Gastric GIST with life-threatening anaemia and paraganglioma: a rare presentation of suspected Carney-Stratakis syndrome in a young adult.

Gastrointestinal stromal tumours (GISTs) rarely occur in young adults; in this age group, succinate dehydrogenase (SDH)-deficient subtypes predominate and may signal hereditary tumor syndromes. We present a 23-year-old male with a prior carotid paraganglioma who developed life-threatening iron deficiency anaemia (haemoglobin 4.0 g/dl) as the presenting manifestation of a high-grade gastric GIST. Subtotal gastrectomy with Billroth II reconstruction achieved R0 resection. Molecular testing was negative for KIT and PDGFRA mutations. Given the patient's age, mixed epithelioid/spindle histology, wild-type molecular profile, and paraganglioma history, Carney-Stratakis syndrome was suspected. SDHB immunohistochemistry confirmed an SDH-deficient phenotype, and germline testing identified a pathogenic heterozygous SDHx variant, establishing the diagnosis of Carney-Stratakis syndrome. At follow-up, the patient was clinically stable and enrolled in a multidisciplinary surveillance program. This case highlights the importance of recognizing atypical hematologic presentations of GIST and the need for comprehensive molecular and genetic evaluation in young patients.