Since Hippocrates first described “digital clubbing” in patients with empyema, Hippocratic fingers have been associated with several underlying pulmonary, cardiovascular, neoplastic, infectious, hepatobiliary, mediastinal, endocrine, and gastrointestinal diseases.
With no apparent underlying condition, the appearance of this disease can also occur as an idiopathic form of dominant Mendelian trait.
Clubbing, or Hippocratic fingers, is a clinically descriptive term referring to the uniform bulbous inflammation of the soft tissue of the terminal of the phalange of a digit with the consequent loss of the average angle between the nail and the nail bed.
The change of the phalanges of the fingers in the form of a thigh or fingernails in the form of a clock crystal (Hippocratic fingers) presents a well-known clinical phenomenon that suggests the presence of various diseases.
Especially those diseases associated with hypoxia, manifested by respiratory and cardiac insufficiency, malignant tumors, and subacute infective endocarditis.
At the same time, this clinical phenomenon may accompany other diseases (Crohn’s disease, HIV infection) must also be taken into account.
Hippocratic fingers often appear first, then more specific symptoms.
In this sense, the correct interpretation of this clinical sign, complemented by laboratory tests, allows an early and valid diagnosis.
Digital Clubbing is classified into primary (i.e., idiopathic, hereditary) and secondary forms. Digital Clubbing can be symmetrical bilaterally, or it can be unilateral or involves only one finger.
Anatomical considerations, such as the classical measurement of the Lovibond angle or the more recently derived index of the curvature of the nails by Goyal, can usually be identified in a simple physical examination and can be used to identify digital Clubbing and to control these dynamics objectively.
Several imaging modalities have been used to evaluate the fingers and help identify possible clues for their development.
Clubbing is a characteristic of Pachydermoperiostosis, a rare genodermatosis characterized by pachydermia, digital Clubbing, and hyperostosis, with a population of affected males.
Although it is usually an autosomal dominant model with incomplete penetrance and variable expression, both autosomal and recessive inheritance have been suggested in some families with Pachydermoperiostosis relatives.
Primary hypertrophic osteoarthropathy is a rare hereditary disorder with digital pairing, forming new subperiosteal bone and arthropathy.
It has been linked to mutations in the HPGD gene of 15-hydroxy-prostaglandin dehydrogenase (15-PGDH), which causes this.
A mutation was identified in a large Pakistani family with congenital Clubbing isolated on the nails.
In another study of homozygous mutations, an intragenic deletion resulting in a modification was associated with a severe phenotype. A heterozygous carrier of a mutation had isolated digital Clubbing.
The specific physiopathological mechanism of digital Clubbing remains unknown. Many theories have been proposed, but none has received widespread acceptance as a complete explanation of the phenomenon of digital Clubbing.
As Samuel West said in 1897, “Clubbing is one of those phenomena we are all so familiar with that we seem to know more about it than we really can.”
Alterations in the size and configuration of the fingers result from changes in the nail bed, beginning with the increase in interstitial edema at the beginning of the process.
As the musculature advances, the volume of the terminal portion of the finger may increase due to an increase in vascular connective tissue and to the change in vascular connective tissue quality. However, some cases have been associated with bone spurs in the terminal phalanx.
Although Clubbing is a common physical finding in many underlying pathological processes, surprisingly, the mechanism of how Clubbing occurs is unclear.
Different pathological processes can follow different paths towards a common goal. Many studies have shown an increase in blood flow in the portion of the fingers that have this syndrome.
High-resolution magnetic resonance images using a contrast agent in 4 patients with Clubbing and four healthy volunteers documented the hypervascularization of the nail bed as binding in affected patients.
Most researchers agree that this is due to an increase in digital distal vasodilation, whose cause is unknown.
The exact mechanism of increased blood flow changes in the vascular connective tissue under the nail bed is also unknown.
Idiopathic or primary Clubbing is rare, while the occurrence of secondary Clubbing depends on the underlying disease.
It has been reported that 89% of patients diagnosed with Pachydermoperiostosis have primary digital dysfunction. This syndrome occurs more often in young males.
Of the patients with idiopathic pulmonary fibrosis, 65% have clinical digital Clubbing. In these patients, a higher incidence has been observed in patients with higher levels of smooth muscle proliferation in the lungs.
In 29% of patients with lung cancer, it has been reported that Clubbing is more common in patients with non-small cell lung carcinoma (35%) than in patients with small-cell lung carcinoma (4%).
In 38% of patients with Crohn’s disease, digital discord was reported in 15% of patients with ulcerative colitis and 8% of patients with proctitis. Clubbing was observed in up to one-third of Ugandan patients with pulmonary tuberculosis. It was not associated with stages of HIV infection or hypoalbuminemia.
The racial preference for secondary Clubbing depends on the racial prevalence of the underlying disease.
The sexual predilection of secondary Clubbing of the fingers depends on the prevalence of the underlying disease.
Forecast: Hippocratic fingers
Since this condition is a clinical finding, it is not an independent cause of mortality; however, the mortality associated with the underlying pathology in patients with secondary Clubbing varies widely. Morbidity is minimal.
Treating the underlying pathological condition can decrease Clubbing or potentially reverse it if it is done early enough.