Primary hypertrophic osteoarthropathy complicated with myelofibrosis and compound heterozygous SLCO2A1 mutations: a case report and review of literature.

Background: Primary hypertrophic osteoarthropathy (PHO) is a rare hereditary clinical syndrome characterized by digital clubbing, periostosis, and pachydermia. It is mainly caused by mutations in SLCO2A1 or HPGD, leading to impaired degradation and elevated levels of prostaglandin E2 (PGE2). In addition to the typical skeletal and skin manifestations, some patients may present with gastrointestinal or hematologic abnormalities, including anemia and myelofibrosis. This report describes a case of PHO with myelofibrosis and compound heterozygous SLCO2A1 mutations and review the literature. Case report: A 45-year-old man presented with a long history of severe fatigue and recurrent anemia accompanied by digital clubbing and skin thickening. Bone marrow biopsy revealed myelofibrosis, and imaging studies showed periostosis of the long bones. Given the anemia and gastrointestinal symptoms, differential diagnoses included Crohn's disease, intestinal tuberculosis, and other hematologic disorders associated with myelofibrosis, which were excluded by endoscopic and hematologic evaluations. Whole-exome sequencing revealed that the patient carried compound heterozygous variants in SLCO2A1 (c.940 + 1G>A and c.440G>A/p.Trp147*), confirming the diagnosis of PHO. Family investigation showed that his parents and offspring were all asymptomatic carriers with one heterozygous variant, which is consistent with autosomal recessive inheritance. Conclusion: Myelofibrosis is a rare but important complication of PHO and may be more frequent in patients with biallelic SLCO2A1 variants. Genetic testing and hematologic evaluation in PHO patients can help with early identification of related complications.