• Damage to the nail as a result of trauma or disease results in nail dystrophy
• This is defined as the presence of a misshapen or partially destroyed nail plate
• Soft yellow keratin often accumulates between the dystrophic nail plate, resulting in elevation of the plate

Types of Nail diseases:

Onychomycosis:

• Fungal infection is an extremely common cause of toenail dystrophy
• Great toe nail is extremely prone to infection
• Infection of fingernails may occur in nails previously traumatized or when nail involvement is part of tinea mannum
• Onycholysis: separation of nail plate from nail bed
• Subungual hyperkeratosis: buildup of soft yellow keratin in the space created by the onycholysis, usually asymptomatic
• Most due to Trichophyton rubrum, but in a few cases, Epidermyophyton floccosum and Trichophyton mentagrophytes may be recovered. Diagnosis can be made by culture
• Treatment is terbenafine or itraconazole orally

Psoriasis:

• Onycholysis, subungual hyperkeratosis, nail pitting, yellowish discoloration
• More serious nail dystrophies are often accompanied by inflammatory, arthritic changes in the distal interphalangeal joint
• Extremely difficult to treat

Beau's Grooves:

• 1 mm wide depression in the nail plate that extends horizontally from one lateral nail groove to the other
• All nails are simultaneously affected
• Most commonly develop following dramatic illness such as MI and periods of high fever or malnutrition

Clubbing:

• Lovibond’s angle greater than 180 degrees, most commonly seen with chronic pulmonary or cardiopulmonary disease but also occurs with some tumors, especially those of the lung parenchyma

Periungual Warts:

• Often distort the nail plate
• In most instances, the dystrophy is not permanent and the nail plate returns to normal following therapeutic or spontaneous resolution of the warts

White banding of nails:

• Horizontal white banding or opacification occurs in hypoalbuminemia accompanying chronic hepatic or renal disease

Brown banding of nails:

• Vertical - secondary to nevus or melanoma
• Horizontal - Addison's disease, cancer chemotherapy

Splinter hemorrhages:

• Thin dark red lines 1-3 mm in length, representing small hemorrhages at the junction of the nail plate and the nail bed. They move out as the nail grows.
• Seen with bacterial endocarditis, trichinosis, but frequently seen in normal individuals

Candidal Paronychia:

• Most common cause of paronychial inflammation and swelling of the fingers
• Seen in dishwashers, bartenders and waitresses
• Characterized by lack of pain, lack of warmth, absence of pus, chronicity

Bacterial Paronychia:

• Usually caused by Staphylococcus
• Redness, warmth, swelling and tenderness

Koilonychia:

• Spoon-shaped nails may be due to iron deficiency