In nail diseases, symptoms manifest in the nail plate, the skin tissues surrounding the nails, the nail bed, and the lunula.

Different terminology is used for nail diseases based on their locations and symptoms, allowing for the classification of nail disorders.

Nail Plate Transformations: Changes in Size

Micronychia: If the nail matrix is narrower than it should be, a small nail plate is observed.

Brachyonychia: It defines the nail plate being shorter than it should be. It is commonly observed in toenails and is genetically inherited. It is rare in fingernails.

Anonychia: It refers to the absence of part or all of the nail. The nail plate may be very thin or entirely absent. It can be congenital, or damage to the nail matrix can lead to this clinical condition. When congenital, anonychia can be associated with growth retardation, abnormal facial appearance, and abnormal tooth development. In toenails, anonychia may be part of nail-patella syndrome.

Onychoatrophy: It can be congenital or develop due to skin diseases like lichen planus. The nail appears small with a decrease in thickness, volume, length, and width.

Hapalonychia: It is the condition where the nail plate is very thin.

Macronychia: It describes nails being larger than they should be. It is seen in conditions like Proteus syndrome, which involves gigantism.

Nail Plate Thickness Variations

Pachyonychia: It defines thickening of the nail plate. It can be observed in genetic disorders like “Pachyonychia congenita.” Additionally, it can manifest with aging when the longitudinal growth rate of the nail slows down. It can be seen in conditions like “Yellow Nail Syndrome.” In thick nails, the excessive thickening without longitudinal growth can lead to transverse ridges on the nails.

Onychogryphosis: It describes thick and elongated nails. Over time, nails can curve sideways, resembling a ram’s horn. It can occur with aging or is frequently observed with narrow shoes.

Diseases Arising from Nail Plate Shape

Clubbing, also known as “drumstick fingers,” is characterized by an increased longitudinal slope of the nails. In this condition, there may be soft tissue growth around the nail or the presence of cyanosis. It is also referred to as “Hippocratic nails.” Normally, the Lovibond angle between the nail and the nail fold is around 160°. In clubbing, this angle is increased to 180° or more. It can be associated with cardiovascular diseases, digestive system disorders, or have a familial predisposition.

Pincer Nail, or “trumpet nail,” describes an increased transverse curvature of the nail, resulting in a claw-like appearance. This condition can be painful and is often caused by trauma, tight footwear, or fungal infections.

Koilonychia, or “spoon-shaped nails,” is related to the nail plate having a concave, spoon-like appearance. It can be congenital or familial and may occur in conditions such as hypothyroidism or iron-deficiency anemia.

Changes in Nail Plate Color and Associated Diseases

Normally, the nail plate is colorless and transparent, allowing the pink color of the underlying nail bed to be visible. The lunula retains its inherent color structure, and the nail tip appears white due to onycholysis.

Nail color changes, or dyschromia, can affect the nail plate, nail bed, matrix, the skin fold around the nail, and the lunula.

• Leukonychia is the most commonly observed nail color change, often described as white nails. It can manifest across the entire nail, in part, or as pinpoint spots.
• Mees’ lines are horizontal white bands on the nails.
• Muehrcke’s lines…

Changes on the Surface of the Nail Plate and Associated Symptoms

The normal surface of the nail plate is flat and smooth. On the surface of the nail plate, pitting, swelling, ridges, and peeling can develop.

Pitting: Pits and depressions develop on the nail surface following issues with the nail matrix. The sizes of the pits vary. Pitting can occur due to conditions such as psoriasis, alopecia areata, and eczema.

Trachyonychia: It describes irregularities on the surface of the nail plate. When it affects all 20 nails, it is referred to as “twenty-nail dystrophy.” It can be observed in conditions like alopecia, lichen planus, psoriasis, and eczema.

Ridges and Grooves on the Surface of the Nail Plate

These can occur both transversely and longitudinally on the nail plate, originating from pathologies in the nail matrix and along the edges of the nails.

Beau’s lines: Transverse grooves appear on the nails due to a sudden halt in nail formation in the nail matrix. They are parallel to the lunula boundary when multiple nails are affected. The problem in the nail matrix can be understood based on the distance to the nail tip.

Habit tic related transverse ridges: Parallel longitudinal depressions occur on the nails due to repeated self-inflicted trauma by the patient.

Longitudinal depressions on the nails: Primarily related to a lesion occupying the nail bed and matrix, such as fibroma, wart, or myxoid cyst. It disappears when the primary focus is removed.

Onychorrhexis: Longitudinal, shallow grooves and ridges develop on the nail plate, most commonly observed in nail involvement in lichen planus.

Median nail dystrophy: Longitudinal grooving in the middle of the nail plate with a surrounding corrugation resembling a fir tree. The grooving and ridges in the nail plate lead to weakness and separations at the nail tip.

The Nail Symptoms Observed in Problems of the Nail Bed and Surrounding Support Tissues

Pterygium deformity: It develops due to focal damage in the nail matrix, leading to the absence of nail growth in that area. It is observed in conditions like lichen planus.

Onycholysis: It describes the separation of the nail plate from the nail bed. It can occur due to systemic diseases, external factors, skin disorders, and infections.

Onychomadesis: It occurs when the nail separates from the nail bed under the lunula, and a new nail grows underneath. It can be caused by systemic diseases, blistering disorders, drug reactions, and is sometimes idiopathic. In some cases, it may be associated with paronychia when it affects the proximal part.

Subungual hyperkeratosis: Thickening of the nail bed. This condition can occur in diseases such as psoriasis and eczema, onychomycosis, and genetic conditions (pachyonychia congenita).

Onychoschizia: It is the term used for peeling of the nail tips. It is observed in one-third of women and is more common in individuals with frequent hand exposure to water. The use of nail polishes and polish removers can also contribute to this condition. The first step in treatment involves discontinuing hand exposure to water and removing nail polishes. Improvement is typically seen within 21 days under these conditions, and moisturizers can be applied liberally during this period.

Changes Around the Nail

Infections, tumors, and skin conditions such as psoriasis can affect the skin around the nails.

Paronychia, also known as whitlow or felon, defines an infection of the skin around the nails. It is often caused by the inadequacy of the cuticle structure. Chronic paronychia can result from excessive exposure to water and detergents, causing cuticle damage. Red, swollen, and discharge-prone inflammation develops around the nail. Typically, staphylococcal organisms are the cause, and systemic antibiotics should be used. Pseudomonas can also be a causative agent.

Nail Symptoms and Diseases in the Lunula

The Color of the Lunula

• Red Lunula: The lunula can appear red in many systemic diseases and skin conditions. Sometimes, it can develop without an apparent cause. Red lunula can be associated with cardiovascular diseases, carbon monoxide poisoning, systemic lupus erythematosus (SLE), and alopecia areata.
• Small Red Spots on the Lunula: Psoriasis, alopecia areata, eczema, and IgA diseases can be associated with small red spots on the lunula.

Changing the Shape of the Lunula