SMA-negative uninodular plexiform fibromyxoma: Case Report of a challenging atypical presentation of a rare gastric mesenchymal tumor in a 25-year-old female

Plexiform fibromyxoma (PFM) is an uncommon, benign mesenchymal tumor typically arising in the gastric antrum and usually characterized by a multinodular, plexiform growth pattern of smooth muscle actin (SMA)-expressing myofibroblastic-like cells. Rare variants with uninodular architecture and absence of SMA expression pose significant diagnostic challenges, as they may mimic gastrointestinal stromal tumors and require comprehensive histopathologic, immunohistochemical, and molecular evaluation to avoid misdiagnosis and inappropriate therapy.