Pachydermoperiostosis (Gk pachys thick) is characterized by hypertrophic changes involving primarily the skin (pachydermia) and bones of the extremities (periostosis).
Primary pachydermoperiostosis (also called primary hypertrophic osteoarthropathy or Touraine–Solente–Golé syndrome) is a rare inherited disorder and occurs predominantly in males. It is sometimes autosomal dominant (with variable expressivity). At other times, it is autosomal recessive. Primary pachydermoperiostosis usually begins soon after puberty and progresses up to 10 years. Exceptionally, it may continue to progress. The skin of the face, forehead and scalp becomes grossly thickened and thrown into folds (coarse facial features, one of the leonine facies). The folding of the scalp produces one of the forms of cutis verticis gyrata. The skin of the hands and feet is also thickened, but often not folded. Thickening of the phalanges and of the bones of the limbs produces spade-like hands and feet with increased circumference of arms and legs/the fingers and toes are clubbed (related to altered proteoglycan synthesis). Reported associated features include e.g.: acro-osteolysis, sparse facial and pubic hair, gynaecomastia, seborrhoea of the face and scalp, palmoplantar hyperhidrosis, carpal and tarsal tunnel syndrome, and learning difficulties. Arthralgias can be debilitating. There are reports of resolution of the arthralgias when treated with tamoxifen.
Secondary pachydermoperiostosis (also called secondary hypertrophic osteoarthropathy) is usually provoked by serious pulmonary pathology such as bronchial carcinoma and lung abscess. Secondary pachydermoperiostosis occurs predominantly in men aged 30–70 years. The bone changes are the most obvious feature, develop more rapidly, and are usually painful. The skin changes may be absent and are usually relatively mild. When the primary disease is treated effectively, the bone and skin changes will regress. The primary and secondary forms of pachydermoperiostosis must be differentiated by the age of onset, the rate of progression and the presence of underlying pulmonary pathology.
Cranio-osteoarthropathy shares some features with primary pachydermoperiostosis [clubbing and hypertrophic osteoarthropathy], but patients do not have pachydermia. They typically present earlier in childhood and have delayed neurocranial ossification, with delayed closure of the fontanelles, and may also have congenital heart disease. Having said so, the overlap of clinical features suggests that primary pachydermoperiostosis and cranio-osteoarthropathy are allelic in some patients. In acromegaly, the facial skeleton, jaw and skull as a whole are enlarged, and visual defects may be detectable. In thyroid acropachy, enlargement is confined to hands and feet, and exophthalmos and pretibial myxoedema are often present, with other signs of hyperthyroidism.