Pseudoclubbing: is it different from clubbing?

OBJECTIVES: Contrary to digital clubbing, there is no clear definition for "pseudoclubbing" (PC). The aim of this study was to review the literature on this subject. Additionally, differences and similarities between clubbing and PC are shown.

METHODS: The PubMed database (1950-2006) was searched for the keyword "pseudoclubbing" and all published manuscripts and secondary references were examined. An additional search using the keywords "clubbing" and "hypertrophic osteoarthropathy"--and limited to those review types--was also undertaken and all relevant articles were examined.

RESULTS: Using the keyword "pseudoclubbing" in the PubMed database, we retrieved 10 articles that described 19 cases. Eleven of those cases were associated with renal failure/secondary hyperparathyroidism, 3 with subungual hemangioma, 2 with chromosomal deletion, 1 with sarcoidosis, 1 with primary hyperparathyroidism, and 1 with scleroderma. Of the 4 cases of PC seen in our institution, 3 associated with scleroderma and 1 associated with primary hyperparathyroidism are presented in this study. There is to be no convincing etiopathogenic mechanism for PC. The main features of PC were the asymmetric finger involvement observed in the large majority of the cases, but not in all, and acro-osteolysis, although this feature may also occur in "true" clubbing.

CONCLUSIONS: Although some characteristics have been noted in differentiating PC from clubbing, sometimes these features are not present.