Description

A 63-year-old man presented with chronic multiple joint pain and swelling. The symptoms had started in adolescence, progressed for about 10–15 years, and then became constant. There was no associated morning stiffness. Symptoms suggesting any chest or abdominal disease were absent. Family history was unremarkable. Physical examination revealed clubbing and bulbous swelling of all fingers and toes, and enlargement of the distal third of both forearms and legs (figure 1). Motion at all joints was mildly restricted. There were no skin changes. Cardiovascular, respiratory, and abdominal examinations were normal. Radiographs showed extensive periosteal changes in the long bones of bilateral forearms and legs, and small bones of hands and feet (figure 2). Chest X-ray, ECG, echocardiogram, and abdominal ultrasonography were normal. All laboratory investigations were normal. A diagnosis of incomplete primary hypertrophic osteoarthropathy (PHOA), which is an extremely rare condition, was made. The patient was prescribed etoricoxib once daily and physical therapy was advised. At 1-year follow-up, the pain had subsided and motion at the joints had improved.

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Figure 1

Clubbing and bulbous swelling of all (A) fingers and (B) toes with the widening of the distal part of both legs.

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Figure 2

Radiographic assessment. (A) Bilateral hands with a solid, smooth periosteal reaction involving the proximal and middle phalanges, a bulbous increase of soft tissue in the distal phalangeal region and mild terminal acro-osteolysis; (A–C) Shaggy periosteal reaction involving the epiphysis, metaphysis and diaphysis of radius, ulna, femur, tibia and fibula.

Hypertrophic osteoarthropathy (HOA) is a syndrome of digital clubbing, periosteal new bone formation, and arthritis. It is of two types: (a) secondary HOA associated with a primary underlying disease, and (b) PHOA or idiopathic HOA. PHOA, constituting 3%–5% of all hypertrophic osteoarthropathies, is an autosomal dominant or recessive condition thought to be caused due to impaired metabolism of prostaglandin E2 (PGE2).1 2 It is also known as pachydermoperiostosis due to the coarse facial features resulting from thickening and furrowing of skin (pachydermia) and has three clinical variants: (a) complete form, with both pachydermia and periostosis, (b) incomplete form, with periostosis but lacking pachydermia (as seen in our patient) and (c) fruste form, with prominent skin changes but minimal periostosis.3 It is important to differentiate between the primary and secondary forms as the latter is associated with cardiopulmonary and abdominal diseases and malignancies. In the primary type, there is generally an insidious onset during adolescence and gradual progression until it becomes stationary, there is familial involvement in about 60% of the cases, and the periosteal changes involve the diametaphyseal and epiphyseal regions. In contrast, the secondary type has an acute onset and rapid progression along with a waxing-and-waning nature depending on the activity of the aetiologic lesion, is non-hereditary and the epiphyseal region is typically spared. Other similar conditions that can cause confusion include acromegaly, thyroid acropachy, rheumatoid arthritis, multifocal periostitis, osteitis deformans and osteopetrosis.4 Non-steroidal anti-inflammatory drugs relieve pain and swelling of joints by blocking PGE2 synthesis. The use of bisphosphonates and glucocorticoids has also been proposed.2 Although patients with PHOA have a good prognosis with a normal lifespan, they need to be under regular and long follow-up as complications like ptosis, deafness, kyphosis, osteonecrosis and carpal tunnel syndrome can arise as a result of increased soft tissue bulk and hyperostosis.5