HAIR SHAFT DISORDERS

FRACTURES: TRICHOCLASIS: Green stick fracture of the shaft due to weathering and cosmetic defect. TRICHOPTILOSIS: (SPLIT HAIR) : Longitudinal fracture of hair shaft towards the tip. Occurs due to mechanical

and chemical trauma TRICHOTHIODYSTROPHY: (LOW CYSTEINE CONTENT IN HAIR--- POOR TENSILE STRENGTH) The hair breaks with

a clean cut (trichoschisis). Polarizing microscope shows alternating dark and bright zones showing a ‘tiger tail pattern’. Scanning electron microscope reveals severe cuticular defects and secondary cortical degeneration. The classification of trichothiodystrophy is :

A. Isolated hair defectB. A+ nail dystrophyC. B+ mental retardationD. C+ growth retardationE. D+ decreased fertilityF. E+ IcthyosisG. F+ PhotosensitivityH. G+ neutropenia.

NODES:

TRICHORRHEXIS NODOSA: These appear as minute grey nodes along the shaft where the cuticle is lost and the frayed cortical fibres project out giving the appearance of two paint brushes thrust into one another. Hair kink or break at the nodes. Causes are:

A. Acquired---- Mechanical and Chemical trauma(Most common cause). It affects the distal part of the hair. It affects only the scalp hair.

B. Familial---- It is accompanied by nail and teeth defect. Here the process may involve the proximal shafts and involve other body hairs other than the scalp hair.

C. In association with Menke’s kinky hair syndrome, Nethertons syndrome and trichothiodystrophy.

PSUEDOMONELITHRIX: The hair shaft shows irregular flattened and expanded areas that have an indented appearance. This results from--- TRAUMA OF FORCEPS, COMPRESSION BY OVERLAPPING HAIR.

TRICHORHHEXIS INVAGINATA: ( bamboo hair) The hair shaft is invaginated into itself resulting in a ball and socket type of defect. This is due softness in the cortex in the keratogenous zone resulting from incomplete conversion of sulfhydryl (S-H) to disulfide(S-S) groups. The hairs become dry,brittle and short.

An autosomally recessive trait : NETHERTON’S SYNDROME is C/B : Trichorrhexis invaginata Atopic dermatitis Ichthyosis linearis circumflexa Recurrent infections and immunologic defects Growth retardation.

TRICHONODOSIS(knotted hair): In curly hair persons , combing may produce knots in the hair where the shaft may break.

INFECTIVE: NITS, TRICHOMYCOSIS AXILLARIS, PIEDRA. HAIR CASTS: These probably are the remains of IRS that have failed to disintegrate properly. The appear grey.

They are seen commonly in inflammatory disease of the scalp.

MULTIPLE HAIR:

PILI BIGEMINI: 2 hair bulbs with saperate shafts emerge from the same follicular opening. PILI MULTIGEMINI: 2-8 MATRICES AND PAPILLAE form hair with saperate IRS in the same follicular canal.

Commonest in the jawline. TRICHOSTASIS SPINULOSA: It resembles comedones nad present on the nose, forehead, cheeks, upper back,

shoulder and upper arms. On closer inspection the ‘Comedones’ show up as a tuft of tiny hairs projecting through a keratotic plug. Microscopic examination shows 25-50 telogen vellus hairs embedded within the plug.

NARROWINGS:

MONELITHRIX: (monile= necklace; thrix= hair) autosomal dominant. It is due to a mutation in the hair keratin type 1 controlling genes on chromosome 12q--------- defective

cortical keratinization. The affected hairs are beaded and brittle. The beaded appearance is due to alternate zones of spindle

like thickening and thinning placed about 1 mm apart. A break occurs commonly at the internodal junction where the cortex is defective and medulla is absent.

Hair loss is mild to severe due to hair fragility that results in 1-2cm long broken hair. Some of the broken hair stubs project from the keratotic follicular papules especially on the occiput and nape of the neck.

It may be associated with trichorrhexis nodosa, nail and teeth defects, retarded growth and juvenile cataracts.

Treatment includes: AVOIDANCE OF MECHANICAL AND CHEMICAL TRAUMA+ ORAL ETRITINATE. POHL-PINCUS MARK:

This corresponds to the beau’s lines in case of hair. These are localized areas of shaft thinning corresponding with area of severe systemic stress.

TAPERED HAIR: The shaft shows gradual tapering to a point (pencil pointing) due to inhibition of matrix activity as in anagen effluvium.

EXCLAMATION MARK HAIR HYPOPLASIA

TWISTS AND CURLS: PILI TORTI: The shaft is flattened and twisted at angles of about 180 with 4-5 twists at irregular intervals giving

it a spangled appearance in the reflected light. The affected hair is unable to resist stretching forces and breaks at the twists. The abnormality is most evident over the occipital and temporal regions. The inheritance is AUTOSOMAL DOMINANT. Starts in childhood and tends to improve after puberty. Associations include------- KP, Icthyosis, nail dystrophy, widely spaced teeth, enamel hypoplasia, corneal opacities, MR, Hypogonadism and deafness.

WOLLY HAIR: These are thightly coiled markedly curly hairs that do not form locks. The hairs are usually short probably due to shortened growth cycle. Hereditary wooly hair is a autosomal dominant trait that presents at birth and improves with age(sometimes associated with pili torti, teeth and eye defect, deafness, ichthyosis, KP ). A localized patch of wooly hair , wooly hair nevus has a linear epidermal nevus associated with it.

CIRCLE HAIR: A tightly coiled hair shaft gets embedded in the statum corneum. The condition is seen in middle aged over abdomen and bony prominence.

In KP and SCURVY, the coiled and corkscrew hairs are associated with follicular keratoses. CORKSCREW HAIR: The hair are thick and coiled into a double spiral that resembles a corkscrew.

UNRULY HAIR: These are hairs that are difficult to manage by combing. Causes are: CONGENITAL: Normal infants, Cornelia de lange syndrome, Down’s syndrome. Mental retardation, wooly hair,

pili torti. ACQUIRED: drug induced(etretinate, spironolactone), as a forrunner of androgenetic alopecia.

BANDS:

PILI ANNULATI: The hairs are fragile and appear banded in reflected light giving a sandy appearance. Scanning electron microscope reveals air filled spaces in the cortical portion .

BUBBLE HAIR: This a cosmetic abnormality caused by brief but rapid and focal heating of damp hair by a blow dryer. The affected hair breaks easily. Light microscope reveals bubbles within the hair shaft. Severe affection gives a banded appearance.

MENKES KINKY HAIR DISEASE: XLR Defect in copper metabolism. Copper is required in the formation of both melanin and cystine------- results in

alteration of keratinization and pigmentation of hair. The hair is normal at birth but after the shedding of first hair in infancy, the new hair that grow are light

colored, twisted and fragile with a STEEL HAIR APPEARANCE. The plasma copper and ceruloplasmin levels are reduced+ hair copper content is reduced. Other features:

mental and physical retardation progresive psychomotor retardation and hypotonia from the third month. Convulsions esp. myoclonic

jerks are common. Prone to hypothermia and infection Aneurysm and hemorrhage in internal organs Metaphysic of long bones have changes similar to scurvy.

POLIOSIS

It refers to circumscribed whitening of hair affecting a group of neighbouring hair follicles. Causes are:

GENETIC Isolated(autosomal dominant)PeibaldismTuberous sclerosisWaardenburg syndromeWoolf’s syndrome AUTOIMMUNEVitiligo Alopecia areataVogt- Koyanagi Harada syndrome INFLAMMATORYX-raysHerpes zoster EXOGENOUS CAUSESHydroquinoneHydrogen peroxide Monobenzyl ether of hydroquinone.

Waardenburg syndrome: perceptive deafness+ broad nasal root+ confluent eyebrows+ lateral displacement of medial canthi+ heterochromia irides+ poliosis+ hypopigmented macules.

Woolf’s syndrome: white forelock+ piebaldism + deafness

PREMATURE CANITIS

CAUSES: AutoimmuneGENETIC------- pernicious anemiaIsolated HypothyroidismProgeria HyperthyroidismWerner’s syndrome infectiveMyotonic dystrophy HIV infectionRothmund Thomson syndrome Drugs Ataxia telangiectasia Mephenesin,Flurobutyrophenon Chloroquin

CUTIS VERTICIS GYRATA It is a term applied to the hypertrophy and parallel or gyrate folds of the skin of the scalp. Biopsy findings include hypertrophy of the sebaceous glands but no excess collagen. Causes are----------

ISOLATED(AUTOSOMAL DOMINANT) HEREDITARY

Pachydermoperiostosis Neurofibromatosis Tuberous sclerosis Darier’s disease

ENDOCRINE

Acromegaly Myxedema Cretinism

INFLAMMATORY Dissecting cellulites of the scalp Chronic folliculitis

TRAUMATIC Traction

TUMOROUS Congenital melanocytic nevus Neurofibroma