Anonychia: Absence of nail. Describes a nail that has failed to develop.

Beau lines: Horizontal depression across a nail plate caused by transient arrest of nail growth. Causes could include any stressful event such as MI, PE, or high fever.

Blue nails: Causes include anti-malarial drugs, minocycline (a tetracycline), hemochromatosis (an iron metabolism disorder), Wilson dz, ochronosis (a metabolic disorder), and exposure to silver nitrate.

Brown nail: Occurs in Addison dz, hemochromatosis, gold therapy, arsenic intoxication, malignant melanoma, and Nelson syndrome

Dystrophic nail: A nail disorder due to faulty nutrition

Gray nail or gray lunula: Occurs in argyria (prolonged ingestion, injection, or mucosal absorption of silver nitrate)

Green nail: Pseudomonas infection

Hapalonychia: A rubbery and pliable nail plate usually caused by hyperhidrosis or endocrine disorders

Herpetic whitlow: Usually severely painful herpetic (viral) infection of the distal phalanx. Erythematous streaking of the extremity and enlarged lymph nodes may be noted.

Hippocratic nails (clubbing): Positive clubbing is noted when the Lovibond angle is greater than 180°. Lovibond angle is the angle between the nail plate and the proximal nail fold. Occurs in cardiac disease (cyanotic heart disease, bacterial endocarditis), pulmonary disease (primary and metastatic cancer, bronchiectasis, lung abscess, mesothelioma), or GI disease (enteritis, ulcerative colitis, and hepatic cirrhosis).

Intraungual hematoma: Hematoma within the body of the nail, due to trauma to the proximal nail fold. May take several weeks to develop because the nail must grow out.

Koilonychia (spoon nail): Seen in long-standing iron-deficiency anemia or Plummer-Vinson syndrome (a combination of koilonychia, dysphagia, and glossitis primarily seen in middle-aged women). Also known as Plummer’s nails.

Leukonychia: Nails exhibiting white spots (punctata) and/or striata

Lindsay nail (half and half nails): The distal half is pink or brown and is sharply demarcated from the proximal half, which is dull and white and obliterates the lunula. Seen in liver disease and azotemia (uremia).

Macronychia: Abnormally large nail

Mees lines: Single transverse white band associated with arsenic poisoning. A variation of Beau lines can also be seen following stressful events.

Melanonychia: Pigmented longitudinal bands in the nails. Normal variant usually seen in darker-skinned individuals.

Micronychia: Abnormally small nail

Muehrcke nails: Paired narrow horizontal white bands, separated by normal color, that remain immobile as the nail grows. Seen in hypoalbuminemia associated with nephrotic syndrome.

Onychatrophia: Atrophy of the nail

Onychauxic: Hypertrophy of the nail (thick nail)

Onychia: Inflammation of the matrix of the nail

Onychoclasis: Breaking of a nail

Onychocryptosis: Ingrown nail

Onychogenic: Producing nail substance

Onychogryphosis: A type of onychauxis (rams horn nail)

Onychoheterotopia: Abnormally placed nail on the digit as a result of displaced matrix material

Onycholysis: Separation of the nail plate from the nail bed. Begins distally and progresses proximally. Associated with many systemic diseases.

Onychomadesis: Separation of the nail from the nail bed, beginning proximally and progressing distally. Typically results in shedding of the nail. Seen in pemphigus vulgaris and hand, foot, and mouth disease.

Onychomalacia: Softening of the nail

Onychomycosis: Fungal nail

Onychophagia: Nail biting

Onychophosis: A callus in the nail groove

Onychopuntata: Pitting of the nails. Seen in psoriasis, alopecia areata, lichen planus

Onychorrhexis: Abnormal brittle nails with less than 16% water in nail. Normal nail hydration is between 16% and 30%

Onychoschizia: Splitting or lamination of the nail plate into layers that flake off

Onychotillomania: Neurotic picking or tearing at the nail

Paronychia: Inflammation involving the folds of tissue around the nail

Pterygium: The overgrowth of cuticle. May be normal variant or caused by lichen planus, dermatomyositis, or scleroderma.

Racquet nail: A short fat nail

Red lunula: Right-sided CHF

Splinter hemorrhages: Seen in subacute bacterial endocarditis and trichinosis, which is a disease from eating inadequately cooked meet infected with Trichinella spiralis. Patients will also have diarrhea, nausea/vomiting, and fever.

Subungual hematoma: Associated with acute trauma (dropping something on the toe). Hematoma develops instantly beneath the nail plate. Often, there is severe pain from the pressure of the blood beneath the nail plate, which can lead to increased necrosis of tissue. Drilling a hole in the nail or avulsing the nail may be necessary to relieve pressure.