Myxoid Solitary Fibrous Tumor of the Vulva: A Diagnostic Pitfall.
Ahmet Erbağci, Abdullah Aydin, Filiz Özen et al.
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Case in brief
A 35-year-old woman presented with a slowly enlarging vulvar mass that imaging suggested was a benign cystic lesion. Histology instead showed a predominantly myxoid spindle-cell tumor, with staghorn-shaped vessels at the periphery. Diffuse nuclear STAT6 and CD34 positivity on immunohistochemistry, together with molecular confirmation of a NAB2:::STAT6 fusion, established the diagnosis of myxoid solitary fibrous tumor. The report does not describe treatment or clinical outcome.
What made this case unusual
Extensive myxoid change gave this vulvar solitary fibrous tumor atypical imaging and histologic features, creating a diagnostic pitfall: it was interpreted radiologically as a benign cystic lesion.
Diagnostic / clinical pearl
In a myxoid vulvar spindle-cell tumor, morphology and imaging may be misleading; diffuse nuclear STAT6 and CD34 staining, with molecular confirmation of NAB2:::STAT6 fusion, supported the diagnosis.