[Schwannoma, Neurofibromatosis Type 2, and Schwannomatosis in the 2021 WHO Classification of Tumors of the Central Nervous System].

Schwannomas are benign capsular tumors originating from Schwann cells. Although the majority are sporadic, they also occur within tumor predisposition syndromes, such as neurofibromatosis type 2, schwannomatosis, and Carney complex. Since the 5th edition of the World Health Organization(WHO)Classification of Tumors of the Central Nervous System was published, the description of grades has changed from Roman numerals to Arabic numerals. However, as in the 4th edition, it is still a WHO grade 1 benign tumor. There are several other subtypes of schwannomas in addition to the conventional type, and five subtypes have been specifically described in the 5th edition. "Melanocytic Schwannoma" in the 4th edition is now called "malignant melanotic nerve sheath tumor" in the 5th edition and is classified as a different tumor from schwannoma. Although the 5th edition places greater emphasis on genetic diagnoses, it is not essential for diagnosing schwannomas, and histological and clinical diagnoses remain equally crucial. Furthermore, after publication of the 5th edition in September 2022, an international consensus group renamed "neurofibromatosis type 2" as "NF2-related schwannomatosis." This article describes the shifts between the 4th to the 5th edition of the WHO Classification of Tumors of the Central Nervous System, along with additional clarifications, and offers the latest insights into treatment modalities for schwannomas and NF2.