Osteoporotic vertebral fractures are uncommon in young adults and usually indicate an underlying disease. Systemic mastocytosis is a myeloproliferative neoplasm, which can be associated with osteoporosis. A previously healthy 30-year-old man presented with an L4 burst fracture after lifting a heavy object. He was operated with laminectomy and posterior lumbar instrumentation. During surgery, abnormally soft bone was noted. Postoperatively, osteoporosis was confirmed with measurement of bone mineral density. Further investigation revealed elevated serum tryptase levels while bone marrow biopsy findings showed systemic mastocytosis. He was also tested positive for D816V KIT mutation. Treatment with biphosphonates and interferon was initiated. No extraskeletal involvement was noted up to the last checkup, 18 months after the first presentation. Abrupt vertebral fractures in apparently healthy young individuals should raise the suspicion of an underlying pathology. Prompt identification and treatment of systemic mastocytosis is crucial in order to avoid unexpected sequelae.