Nail changes in systemic disease
Clubbing is characterized by increased nail plate curvature longitudinally and transversely with soft tissue hypertrophy of the digital pulp.
It may be seen in systemic diseases, such as cyanotic congenital heart diseases, infective endocarditis, primary and metastatic lung cancer, bronchiectasis, lung abscess, cystic fibrosis, inflammatory bowel disease, and hepatic cirrhosis.
Cyanosis may manifest as blue or purple discoloration of the nail bed and digits as a result of lower oxygen saturation causing accumulation of deoxyhemoglobin in the small blood vessels of the extremities. Central cyanosis is caused by congenital heart diseases and may manifest on mucosa and extremities, whereas peripheral cyanosis is usually diagnosed by examination of the nail and digits and is caused by vasoconstriction and diminished peripheral blood flow as occurs in cold exposure, shock, congestive cardiac failure, and peripheral vascular disease.
Nail pitting or trachyonychia -Pits result from a defective keratinization of the proximal matrix with persistence of parakeratotic cells in the nail plate surface.
It may occasionally be useful in diseases such as psoriasis, psoriatic arthritis , SLE, dermatomyositis, syphilis, sarcoidosis etc.
Leukonychia refers to the white discoloration of nail.
Muehrcke's lines
These are apparent leukonychia characterized by double white transverse line , resulting from a localized edematous state in the nail bed exerting pressure on the vascular bed. They are specific for hypoalbuminic state (occur in patients albumin is less than 2g/dL) and disappear when the protein level normalizes. Muehrcke's lines are seen in nephrotic syndrome, glomerulonephritis, liver disease, chemotherapeutic drugs, and malnutrition.
Half and half nail or Lindsay nail: Apparent leukonychia with a normal proximal half and abnormal brownish discolored distal half .
It is seen in patients of chronic kidney disease with uremic renal failure.
Splinter hemorrhages Splinter hemorrhages in nails are formed by the extravasation of blood from the longitudinally oriented vessels of the nail bed. They may be seen in the setting of infective endocarditis.
Koilonychia It is the presence of reverse curvature in the transverse and longitudinal axis, giving a concave dorsal aspect to the nail. These changes result in spooning of the nails capable of retaining a drop of water.
Koilonychia can be idiopathic or associated with a variety of conditions such as iron deficiency anemia (Plummer Vinson syndrome), malnutrition, hemochromatosis, coronary disease, thyroid disorders, Upper gastrointestinal malignancy etc.