Melanocytic nevus
Melanocytic nevus is a type of melanocytic tumor that contains nevus cells. The majority of nevi appear during the first two decades of a person's life. With about one in every 100 babies being born with nevi. Acquired nevi are a form of benign neoplasm, while congenital nevi are considered a minor malformation or hamartoma and may be at a higher risk for melanoma. Benign nevus are circular or oval and are usually small (commonly between 1–3 mm), though some can be larger than the size of a typical pencil eraser (5 mm). Some nevi have hair.

Laser surgery are commonly done to cosmetically remove small nevi. If the size is larger than 4-5 mm, surgical excision may be required. In young children, a nevus larger than 2 mm in size is often difficult to be completely removed without scarring.
#CO2 laser
#Er-YAG laser
  • Normal nevus
  • Becker nevus ― Shoulder; characterized by the growth of hair on the nevus.
  • Nevus of Ota ― Appears blue due to the deep location of nevus cells in the dermal layer. In this patient's case, the nevus is located on the conjunctiva. Ota nevus can be removed through laser treatment.
  • Compound nevus ― Buttock. Small birthmarks can grow to large nevi with age.
  • Intradermal nevus ― The shape of a protruding nodule.
  • Normal nevus. The two photographs below are intradermal nevus, and the three photographs above are junctional nevus.
  • Blue nevus ― Due to the deep location of nevus cells, it appears blue.
  • Intradermal nevus ― It is commonly observed on the scalp.
  • This picture indicates a nevus lesion. However, if the main lesion is small like this, the algorithm may not be able to accurately predict the condition.
References Effective Treatment of Congenital Melanocytic Nevus and Nevus Sebaceous Using the Pinhole Method with the Erbium-Doped Yttrium Aluminium Garnet Laser 25324667 
Congenital melanocytic nevus (CMN) is a melanocytic nevus that is either present at birth or appears during the latter stages of infancy. Nevus sebaceous has been described as the hamartomatous locus of an embryologically defective pilosebaceous unit. Here, we describe how we used the pinhole technique with an erbium-doped yttrium aluminium garnet (erbium : YAG) laser to treat nevi lesions in different patients.
 Malignant Melanoma 29262210 
A melanoma is a tumor produced by the malignant transformation of melanocytes. Melanocytes are derived from the neural crest; consequently, melanomas, although they usually occur on the skin, can arise in other locations where neural crest cells migrate, such as the gastrointestinal tract and brain. The five-year relative survival rate for patients with stage 0 melanoma is 97%, compared with about 10% for those with stage IV disease.