Pachydermoperiostosis (primary hypertrophic osteoarthropathy) is an orphan disease, the main clinical manifestations of which include pin-shaped deformity of the fingers according to the type of «drumsticks», periostosis (non-inflammatory changes of the periosteum) of tubular bones, pachydermia of the face (hypertrophy and hyperplasia of all skin layers). Two genes associated with the development of pachydermoperiostosis are known — HPGD and SLCO2A1. Mutations in these genes lead to impaired prostaglandin E2 metabolism. This article describes a clinical case of a patient with pachydermoperiostosis, in which two mutations in the HPGD gene were detected during a molecular genetic study: in 1 exon (chr4-174522451-T-A, NM_000860.6:c.1A>T) and in 2 exon (chr4-174521985-AG-, NM_000860.6:c.175_176del) in compound-heterozygous state, while the c.1A>T mutation was previously described once, and the revealed biallelic combination of mutations in the HPGD gene was not previously found in the literature. This clinical case of pachydermoperiostosis is the second described in the Russian population, and the first with confirmed mutations in the HPGD gene. The article expands the knowledge about the correlation of genotype and phenotype in pachydermoperiostosis, which contributes to a faster and more correct interpretation of genetic information during genetic counseling.