: most common on lower extremities; can be found anywhere on the body
  • Diagnosis: dimple sign; (Fitzpatrick's 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)
Type Mongolian spot Becker nevus Spitz nevus Common acquired melanocytic nevus Dysplastic nevus (atypical mole) Giant congenital melanocytic nevus
Patient group
  • Congenital
  • More common in children
  • Common, regardless of age, gender, or ethnicity
  • Northern European descent, light hair and freckles
  • Congenital
Clinical features
  • Blue-grey hyperpigmented macula, usually on the sacral-gluteal region
  • Non-tender and non-blanching
  • Harmless, usually disappears spontaneously during childhood
  • 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
  • Usually not required
  • Usually not required
  • Excision is recommended for histopathological confirmation.
  • Surgical excision or laser treatment

Becker nevus (melanosis naeviformis)

Spitz nevus (spindle and epithelioid cell nevus)

  • Epidemiology: more common in children
  • Etiology: : unknown; associated with pregnancy and puberty
  • Histology: : irregular and spindle-shaped nevus cells
  • Clinical features
    • Solitary, nodular nevus that 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

Common acquired melanocytic nevi (often referred to as “moles”)

  • Epidemiology: common, regardless of age, gender, or ethnicity
  • Etiology
    • Genetics (parents with many moles)
    • Fair skin and red hair
    • Intense sun exposure during childhood
  • Clinical features
    • Generally, 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 → 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

Dysplastic nevus (atypical mole)

  • Epidemiology: 2–10% in white populations
  • Etiology:
    • Genetics (parents with many moles)
    • Fair skin
    • Intense sun exposure during childhood
  • Clinical features
    • ABCDE criteria: Asymmetric shape, Border irregularities, Color inconsistency, Diameter enlarges (usually > 5 mm), Evolving lesion
    • Ugly duckling sign: Differences between nevi in the same patient should be considered suspicious.
  • Diagnosis: based on clinical appearance of lesion; dermoscopy 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
  • Etiology: unknown, genetic predisposition
  • Clinical features
    • Slow-growing round, soft “rubberytumor (may be solitary or multiple)
    • Non-tender
    • Localization: almost any subcutaneous region
  • Special type: Lipomatosis is an autosomal-dominant disorder characterized by multiple lipomas.
  • Diagnosis: clinical diagnosis
  • Treatment: usually not required; ; surgical excision; may be performed if tumor causes pain; or for cosmetic reasons; , or if the tumor grows rapidly; or is firm on palpation


Dermal cylindroma




Benign acanthosis nigricans

Solar lentigo (liver spots)

  • Definition: flat, brown macules or patches that are induced by sun exposure
  • Usually seen in older fair-skinned people (old age spots)
  • Results from an increase in the production of melanin, which is then deposited in basal keratinocytes
  • Most common on the cheeks and back of the hands

Lichen simplex chronicus