Skin melanocytic tumor

Melanocytic neoplasms	ICD-O	ICD-11
Melanocytic neoplasms in intermittently sun exposed skin
Nevi
Junctional, compound and dermal nevi	8740/0, 8760/0, 8750/0	2F36.Y & XH1M79, XH27A6, XH2MQ5
Simple lentigo and lentiginous melanocytic nevus	8742/0	2F20.0Y, 2F20.2Y
Dysplastic nevus	8727/0	2F20.1 & XH9035, 2F72.2
Nevus spilus	8720/0	2F20.Y & XH40S8
Special site nevus (of the breast, axilla, scalp and ear)		2F20.1, 2F20.Y
Halo nevus	8723/0	2F20.Y & XH5971
Meyerson nevus	8720/0	2F20.Y & XH8NP4
Recurrent nevus		2F20.Y
Combined nevus	8720/0	2F20.Y & XH0DU8
Melanocytomas
WNT activated deep penetrating / plexiform melanocytoma (nevus)	8720/1	2F20.Y & XH81Y1
Pigmented epithelioid melanocytoma	8780/1	2F20.1 & XH4VD0
BAP1 inactivated melanocytoma	8720/1	2F20.1
MITF pathway activated melanocytic tumors	8727/0	2F20.1
Melanoma intermittently sun exposed skin
Melanoma on skin with low cumulative sun damage (low CSD); includes superficial spreading melanoma	8743/3	2C30.0
Melanocytic neoplasms in chronically sun exposed skin
Lentigo maligna melanoma	8742/3	2C30.2
Desmoplastic melanoma	8745/3	2C30.Y & XH1Z15
Spitz tumors
Spitz nevi
Pigmented spindle cell nevus (Reed nevus)	8770/0	2F20.Y & XH2P88
Spitz nevus	8770/0	2F20.Y & XH2HG8
Spitz melanocytoma
Spitz melanocytoma (atypical Spitz tumor)	8770/1	2F20.Y & XH9WF4, 2F72.1
Spitz melanoma	8770/3	2C30.Y & XH8DS3
Melanocytic tumors in acral skin
Acral nevi	8744/0	2F20.Y & XH9DB2
Acral melanoma	8744/3	2C30.3
Genital and mucosal melanocytic tumors
Mucosal and genital nevus
Melanosis		ED61.Y
Genital nevus	8720/0	2F20.Y & XH5EL4
Mucosal melanomas	8720/3	2C70.1, 2C11.2 & XH4846
Blue nevi and related tumors
Blue nevus and melanocytoses
Nevus of Ito and nevus of Ota		LC10
Congenital dermal melanocytosis		LC10
Blue nevus	8780	2F20.Y & XH7QJ7, XH3X84
Melanoma arising in blue nevus	8780/3	2C30.Y & XH1G74
Congenital melanocytic tumors
Congenital nevi
Congenital melanocytic nevus	8761/0	2F20.2Z
Proliferative nodules in congenital melanocytic nevus	8762/1	2F20.2 & XH6AH3
Melanomas arising in congenital nevi
Melanoma arising in giant congenital nevus	8761/3	2C30.Y & XH5L25
Ocular and central nervous system (CNS) melanocytic tumors
Conjunctival melanocytic tumors
Conjunctival nevus	8740/0, 8760/0, 8750/0	2F36.Y & XH1M79, XH27A6, XH2MQ5
Conjunctival melanocytic intraepithelial lesions	8720/2	2E63.1
Conjunctival melanoma	8720/3	2D00.0
Uveal melanocytic tumors
Uveal melanocytoma	8726/0	2F36.0
Uveal melanoma	8770/3, 8771/3, 8772/3, 8773/3, 8774/3	2D07.2, 2D06.4, 2D05.0
CNS melanocytic tumors
Diffuse meningeal melanocytic neoplasms: melanocytosis and melanomatosis	8728/0, 8728/3	2A01.0Y & XH8974, XH1BP7
Circumscribed meningeal melanocytic neoplasms: melanocytoma and melanoma	8728/1, 8720/3	2A01.0Y & XH2RY7, XH3DN1
Nodular, nevoid and metastatic melanomas
Nodular and other melanomas
Nodular melanoma	8721/3	2C30.1
Nevoid melanoma	8720/3	2C30.Y & XH8681
Dermal melanoma	8780/3	2C30.Y
Metastatic melanomas
Melanoma metastatic to the skin	8720/6	2E08 & XH4846
Melanoma metastatic to other organs	8720/6	2E0Y & XH4846

Contributed by Jonathan D. Ho, M.B.B.S., D.Sc.

What are melanocytic neoplasms with > 1 driver mutation with a second mutation affecting specific pathways resulting in distinct atypical microscopic features, increased risk of local recurrence and little risk of distant spread best defined as?

1. Melanocytic hyperplasia
2. Melanocytic tumors of uncertain metastatic potential
3. Melanocytomas
4. Melanomas
5. Nevi

C. Melanocytomas. Melanocytomas are neoplasms with > 1 driver mutation with a second mutation affecting specific pathways resulting in distinct atypical microscopic features and increased risk of local recurrence. Melanocytomas occur on a spectrum between nevi and melanoma. Examples include WNT activated deep penetrating / plexiform melanocytoma (previously deep penetrating nevus), pigmented epithelioid melanocytoma (PEM, also known as PRKAR1A inactivated melanocytoma) and BAP1 inactivated melanocytoma.

Answer D is incorrect because melanomas are malignant neoplasms that have accumulated mutations, allowing for unregulated growth and lack of response to tumor suppressor pathways. They have a risk of both local recurrence and distant metastasis. Answer E is incorrect because nevi are melanocytic tumors with a single initiating mutation, bland cytology and benign biology. Answer B is incorrect because melanocytic tumors of uncertain metastatic potential is reserved for neoplasms with atypical features that fall short of melanoma yet do not exhibit typical histopathologic, immunohistochemical and molecular features of well described melanocytomas. These are lesions with a prominent dermal component whose biologic behavior is unclear and in which melanoma is the main diagnostic consideration. Answer A is incorrect because melanocytic hyperplasia is a general term for an increase in epidermal melanocytes, which may be benign, atypical or frankly malignant.

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Reference: Skin melanocytic tumor - WHO classification