SEMINAR PRESENTATION

APPLIED ANATOMY AND PHYSIOLOGY OF NAIL

MODERATORDR. R.S. MEENA

ANATOMY AND BIOLOGY OF THE NAIL UNIT

INTRODUCTION

nail apparatus - strong, relatively inflexible, keratinous

protective covering for fingertip allows precision and delicacy when picking

up small objects

SHORT EMBRYOLOGY

primitive epidermis – 9 - 20th wks. 20 wk

matrix cells show postnatal-type cell division differentiation and keratinization nail plate begins to form and move distally nail bed loses its granular layer at this stage.

36 wk: nail plate reaches the tip of the digit and is surrounded by prominent lateral nail folds and a well-formed cuticle.

NAIL BASIC STRUCTURE

1/4 nail is covered by the proximal nail fold Lunula (half-moon, lunule)

Under proximal part of nail most distal region of the matrix most prominent on thumb & great toe may be partly or completely concealed by the

proximal nail fold in other digits nail plate distal to lunula usually appears

pink, due to its translucency, which allows the redness of the vascular nail bed to be seen through it.

PROXIMAL NAIL FOLD two epithelial surfaces, dorsal and ventral, at the junction

of the two, the cuticle projects distally onto the nail surface.

LATERAL NAIL FOLDS continuity with the skin on the sides of the digit laterally,

and medially they are joined by the nail bed. THE MATRIX

subdivided into dorsal (ventral aspect of the proximal nail fold), intermediate (germinal matrix or matrix) and ventral (nail bed) sections.

two distinct areas may be visible, THE PROXIMAL LUNULA

AND THE LARGER PINK ZONE on seeing nail plate from above On close examination, two further distal zones can often

be identified , the distal yellowish-white margin and immediately proximal to this the onychodermal band

MICROSCOPIC ANATOMY

NAIL FOLDS The proximal nail folds are similar in structure

to the adjacent skin devoid of dermatoglyphic markings and

pilosebaceous glands. From the distal area of the proximal nail fold

the cuticle adheres to the upper surface of the nail plate

serves to protect the structures at the base of the nail, particularly the germinal matrix, from environmental insults

NAIL MATRIX (INTERMEDIATE MATRIX)

Nail matrix produces the nail plate The nail matrix contains melanocytes in the

lowest three cell layers and these donate pigment to the keratinocytes.

there is presence of 6.5 melanocytes per millimetre of matrix basement membrane

Langerhans cells are detectable in the matrix by CD1a staining, and the matrix appears to contain basement membrane components

NAIL BED

Nail bed consists of epidermis with underlying connective tissue closely apposed to the periosteum of the distal phalanx.

There is no subcutaneous fat in the nail bed The nail bed epidermis is usually two or three cells

thick The nail bed dermal collagen is mainly orientated

vertically, being directly attached to the phalangeal periosteum and the epidermal basal lamina.

Within the connective tissue network lie blood vessels, lymphatics, a fine network of elastic fibres and scattered fat cells; at the distal margin, eccrine sweat glands have been seen

NAIL PLATE

The nail plate comprises three horizontal layers: a thin dorsal lamina, the thicker intermediate lamina and a ventral layer from the nail bed

The nail plate contains significant amounts of phospholipid, mainly in the dorsal and intermediate layers, which contributes to its flexibility.

The nail plate is rich in calcium, found as the phosphate in hydroxyapatite crystals

Calcium does not significantly contribute to the hardness of the nail

NAIL KERATIN

Nail keratin analysis shows essentially the same fractions as in hair

amino acid analysis shows higher cysteine, glutamic acid and serine, and less tyrosine in nail compared with hair

normal nail demonstrates that the suprabasal keratin pair K1/K10 is found on both aspects of the proximal nail fold and to a lesser degree in the matrix. However, it is absent from the nail bed.

The nail bed contains keratin synthesized in normal basal layer epithelium, K5/K14, which is also found in nail matrix.

keratin pair K6/K16 are present in the nail bed but not in the germinal matrix

BLOOD SUPPLY OF NAIL

rich arterial blood supply to the nail bed and matrix derived from paired digital arteries, a large palmar and small dorsal digital artery on either side.

There are two main arterial arches (proximal and distal) supplying the nail bed and matrix, formed from anastomoses of the branches of the digital arteries.

Within the matrix, vessels are longitudinal with a helicoidal twisting..

There are many arteriovenous anastomoses beneath the nail— glomus bodies—which are concerned with heat regulation

Glomus bodies are important in maintaining acral circulation under cold conditions: arterioles constrict with cold but glomus bodies dilate.

Arterial supply of the distal finger.

NAIL GROWTH AND MORPHOLOGY

Cell kinetics Measured by immunohistochemistry,

autoradiography and direct measurement of matrix product (i.e. nail plate) by ultrasound ,micrometer or histology.

The rate of nail growth is about 3 mm/month for finger nails and about 1 mm/month for toe nails

NAIL MORPHOLOGY

The nail grows flat, rather than as a heaped-up keratinous mass factors probably responsible to produce a

relatively flat nail plate are orientation of the matrix rete pegs and papillae the direction of cell differentiation and

moulding of the direction of nail growth between the proximal nail fold and distal phalanx.

Containment laterally within the lateral nail folds assists this orientation

the adherent nature of the nail bed

PHYSIOLOGICAL AND ENVIRONMENTAL FACTORS AFFECTING THE RATE OF NAIL GROWTH.

FASTER SLOWER

DAYTIME NIGHT

PREGNANCY FIRST DAY OF LIFE

YOUTH,INCREASING AGE OLD AGE

FINGERS TOES AND THUMBS

MALE GENDER FEMALE

SUMMER WINTER

RIGHT HAND NAILS LEFT HAND NAILS

TRAUMA,NAIL BITING

PATHOLOGICAL FACTORS AFFECTING THE RATE OF NAIL GROWTH

FASTER SLOWER

PSORIASIS FINGER IMMOBILIZATION

PITYRIASIS RUBRA PILARIS

FEVER

HYPERTHYRODISM HYPOTHYRODISM

LEVODOPA YELLOW NAIL SYNDROME

ARTERIOVENOUS SHUNTS

BEAU’S LINES

BULLOUS ICTHYSIFORM ERYTHRODERMA

RELAPSING POLYCHONDRITIS

IDIOPATHIC ONYCHOLYSIS OF WOMEN

POOR NUTRITION

NAILS IN CHILDHOOD

In early childhood, the nail plate is relatively thin and may show temporary koilonychia

nails are also prone to terminal onychoschizia (lamellar splitting),most prominent on the sucked thumb.

Beau’s lines can be seen in up to 92% of normal infants between 8 and 9 weeks of age

A herringbone pattern is common in children and gradually diminishes with time, reflecting a gradual matrix maturation

NAILS IN OLD AGE

The whole subungual area in old age may show thickening of blood vessel walls with vascular elastic tissue fragmentation.

The nail plate becomes pallor, dull and opaque with advancing years

white nails similar to those seen in cirrhosis, uraemia and hypoalbuminaemia may be seen.

NAIL SIGNS AND SYSTEMIC DISEASE ABNORMALITIES OF SHAPE

CLUBBING -- In clubbing there is increased transverse and longitudinal nail

curvature with hypertrophy of the soft-tissue components of the digit pulp.

Hyperplasia of the fibrovascular tissue at the base of the nail also occurs.

Pathological associations of clubbing include ---inflammatory bowel disease, carcinoma of the bronchus and cirrhosis.

In forms associated with bronchiectasis or neoplasm, prominent inflammatory joint signs may also be seen, resulting in hypertrophic pulmonary osteoarthropathy

CLINICAL PICTURE OF CLUBBING

Lovibond’s angle is found at the junction between the nailplate and the proximal nail fold, and is normally less than 160°.This is altered to over 180° in clubbing

Curth’s angle atthe distal interphalangeal joint is normally about 180°. This isdiminished to less than 160° in clubbing

Schamroth’s window is seen when the dorsal aspects of two fingers from opposite hands are opposed, revealing a window of light, bordered laterally by the Lovibond angles. As this angle is obliterated in clubbing, the window closes.

In some cases of bronchiectasis, a variant of clubbing, shell nail syndrome is seen.

Distugunished from clubbing by the presence of atrophy of underlying bone and nail bed

KOILONYCHIA

Greek: koilos, hollow; onyx, nail In koilonchyia there is reverse curvature in

the transverse and longitudinal axes giving a concave dorsal aspect to the nail

most prominent in the thumb or great toe. common in infancy in toe nail Its persistence may be associated with a

deficiency of cysteine-rich keratin

a familial pattern which may be autosomal Dominant may be seen in some families

Most common systemic association is with iron deficiency and haemochromatosis

PINCER NAIL

Also known as trumpet or involuted nail Pincer nail describes a dystrophy where

nail growth is pitched towards the midline, combined with increased transverse curvature.

There are 3 variants of pincer nail1) In the inherited version there is often a

gradient of involvement, radiating from the thumbs and big toes outwards, which progresses with time.

2) the most common is in association with psoriasis, where the thumbs and big toes are the most likely to be affected, although the pattern is not as organised and symmetrical as that seen in the inherited version

3) The third variant is the individual nail which develops a pincer deformity.

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MACRONYCHIA AND MICRONYCHIA

Macronychia and micronychia are conditions where a nail is considered too large or too small in comparison with other nails

The nail disorder is usually associated with an abnormal digit, arising from underlying bony abnormalities such as local gigantism causing macronychia or megadactyly .

Also the basis of racket thumb, the most common form of benign, dominantly inherited macronychia

RACKET NAIL

ANONYCHIA

Anonychia is absence of all or part of one or several nails. It may be congenital, acquired or transient.

A mutation in the R-spondin 4 gene, which plays a part in Wnt signalling within the cell is responsible for congenital absence of nail

Acquired forms are due to scarring of the nail matrix. This can arise as a result of burns, surgery or trauma, or be due to inflammatory dermatoses such as lichen planus where the entire nail matrix is scarred and lost

The transient variant is due to nail shedding. This can occur due to an intense physiological or local inflammatory process,

ABNORMALITIES OF NAIL ATTACHMENT Nail shedding Nails may be lost through

different mechanisms 1) Complete loss of the nail

plate due to proximal nail separation extending distally is called onychomadesis and is a progression of profound Beau’s lines

2) Local dermatoses, such as the bullous disorders and paronychia, cause nail loss e.g. toxic epidermal necrolysis, lichen planus etc. 3) Trauma is a common cause of recurrent loss

It is often associated with subungual haemorrhage

4) Temporary loss has also been described due to drugs such as retinoids,cloxacillin and cephaloridine5) Onychoptosis defluvium or alopecia unguium describes atraumatic,familial, non-inflammatory nail loss6) Nail shedding can be part of an inherited structural defect, most obviously in epidermolysis bullosa7) Nail degloving this refers to partial or total avulsion of the nail and surrounding tissue (perionychium).Typically,it appears as thimble-shaped nail shedding or total loss of the nail organ with soft tissue

DIFFERENT EXAMPLES OF SEPERATION OF NAIL ATTACHMENT

ONYCHOLYSIS Onycholysis is the distal or lateral separation of the

nail from the nail bed Psoriatic onycholysis can be considered the reference

point for other forms of onycholysis where it is typically distal, with variable lateral involvement.

Areas of separation appear white or yellow due to air beneath the nail and sequestered debris, shed squames and glycoprotein exudate.

Isolated islands of onycholysis present as ‘oily spots’ or ‘salmon patches’ in the nail bed.

Idiopathic onycholysis This is a painless separation of the nail

from its bed, which occurs without apparent cause. Overzealous manicure, frequent wetting and cosmetic ‘solvents’ may be the cause.

The condition usually starts at the tip of one or more nails and extends to involve the distal third of the nail bed.

Onycholysis: idiopathic type

Fingernail in psoriasis

Secondary onycholysis Onycholysis due to other causes is secondary

onycholysis. It may be localised or systemic Psoriasis, fungal infections, dermatitis and trauma

are among the most common. Onycholysis occurs in general medical conditions, including impaired peripheral circulation, hypothyroidism ,hyperthyroidism , hyperhidrosis, yellow nail syndrome and shell nail syndrome

Photo-onycholysis may occur during treatment with psoralens, demethylchlortetracycline and doxycycline

PTERYGIUM

The term ‘pterygium’ describes the winged appearance achieved when a central fibrotic band divides a nail proximally in two.

inflammatory destructive process precedes pterygium formation.

There is fusion between the nail fold and underlying nail bed and matrix.

The fibrotic band then obstructs normal nail growth. It most typically develops in trauma or lichen planus

and its variants, including idiopathic atrophy of the nail and graft-versus-host disease

It can also occur in leprosy and secondary purulent infection.

Ventral Pterygium Ventral pterygium or pterygium inversum

unguis occurs on the distal undersurface of the nail

Causes include trauma, systemic sclerosis,Raynaud’s phenomenon, lupus erythematosus, familial and infective .

Subungual hyperkeratosis entails hyperkeratosis of the nail bed and hyponychium Nail plate thickening is common. Dry, white or yellow

hyperkeratosis may crumble away from the overhanging nail Hyperkeratosis may extend onto the digit pulp.

Features of onychomycosis and wart virus infection (mainly toes) or psoriasis, pityriasis rubra pilaris and eczema (mainly fingers) are found

The nail bed is an epithelium of low proliferative turnover. Any disease process that affects it is likely to result in an excess of squamous debris. The overlying nail prevents simple loss. The initial outcome is compaction of debris into layers of subungual hyperkeratosis.

Focal subungual keratoses seen with Darier’s disease, and keratotic debris beneath the nail in Norwegian (crusted).

CHANGES IN NAIL SURFACE

Longitudinal grooves Longitudinal grooves may run all or part of the

length of the nail in the longitudinal axis The median canaliform dystrophy of Heller is

the most distinctive form in this The nail is split, usually in the midline, with a

fir-tree-like appearance of ridges angled backwards.

The thumbs are most commonly affected and the involvement may be symmetrical.

TRANSVERSE GROOVES AND BEAU’S LINES

Transverse grooves may be full or partial thickness through the nail.

When they are endogenous they have an arcuate margin matching the lunula.

If exogenous, such as those due to manicure the margin may match the proximal nail fold and the grooves may be multiple as in washboard nails.

BEAU’S LINES

When the transverse groove’s are due to endogenous cause, the groove is better known as beau’s lines

PITTING

Pitting presents as punctate erosions in the nail surface

The individual pits of psoriasis are said to be less regular

An isolated large pit may produce a localized full thickness defect in the nail plate termed elkonyxis, which is found in Reiter’s disease, psoriasis and following trauma

TRACHYONYCHIA

Trachyonychia presents as a rough surface affecting all of the nail plate and up to 20 nails

The original French term was ‘sand-blasted nails’, which evokes the main clinical feature of a grey, roughened surface

mainly associated with alopecia areata, psoriasis and lichen planus

ONYCHOSCHIZIA

Onychoschizia is also known as lamellar dystrophy and is characterized by transverse splitting into layers at or near the free edge

It is seldom associated with any systemic disorder, although it has been reported with polycythaemia, human immuno-deficiency virus (HIV) infection and glucagonoma

CHANGES IN COLOUR

Alteration in nail colour may occur because of changes affecting the dorsal nail surface, the substance of the nail plate, the undersurface of the nail or the nail bed.

Exogenous pigment Exogenous pigment on the upper surface is

easy to demonstrate by scraping the nail. If the proximal margin of the pigment is an arc matching the proximal nail fold, this is a further clue confirming an exogenous source.

NAIL PLATE CHANGES

The nail plate can be changed by the addition of pigment or the alteration of the normal cellular and intercellular organization such that there is loss of normal lucency.

Normal Pigment is typically added in the form of melanin produced by matrix melanocytes during nail formation. This produces a brown longitudinal streak the entire length of the nail.

The incorporation of heavy metals and some drugs into the nail via the matrix can also produce altered nail plate colour, such as the grey colour associated with silver.

The disruption of normal nail plate formation by disease, chemotherapy, poisons or trauma can result in waves of parakeratotic nail cells or small splits between cells within the nail.

In fungal infection discoloration may start distolaterally rather than via the matrix.

NAIL BED CHANGES

Normally there is generalized vascular changes in the nail bed, but localized changes, as seen with nail bed tumours.

Subungual hyperkeratosis or the incorporation of drugs (antimalarials, phenothiazines) may also change the apparent colour of the nail.

Splinter haemorrhages, representing ruptured nail bed vessels, deposit haemoglobin on the undersurface of the nail, which grows out.

Cyanosis makes the nail bed blue and carbon monoxide poisoning makes it bright red.

LEUKONYCHIA

White discoloration of the nail attributable to matrix dysfunction is known as leukonychia.

In an inherited form called total leukonychia, all nails are milky porcelain white.

In subtotal leukonychia, the proximal two-thirds are white, becoming pink

distally. This is attributed to a delay in keratin maturation

Transverse leukonychia (Mees’ line) reflects a systemic disorder , such as chemotherapy or poisoning

APPARENT LEUKONYCHIA

In apparent leukonychia, changes in the nail bed are responsible for

the white appearance. Nail bed pallor may be a non-specific sign

of anaemia, oedema or vascular impairment.

TERRY’S NAIL

This is white proximally and normal distally Seen in cirrhosis, congestive cardiac failure and adult-

onset diabetes mellitus. Nail bed biopsy reveals only mild changes of increased vascularity. Terry’s nail is similar to half-and-half nails where,

there is a proximal white zone and distal (20–60%) brownish sharp demarcation,

the histology of half and half nail suggests an increase of vessel wall thickness and melanin deposition.

seen in 9–50% of patients with chronic renal failure and after chemotherapy

MUEHRCKE’S PAIRED WHITE BANDS These bands are parallel to the lunula

in the nail bed, with pink between two white lines.

They are commonly associated with hypoalbuminaemia

the correction of hypoalbuminaemia by albumin infusion can reverse the sign.

COLOUR CHANGES DUE TO DRUGS

Yellowing of the nail is a rare occurrence in prolonged tetracycline therapy, which can also produce a pattern of dark distal photo-onycholysis associated with photosensitivity

BLUE MEPACRINE

BLUE-BLACK

CHLOROQUINE

DARK BLUE

DRUG ERUPTION

HYPERPIGMENTATION

DOXORUBICIN IN CHILDREN

YELLOW NAIL SYNDROME

•The nails in yellow nail syndrome are yellow due to thickening,•a tinge of green suggets secondary infection.•The lunula is obscured •increased transverse and longitudinal curvature •loss of cuticle•chronic paronychia with onycholysis and transverse ridging may occur• The condition usually presents in adults

YELLOW NAIL SYNDROME

An autosomal dominnant inheritance is suspected

lymphoedema at one or more sites may accomapany

respiratory or nasal sinus disease may present

Also occur in d-penicillamine therapy and nephrotic syndrome ,hypothyroidism & AIDS

Attempted treatments include oral and topical vitamin E, oral zinc

LONGITUDINAL ERYTHRONYCHIA

•It is a longitudinal red streak in the nail•Forms a strip where the nail bed is less compressed by the overlying nail so that blood pools• color is more easily seen because the nail is thinner in this line. •Splinter hemorrhages may lie longitudinally•Seen with lichen planus & darrier’s disease , acrokeratosis verruciformis

ONYCHOPAPILLOMA

Describe the isolated, benign warty distal nail bed lesions

term coined by baran Can be associated with longitudinal

erythronychia The papilloma is a secondary element, given

that it is found distally in the nail bed while the cause lies proximally within the matrix.

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Thank you