Neurothekeoma

Excerpt

Neurothekeomas are rare, benign, superficial soft tissue tumors that most commonly occur on the head and neck. They tend to affect females more often than males, usually in the second and early third decades of life. Neurothekeoma clinically presents as a skin-colored, pink, red, or brown well-circumscribed papule or nodule. Usually, they are asymptomatic but may be accompanied by pain with pressure. Neurothekeomas have variable histologic patterns, including myxoid, cellular, or mixed-type based primarily on the amount of myxoid matrix present. Because of overlapping clinical presentation and histology, nerve sheath myxoma has been inadvertently included within the myxoid variant of neurothekeoma. However, neurothekeoma as described by Barnhill and Mihm in 1990, appears to be a separate and distinct entity from true nerve sheath myxoma. Rather than arising from peripheral nerve sheath, it has been postulated that neurothekeomas are of fibrohistiocytic derivation. While nerve sheath myxoma demonstrates immunoreactivity for S100 protein, neurothekeoma fails to react with S100 regardless of the histologic pattern (myxoid, mixed, or cellular).