Solitary Fibrous Tumor of the Adrenal Gland: A Comprehensive Review

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms characterized by a broad spectrum of anatomical localizations and variable biological behavior. Although initially described in the pleura, they can arise almost ubiquitously, including in endocrine glands. Nevertheless, adrenal involvement represents an exceptionally rare localization. Most adrenal SFTs (ASFTs) are non-functioning tumors detected incidentally. Radiological findings are generally non-specific or indeterminate and may overlap with those of other adrenal neoplasms, including malignancy, often leading to surgical resection to achieve pathological characterization. Definitive diagnosis relies on histopathological evaluation, where nuclear STAT6 expression—reflecting the pathognomonic NAB2–STAT6 gene fusion—serves as the diagnostic gold standard. Complete surgical resection is considered the treatment of choice. Although most ASFTs appear to have an indolent course, their biological behavior remains unpredictable, and long-term follow-up is advisable.