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Pachydermoperiostosis (PDP) is a form of primary hypertrophic osteoarthropathy (see this term), a rare hereditary disorder, and is characterized by digital clubbing, pachydermia and subperiosteal new bone formation associated with pain, polyarthritis, cutis verticis gyrata, seborrhea and hyperhidrosis. Three forms have been described: a complete form with pachydermia and periostitis, an incomplete form with evidence of bone abnormalities but lacking pachydermia, and a forme frusta with prominent pachydermia and minimal-to-absent skeletal changes (see these terms). The prevalence is unknown. PDP occurs predominantly in men (male to female ratio: 7:1) and the disease is more severe in men than in women. PDP typically begins during childhood or adolescence and may stabilize after 5-20 years of progression, or progress constantly. However, in the neonatal period, late closure of the fontanels and a patent arterial duct (see this term) may be observed. PDP presents with digital clubbing and dermatological (pachydermia, thickening and furrowing of the facial features, cutis verticis gyrata, seborrhea, edema, hyperhidrosis) and rheumatological symptoms (joint effusion, arthritis, acro-osteolysis, periosteal ossification). Patients may develop severe kyphosis, restricted motion and neurological manifestations. PDP may also be associated with congenital heart disease, particularly patent arterial duct. PDP is inherited as an autosomal recessive trait; however, heterozygous carriers can have a mild phenotype. Mutations in the HPGD gene (4q33-q34) have been identified. The gene encodes 15-hydroxyprostaglandin dehydrogenase (15-PGDH), the main enzyme of prostaglandin degradation. Patients with homozygous mutations have chronically elevated prostaglandin E2 levels. Diagnosis is based on clinical signs, X-ray exam, magnetic resonance imaging and/or radionucleotide bone imaging showing typical bone abnormalities, such as diaphyseal periostosis and acro-osteolysis. Differential diagnoses include cranio-osteoarthropathy (see this term), secondary hypertrophic osteoarthropathy, chronic recurrent multifocal osteomyelitis, SAPHO and Camuratti-Engelman syndromes (see these terms), thyroid acropachy and syphilitic periostosis. Genetic counseling should be offered to patients and their families. Rheumatologic symptoms can be improved by nonsteroidal anti-inflammatory drugs or corticosteroids or colchicine. Clinical improvement of the dermatological symptoms is achieved by retinoids. Plastic surgery may be helpful for facial involvement. Surgical reduction of finger clubbing has been performed with success. PDP may progress constantly, leaving patients with chronic debilitating complications, such as clubbing and arthritis. |