Neurothekeoma | |
---|---|
Other names | Bizarre cutaneous neurofibroma, myxoma of nerve sheath, pacinian neurofibroma |
Neurothekeoma histology slide | |
Specialty | Oncology |
A Neurothekeoma (NT) is a type of rare benign cutaneous tumor that usually develops on the head and neck. They often occur in the second and early third decades of life and tend to afflict women more frequently than men.[1] First described by Richard L Gallager and Elson B. Helwig, who proposed the term in order to reflect the presumed origin of the lesion from nerve sheath.[2] Microscopically, the lesions described closely resembled the tumor, "nerve sheath myxoma (NSM)", an entity first described by Harkin and Reed.[3] The latter had, through the years, been variously described as bizarre cutaneous neurofibroma, myxoma of nerve sheath, and pacinian neurofibroma.[4]
Clinically, neurothekeomas present as a solitary nodule of the skin. The most common sites of occurrence are the head and neck and the extremities. The lesions range in size from about 0.5 cm to more than 3 cm. The average patient age is about 25 years, but neurothekeomas may occur at any age. Women are affected about twice often; the male to female ratio is approximately 1:2.[5]
Microscopically, neurothekeoma consists of closely aggregated bundles or fascicles of spindle-shaped cells. The fascicles may or may not have a myxoid background.[6]
Since the time of their first description, it has been reported that neurothekeomas are likely not of nerve sheath origin, as implied by the term.[5] Consequently, neurothekeoma and nerve sheath myxoma are likely not related histogenetically, although they are similar in appearance and in behavior.[5] Based mostly on the quantity of myxoid matrix present, neurothekeomas can have a variety of histologic characteristics, including myxoid, cellular, or mixed-type. The myxoid variety of neurothekeoma has inadvertently included nerve sheath myxoma because to similarity in clinical presentation and histology. However, it appears that the neurothekeoma that Barnhill and Mihm reported in 1990 is a separate and distinct entity from true nerve sheath myxoma.[7] It has been proposed that neurothekeomas are derived from fibrohistiocytic cells rather than the peripheral nerve sheath.[8][9][10][11] Despite having a different histologic appearance, neurothekeomas do not respond with the S100 protein while nerve sheath myxoma do (myxoid, mixed, or cellular).