Melanocytic nevus - 黑素細胞痣 https://en.wikipedia.org/wiki/Nevus
黑素細胞痣 (Melanocytic nevus) 是由黑色素細胞組成、含有痣細胞的腫瘤。大多數痣出現在人生的前二十年,約每 100 名新生兒中就有一人天生有痣。後天性痣屬於良性腫瘤;先天性痣則被視為輕度畸形或錯構瘤,且其黑色素瘤風險較高。良性痣多為圓形或橢圓形,直徑通常在 1–3 mm;少數可達約 5 mm(相當於普通鉛筆橡皮擦的大小)。有些痣上會長毛。

治療
雷射治療常用於美容性去除小痣。若直徑超過 4–5 mm,通常需要外科切除。對於幼兒而言,直徑超過 2 mm 的痣往往難以在不留下疤痕的情況下完全去除。
#CO2 laser
#Er-YAG laser
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References Effective Treatment of Congenital Melanocytic Nevus and Nevus Sebaceous Using the Pinhole Method with the Erbium-Doped Yttrium Aluminium Garnet Laser 25324667 
NIH
Congenital melanocytic nevus 是一種黑色素細胞痣,可能於出生時即出現,亦或在嬰兒期後期才顯現。皮脂腺痣被描述為胚胎發育缺陷所致的毛囊皮脂腺單位錯構瘤。以下說明我們如何運用針孔技術及 Erbium:YAG 雷射,治療不同患者的痣病變。
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 
NIH
黑色素瘤是一種腫瘤,當黑色素細胞(負責膚色的細胞)癌變時形成。黑色素細胞起源於神經嵴,這意味著黑色素瘤不僅可以在皮膚上生長,還可以在神經嵴細胞遷移的其他區域(例如胃腸道和大腦)中出現。早期黑色素瘤(0期)患者的存活率高達97%,而晚期(IV期)患者的存活率則大幅下降至約10%。
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.