Background: In three previous reports of primary hypertrophic osteoarthropathy, an associated extramedullary hematopoiesis was related to myelofibrosis.
Case report: A 44-year-old male patient with primary hypertrophic osteoarthropathy diagnosed when he was 34-year-old was referred to our hospital with an abdominal mass fortuitously detected.
Discussion: The present case is unique for the patient developed an extramedullary hematopoïesis without associated myelofibrosis. It suggests the possible intervention of growth factors common to the skin fibroblasts and the blood progenitor cells in the pathogenesis of primary osteoarthropathy.