Changes in the finger nails associated with chronic pulmonary tuberculosis have been observed and recorded since the time of Hippocrates. These include: (1) proximodistal incurvation, (2) clubbing, (3) pitting or depressions in the nail plate, (4) longitudinal or transverse ridging, (5) cyanosis of the nails and (6) disappearance of the lunula.
Hahn1 published a statistical study on this subject in 1929. He found no hippocratic incurvation in normal controls, while it was present in 76 per cent of the patients with active tuberculosis, 50 per cent of the patients with inactive pulmonary tuberculosis and 30 per cent of the ex-patients working at his institution. Pittings and depressions in the finger nails were noted in all of his patients suffering from active pulmonary tuberculosis as compared with 6 per cent of patients in whom the disease had been inactive for a relatively short time; these changes were absent when