Most common nail diseases

Pavel Konrád, Dermatology Clinic, Černošice

SUMMARY: The article describes the most common non-mycotic disorders of the nail plates and their immediate surroundings. This article also describes the etiopathogenesis, clinical picture and therapy of each lesion.

KEY WORDS: onychodystrophy, onycholysis, remineralization, chitosan salicylate, orthosilicic acid, methylsulfonylmethane, mastic gum.

The Anatomy and Physiology of the Nail

Nehet (Lat. unguis, Greek: onyx-onychos) is a callous derivative of the skin covering the tip of the fingers. It is made up of the nail matrix – germinal tissue, from which the nail plate grows, moving away along the nail bed. Proximally and laterally, the nail ridges, the eponychia and the hyponychia make up the border and protect the nail from outer influences. Most of the matrix is hidden under the proximal nail ridge and only 1/3 is visible 1/3 on the nail plate, as a crescent whitish colour, called the lunula. The matrix has 2 parts – the proximal and the distal, from which the dorsal and ventral parts of the nail plate grow. The nail is made up of approx. 150 – 200 layers of callous keratinocytes – corneocytes.^[1] Nails grow at a rate of approx. 0.9mm per week. The nail on the middle finger grows the fastest. In some skin diseases (psoriasis vulgaris), nails grow faster and in some they grow slower (lichen planus). The nail plate transmits approx. 3% UVB and 10% UVA rays. An interesting fact is the trans-corneal water loss through the healthy nail plate, which is 100 times greater than through the callous skin. Under normal circumstances, the nail plate is transparent and smooth. In old age, the nail plate is longitudinally grooved and oftentimes shingled-like (onychodystrophia schindelamoides Stühmer).^[2]

Definition

Onychodystrophy of the nail is a collective name for changes indicating damage to the nail plate. This occurs when the nail matrix or nail bed is affected by a wide range of evoking factors, including infections, inflammations, tumours, systemic and inborn diseases. Depending on the location, length and mechanism of damage, pathological conditions of the nail apparatus arise, presenting a diverse clinical picture.^[3]

Aetiology and Pathogenesis

The issue with nail pathologies is extensive. In clinical practice, we most often see fungal infections of the nail plates, which are not the topic of this article. Other nail diseases can be divided according to many characteristics, like the clinical picture, the localization of the damage or the evoking factors.

The following categorization is the clearest:

A change in the shape and relief of the nail plate
A change in the colour of the nail plate
Damage to the nail bed

A change in the shape and relief of the nail plate

Onychoschisis (Greek: schisis – splitting)

This is when the nail plate splits in at least two layers from the free edge of the nail (Fig. 1). It is oftentimes caused by direct trauma of the nail plate, ex.: playing a musical instrument or chemical nox – sodium lauryl sulphate in detergents, and nail polish removers.^[4]

Onychorrhexis (Greek: rhexis – crack)

Excessively brittle nails manifested by breaking off or splitting of the free edge of the nail. The disorder is related to age or repeat contact with dissolvers. It occurs in diseases, like lichen planus, hyperthyreosis, hypovitaminosis A and B or hypocalcaemia.

Onychotillomania (Greek: tillein – rip, Greek: mania – passion)

Repeat damage of the nail caused by scissors, a knife or nail biting.

Beau’s Lines

Transverse lines in the form of grooves parallel to the lunula are known as Beau’s Lines and retrospectively reflect a series of pathological processes (Fig. 2). They affect the entire thickness of the nail plate and occur several weeks after illnesses accompanies by fever (typhus, scarlet fever, the flu or serious strep throat). It is possible to determine the time of the nox that evoked it. 5-6 months in thumbs and up to 2 years in the big toe. Beau’s Lines are evoked by a temporary reduction in the matrix activity. In addition to the consequences of the disease, they are the cause of trauma from an improper manicure, tics, a zinc deficiency or chemotherapy. They are analogous to Pohl-Pincus lines in hair follicles.^[1]

Dystrophia mediana canaliformis (Heller)

This is an unusual condition characterized by a deep groove running through the centre of the nail, starting in the cuticle area and continuing on to the free edge of the nail. In the cases described the Heller numerous transverse defects diverge from this central defect, so the finding resembles a feather or an inverted fir tree (Fig. 3a, 3b). The problem is usually symmetrical and may disappear with time. However, recurrence is not rare. It is either inborn or post-traumatic.^[1,5]

Pterygium unguis (Greek: pteryx – wing)

In winged-nails, there is severe damage to the matrix, ex.: in circulatory disorders or scleroderma, the nail detaches and the skin around the nail overgrows the nail bed.^[1]

Onychosis punctata

The surface of the nail is covered with small dot-like depressions of various size, depth and shape (Fig. 4). The depth and range correspond with the degree of matrix damage. Deep depressions are seen in psoriasis and shallow depressions are seen in alopecia areata, eczema and occupational traumas.^[1]

Trachyonychia (Greek: trachys – rough)

The nail plate resembles sand paper. The causes are inborn, familial and acquired as a result of a series of chemicals or traumas (Fig. 5). All 20 of these nail plates may be damaged like that in alopecia areata, lichen planus and psoriasis. Rarer dermatosis, in which these changes are observed include ichthyosis vulgaris, knuckle pads, vitiligo and ectodermal dysplasia.^[1]

Onychogryphosis (Greek: grýpos – clawed, crooked)

It mainly affects the nail plate on the big toe. It causes thickening, roughness and opacity loss of the nail plate on the hyperplastic nail bed. In advanced stages, the nail plate curves along the fingers like an antler. This is often caused by show pressure, a lack of care in the elderly, in demented people or people with damage to the central nervous system and otherwise neglected individuals (ex.: the homeless). Another local cause is show pressure in patients with halluces valgi. It is less commonly associated with some dermatoses (ichthyosis, pemphigus, psoriasis, onychomycosis).^[1]

Dolichonychia (Greek: dolichos – long)

Such a nail plate is extremely long and narrow. The coefficient between the length and width of the nail plate is greater than 1.9 in dolichonychia. They are most commonly associated with the Ehler-Danlos and Marfan syndromes. It may also occur in eunuchoidism and hypopituitarism.^[1]

Clubbed fingers (Hippocrates, hour-glass shaped nails)

Morphological changes are a combination of accentuated transverse and longitudinal curvature of the nail with firmer soft structures strictly localized at the finger tips. The curvature angle between the proximal and distal phalanx is 160 to 140 degrees (Fig. 6). The pathological process responsible for the curvature is associated with increased blood flow as a result of vasodilation rather than the vascular hyperplasia of the whole nail bed. There are rare congenital forms, so called “hour-glass shaped nails”, symmetric and unilateral. Usually, this modification of the nail configuration is acquired. In 80% of the cases, the reason for the pathological processes is thoracal due to hypoxia: bronchial-pulmonary cysts, abscesses, bronchiectasis, tuberculosis, sarcoidosis, emphysema, mucoviscidosis and asthma in childhood. Other reasons include tumours: primary bronchial-pulmonary carcinoma, pleural tumours, mediastinal tumours and M. Hodgkin. Cardiovascular diseases, like inborn heart defects associated with cyanosis or vascular malformation are also responsible for this problem. In 5% of the cases, clubbed fingers are associated with diseases of the gastro-intestinal tract, which can include stomach, oesophagus or intestinal cancer, disease of the small and large intestine, Crohn’s disease and ulcerative colitis.^[1]

Koilonychia (Greek: koilos – hollow)

Koilonychia is the opposite of clubbed fingers. The nail plates are concave, spoon-shaped (Fig. 7). The fingernails are affected most often. Koilonychia on the toes are rare, but are physiological on the big toe until the first year of life. Idiopathic forms are hereditary and congenital. Sometimes, they also occur with other pathologies, like adenoma sebaceous Pringle, monilethrix, Meleda type palm hyperkeratosis, nail-patella syndrome and leukonychia. Acquired forms occur in cardiovascular and haematological diseases (sideropenia, polycytemia, hemochromatosis), infectious (mycoses, syphilis), endocrine (acromegalia, diabetes mellitus, hypo-thyroideus, thyrotoxicosis). They may be caused by traumas, avitaminoses (PP, B2, C). They are also present in some dermatoses (acanthosis nigricans, alopecia areata, connective tissue diseases, lichen planus, psoriasis).

They may occur after a kidney transplant or they occur in the carpal tunnel syndrome.

A change in the colour of the nail plate

Leukonychia (Greek: leukos – white)

Leukonychia are white changes of the nail plate (Fig. 8). Defective keratinization of the distal gives rise to parakeratotic cells that are visible on the nail plate as dull, whitish deposits or stripes. They usually disappear before reaching the distal edges. The main cause is microtrauma and it occurs more often in children.^[3]

Melanonychia (Greek: melanos – black)

Longitudinal melanonychia is a brown or black pigmentation strip on the nail conditional upon the presence of melanin (Fig. 9). Periungual spread of the pigment under the proximal or lateral nail bed is called the Hutchinson symptom. Its presence increases the suspicious of a melanoma. The Hutchinson symptom is also present in 1/3 of nail nevi and nail lentigines, in the Laugier-Hunziker syndrome (endobucal lentiginosis, melanonychia striata on one or more fingers, periungual pigmentation resembling í Hutchinson’s, pigmented macules on the mucous membrane of the oral cavity and the genitals), ethnic pigmentation or when taking certain systemic therapy. In these cases, it is called pseudo-Hutchinson’s signs. Most cases of melanonychia in adulthood are based on increased melanocyte activation without increasing the number of melanocytes. Physiologically, this happens in pregnant women, in people with dark skin, in pathological conditions, it occurs during traumas, in dermatosis, onychomycosis, systemic diseases (endocrine disorders, hyperbilirubinemia, alkaptonuria, hemosiderosis, porphyria, AIDS), in syndromes (Peutz-Jeghers syndrome, Laugier-Hunziker syndrome) and iatrogenic (X-rays, photo-therapy, systemic drugs – most commonly, bleomycin, cyclophosphamide, methotrexate, hydroxyurea, psoralene, steroids, fluconazole).^[3]

Erytronychia (Greek: erythros – red)

Pink to red colour changes of the nail plate. It is caused by too much blood around the nail bed due to various pathological conditions. When tumours are affected, it usually only affects one nail. Several nails are usually affected in Darier’s disease, lichen planus, systemic amyloidosis, epidermolysis bullosa and graft versus host.^[3]

Damage to the nail bed

Onycholysis (Greek: lyein – to release, to dissolve)

Partial separation of the nail plate from the nail bed starting from the free end of the nail and progressing proximally (Fig. 10). In onycholyses, a subungual space is formed, where keratin residue, detritus and air are deposited. Therefore, separated nail appears white but not structurally altered. This disorder most often occurs in psoriasis, eczema, lichen, a post-traumatic or drug reaction (tetracycline, taxans).^[4]

Onychomadesis (Greek: madésis – loss)

A total separation of the nail plate from the nail bed and nail matrix, followed by a separation of the whole nail (Fig. 11). A rare occurrence. When one nail separates, it is usually a post-traumatic change (subungual hematoma). When more nails separate, it is most often caused by a streptococci infection – scarlatina, Coxsackie viral infection or a reaction to drugs – Lyell’s syndrome. In addition, it occurs after skin diseases, like lichen planus and alopecia areata.^[2,4]

Diagnosis

The diagnosis is given by the clinical finding, the anamnesis and the course.

Therapy

Therapy is divided into local and general. For all of the above-mentioned nail diseases, both simultaneously is a desirable indicate.

Several substances are used in local therapy, which have a clinically proven effect on strengthening and re-mineralizing the nail plate. The basic substance for local nail therapy is silicon (Latin: silicium). It is best biologically available in the form of ortho-silicic acid. In this form, it is most easily acquired from millet seeds extracts (Panicum miliaceum). Silicon re-mineralizes the nail, renews the structure of the nail and improves its strength and elasticity.

The second basic substance is chitosan salicylate, which is ideally also acquired from purely natural sources. It helps transport substances to the nail plate, to create a protective barrier, which reduces the brittleness of the nails and accelerates their growth. In addition, it has antimicrobial effects.

Metylsulfonylmethane (dimethyl sulfone) is the third basic substance in local treatment of nail disorders. It stabilizes proteins, thereby improving the nail’s strength and elasticity, strengthening the bonds between the layers of the nail, thereby making the nail plate harder.

Another proven substance, which has been used as a nail and hair balm for centuries in the Mediterranean is oil from the resin of a Pistacia lentiscus tree, called mastic gum oil. It accelerates the synthesis of keratin, thereby increasing the nail’s thickness. Pistacia lentiscus tree oil contains numerous biologically active molecules, including essential oils, the main components of which are α-pine, b-myrcene, b-pine, linalool, limonene and caryophyllene. In vitro shows that it increases the synthesis of hard keratins (K31, K83, K85), it increases the amount of silicon and in vivo, it improves the nail’s strength and thickness.^[6]

The most suitable galenic form of dermatologic product is a lacquer. Its characteristic is that it sticks to the nail plate, guaranteeing that the active substances reliably penetrate into the nail plate.

Onysil^® lacquer is a combination of the above-stated basic substances.

The lacquer washes off with water. Therefore, it should be applied to a dry nail plate, preferably at night, before going to bed.

In general therapy, the drugs of choice include essential amino-acids, methionine and cysteine in sufficient doses, which means at least 1000mg of methionine and 200mg of cysteine every day. These substances are an important part of the protein, keratin, which is the basic building block of hair and nails. Vitamin B, including panthenol and biotin (ex.: Methionine Complex cps) are also recommended. Zinc supplements are also suitable. Zinc gluconate is an absorbable form of zinc, which promotes hair and nail growth (even healing ulcers and wounds).^[7]

Conclusion

Nail disease is common and sometimes, it unfortunately cannot be treated. The symptoms are visible at first glance and the patients often suffer psychologically. The aim of therapy is to accelerate the healing process of the nail plate. In the case of hereditary aetiology, to improve the cosmetic appearance of the nails.

MUDr. et MUDr. Pavel Konrád

Dermatology Clinic
Mokropeská 2027, 252 28 Černošice
pavel.konrad@volny.cz

Literature:

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BRAUN-FALCO, O., PLEWIG, G., WOLF, H. Dermatology and Venerology, Osveta, Ltd., Martin, 2001, p. 486–488
STUMPFOVÁ A. Nail Disease and Pathology, Dermatology for Practice 2017; 11(2): 64–70
HERCOGOVÁ, J. Clinical Dermato-Venerology, Prague: Mladá fronta 2019, p. 279-587.
ŠTORK, J. et al. Dermato-Venerology, Prague Galén, 2008, p. 285–288
PIRACCINI, B.M., Clinical and Instrumental Objective Evidence of the Efficacy of a New Water-Based Nail-Strengthening Solution Containing Pistacia lentiscus and Hyaluronic Acid Applied for Up to 6 Months to Improve the Appearance of Weak, Brittle Nails. Dermatol Ther (Heidelberg) 10. 2020 Nov, 119–131 s.
FADRHONCOVÁ, A. Pharmacotherapy of Skin Disease, Prague: Grada 1999, p. 363–364