Isolated Malignant Peripheral Nerve Sheath Tumor of the Scalp

Surgical Treatment of Malignant Peripheral Nerve Sheath Tumor of the Scalp With Intracranial and Extracranial Extension: A Rare Case Report

ABSTRACT

Malignant peripheral nerve sheath tumors of the scalp are rare neoplasms of the peripheral nervous system. Here, we describe an unusual malignant peripheral nerve sheath tumor of the scalp in an 84-year-old Asian man. The tumor was associated with bony destruction, intracranial, and extracranial extension. Trans-arterial embolization was done twice preoperatively. En block excision was performed and the dura and soft tissue defect were reconstructed by anterolateral thigh free fasciocutaneous flap. There is no recurrence and the wound healed well during follow-up.

Mosaicism in Tumor Suppressor Gene Syndromes: Prevalence, Diagnostic Strategies, and Transmission Risk

A mosaic state arises when pathogenic variants are acquired in certain cell lineages during postzygotic development, and mosaic individuals may present with a generalized or localized phenotype. Here, we review the current state of knowledge regarding mosaicism for eight common tumor suppressor genes-NF1, NF2, TSC1, TSC2, PTEN, VHL, RB1, and TP53-and their related genetic syndromes/entities. We compare and discuss approaches for comprehensive diagnostic genetic testing, the spectrum of variant allele frequency, and disease severity. We also review affected individuals who have no mutation identified after conventional genetic analysis, as well as genotype-phenotype correlations and transmission risk for each tumor suppressor gene in full heterozygous and mosaic patients. This review provides new insight into similarities as well as marked differences regarding the appreciation of mosaicism in these tumor suppressor syndromes.