Gastric Plexiform Fibromyxoma

Excerpt

A 65-year-old male with past medical history of hypertension, hyperlipidemia, diabetes mellitus type 2, and adrenal cortical carcinoma presented to a local hospital for symptomatic anemia requiring multiple transfusions. After stabilization and discharge, the patient was referred to our institution for further evaluation and management of a suspected gastrointestinal stromal tumor (GIST). The patient reported 6 months of early satiety and worsening dyspepsia refractory to proton pump inhibitor therapy. Abdominal computed tomography (CT) showed a 5.0-cm mass in the stomach (Fig. 1a, b). He underwent esophagogastroduodenoscopy (EGD) and endoscopic ultrasound (EUS) revealing a 5.0 × 2.3 cm poorly defined, bilobar hypoechoic mass in the gastric antrum that arose from the muscularis propria (Fig. 1c, d). Immunohistochemistry (IHC) of the core needle biopsy revealed strongly positive staining for smooth muscle actin (SMA), weakly positive staining with CD117 (c-KIT), and patchy staining of Discovered on GIST-1 (DOG-1). The staining pattern was ambiguous between myxoid GIST and plexiform fibromyxoma. Shortly thereafter, the patient presented to the emergency room with hematemesis and anemia. After resuscitation including multiple units of packed red blood cells, ongoing bleeding was seen on upper endoscopy and the patient elected to undergo surgical treatment. Open gastric wedge resection was performed. The exophytic mass was removed from the lesser curve of the stomach and the defect was closed in a primary hand-sewn fashion (Fig. 1e, f). Final gross examination revealed a 5.0-cm smooth, pink, lobular mass and histopathology demonstrated a transmural myxoid bland spindle cell lesion with prominent thin capillaries (Fig. 2a, b). The mass had luminal ulceration and infiltrated the mucosa, submucosa, and muscularis propria. Final IHC stains where positive for SMA and negative for S-100, MUC-4, CD117, and DOG-1 (Fig. 2c, d). Pathology was most consistent with plexiform fibromyxoma, and not a GIST.

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