Skin, the mirror of internal man is the largest organ of our body, consisting about 1.7m2 in surface area and 4 kg of body weight. it is the major interface between the man and his environment. Dermatology the science of skin disease is a visual clinical specialty.  
As far as homoeopathic physicians are concerned the study of skin diseases are very important, because skin is one of the most important site of action of our medicines. 

In repertory of homoeopathic materia medica by Dr. J.T.Kent we perceives numerous dermatological problems of which some are expressed in old terminologies, if we understood the exact meaning of these terms, it will be great help in the selection of exact similimum .In this work my intention is to investigate through the deeper aspect of skin in kent’s repertory.

FUNCTIONS OF SKIN:-
1) Protection against water loss (sc)
2) Protection against water gain.(sc)                 
3) Protection against penetration of toxic substances.
4) Protection against microbial attack.
5) Thermal regulation through heat loss, via
  (a) Sweat evaporation and
  (b) Vasomotor regulation.
6) Communication through sensory massage.
7) Immune function with a role in protection against foreign antigen.
8) Metabolic function with an important role in synthesis of Vit D after solar UV radiation.

CLASSIFICATION OF SKIN DISORDERS .
Skin disorders may either be generalised, affecting all part of the integument, localized to one or several sites. The site of abnormality is known as a lesion. Or they may be eruptive (exanthematic) in which large number of lesions appear spottily over the skin.

CLASSIFICATION BASED ON THE ELEMENTERY LESIONS: -
{1} MACULE.
    CONDITIONS: -
(a) Erythema.
(b) Rosacea.
(c) Lupus.
(d) Chloasma
(e) Xanthelasma.
(f) Syphilis.
(g) Purpura.
(h) Naevus.
(i) Lenigo Maligna.
(j) Leucoderma.
(k) Roseola.
{2} VESICLE.
CONDITIONS,
(a) Eczema.
(b) Erysipelas
(c) Herpes.
(d) Impetigo contagiosa.
(e) Erythema multiforme.
(f) Scabies.
(g) Sudamina.
(h) Varicella.
(i) Zoster.
{3} BULLA. 
CONDITIONS,
(a) Erysepelas.
(b) Leprosy.
(c) Pemphigus.
(d) Rupia.
{4} PUSTULE.
CONDITIONS,
(a) Acne.
(b) Ecthyma.
(c) Eczema.
(d) Furuncles.(Boils)
(e) Scabies.
(f) Sphilis.
(g) Variola.
(i) Dermatitis multiforme.
 {5} PAPULE.
CONDITIONS,
Acne
Erythema multiforme
Eczema
Lichen plannus
Lichen simplex
Lupus
Milium
Molluscum
Prurigo
Rubiola
Scabies
Syphilis
Urticaria
Variola 
{6} TUBERCLE
(a) Acne
(b) Fibroma
(c) Lentigo maligna
(d) Leprosy
(e) Lupus
(f) Syphilis
(g) Morphoea
{7} SCALES.
(a) Icthyiosis
(b) Pityriasis simplex
(c) Pityriasis Verscicolor
(d) Psoriasis
(e) Syphilis
(f) Tricophytosis capitis
(g) Eczema
(h) Lupus erythematosis

[1] MACULE
Localized lesion no more than discoloration of skin, with out any secretion, effusion, and change in thickness. It may be black from increase of pigment Or white from loss of pigment or red from congestion.
Rubric; In kents repertory we can't get the rubric macule so we can take
Skin, Discoloration, also in location chapters

Conditions:-
a) ERYTHEMA.
Rubric:-
Skin
Eruption, nodular,rosy(erythema)
Almost all conditions comes under immunologically mediated skin disorders.
E.g.:- Erythema multiforme
Erythema nodosum.

1) ERYTHEMA MULTIFORME.
An acute and relatively short lived inflammatory reaction of skin and mucosae occurring in response to a variety of antigenic stimuli resulting in scattered lesions in dermoepidermal junction
C/F :Red to purple macular papules some of which become annular: Face and upper limb commonly affected. Front of mouth is eroded and sloughy. Disorder starts acutely and usually over in less than two weeks. Etiology unknown. Disorder may be precipitated by infections like: Herpes simplex , coccidio mycosis, Histoplasmosis etc.

ERYTHEMA NODOSUM
A painful inflammatory disorder in which crops of tender nodules occurs in response to antigenic stimuli.
C/F: Individual lesions are red, raised and tender, varying in size from 1 to 3cm in diameter. Occurs in crops on shin, less common in forearm. Lesion takes two to six weeks to resolve. Disorder may be precipated by infections like : Tuberculosis, Sarcoidosis, Brucellosis, Leprosy.

B] CHLOASMA.
Macule is somewhat diffuse occurring in forehead and cheeks and is of brown colour. These changes in degree of pigmentation common in pregnancy. Dark areas appear symmetrically, across the cheeks ,around the eyes , over forehead giving a mask like appearance.
Rubric; no direct rubric.
We can take Face, Discoloration, brown spots
Forehead spots etc.

[C] XANTHELASMA.
Lesion appears as a papule around eyes, not associated with hyperlipidemia in 60-70 % of cases.
Rubric; Face eruption, lids on.

[D] ROSACEA (Rosy macule)
Is a chronic inflammatory lesions of face.Characterised by persistent erythema and talangectasia punctuated by acute episodes of swelling and papule. Papules are red, dome shaped and nontender in contrast to Acne. Common in cheek, forehead, nose and chin.
Rubric; Face,Eruption,Acne,rosacea.

[E] LUPUS VULGARIS.
Is a rare slowly progressive granulomatous plaque on skin caused by tubercle bacilli. Often has a thickened psoriasiform appearance but blanching with a glass slide will reveal gray green foci due to underlying granulomatous inflammation.(apple jelly nodules)
Rubric; Skin ,Lupus.

[F] SYPHILIS.
This disease caused by Trepanema pallidum. Reddish macule appearing in early syphilis chiefly on chest abdomen and back. Macule resembling those of leucoderma and met with about neck in young in early period.
In secondary syphilis there are wide spread macular rash in palm and later papular eruption.
Rubric; Skin ,Syphilitic
and also in concerned location chapters. 

[G] PURPURA.
Large macule or papule of blood under skin, which does not blanch on pressure. It is an immune complex disease caused by type III hypersensitivity reaction.
Histology shows vascularity involving small blood vessels
C/F :Purpuric rash on extensor surface of forearm,elbows,bottocks ,leg etc. Abdominal colic, vomiting,poly arthritis,polyarthralgia.
Representations of pupura are two types in Kent’s repertory
1] Purura miliaris and
2] Purpura sanilis.
1] PURPURA MILIARIS
Purpura associated with blockage of sweat glands. It is an inflammatory disease of disease of skin characterized by redness ,eruption, burning ,itching and release of sweat in abnormal ways(by eruption of vesicle) due to blockage of sweat gland.  
 2] PURPURA SANILIS
Chronic disorder of elderly old people above 70 yrs. Pruritic and ecchymotic spots occurs on extensor aspect of forearm which arise spontaneously after an unnoticed trauma.
Purpura is due to traction injury to small capillaries of dermis due to loss of dermal collagen and subcutaneous fat.
Rubric; Skin ,Purpura,sanilis.

H] NAEVUS.
Developmental anomalies consisting of immature melanocytes in abnormal number.
Two types congenital and acquired
Rubric; Skin, Naevus.

I] LENTIGO MALIGNA. (Hutchinson's freckle)
It is a slowly progressive premalignant disorder of melanocytes in which malignant melanoma often devolop.Occures in exposed part of face. Lesion is a pigmented macule with well-defined, rounded polycystic edges, which may up to 5cms diameter.
Rubric; Skin, Discoloration, liver spots,
Brown.

[J] LEUCODERMA.
White or light pink macules due to destruction of melanocytes.
Rubric; Skin, Discoloration ,pale.

[K] ROSEOLA (Skin eruption without catarrh)

This condition occurs in epidemic form. Eruption preceded febrile symptoms. The rashes are rose in color. When not in epidemic form cause is derangement of digestive system.
Other causes;
Sudden changes in temperature
Violent exercise,
Taking cold when over heated.
Two types Idiopathic and Symptomatic
Idiopathic form seen in infants
In Symptomatic erythema develop in the course of acute disease.
Rubric; Skin, Eruption, roseola.

2] VESICLE
Circumscribed elevation of skin < o.5 cm diameter containg fluid. It is a small elevation of hoary layer of epidermis.
Rubric; Skin, eruption, vesicle.

CONDITIONS: -
[A] ECZEMA (DERMATITIS)
A group of disorder characterized by the process of inflammation of the skin in which the main focus of damage is in the epidermis.
Causes: -
Direct injury from toxic substances,
Mechanical trauma,
Immunological reactions.
Common verities of eczema
a) Atopic dermatitis,
b) Seborrhic dermatitis,
c) Descoid eczema,etc.
     
INTERTRIGO
In some cases the exudation may not be abundant enough to raise the epidermis in to vesicle, but only loosens it, and the epidermis actually thrown off leaving a raw, moist surface called Intertrigo.
Rubric; skin,Intertrigo.

[B] ERYSEPELAS.
Acute febrile disease characterized by peculiar infection of the skin with enlargement of lymph nodes Caused by Beta heamolytic streptococci.
C/F :Sudden onset of a well marginated painful and swollen erythematous area usually of face and lower limbs. Phlegmonous erysipelas affects the skin in its Whole thickness and subcutaneous cellular tissue.
Rubric: - skin, erysipelas

[C] HERPES
Vesicular eruption mainly caused by viral infection like Herpes zoster,herpes simplex, chicken pox etc.
Rubric; Skin, eruption,Herpatic.
1) HERPES ZOSTER.
Caused by DNA virus. Mostly affects immunocompramised patients. This condition is due to reactivation of virus that has been sitting latent in a posterior root ganglion of spinal nerves.
If some one with out immunity to chicken pox contact with patient having shingles that may will develop chicken pox.
C/F :Paresthesia and pain in the distribution of one or more dermatomes.
Common sites;
Branches of trigeminal nerve.
Rubric;
Skin, eruption, Herpetic, Zoster.
2) VARICELLA (chicken pox)
Rubric; Skin, eruption, chicken pox.
3) HERPES SIMPLEX
Caused by DNA virus, two antigenic varieties, Type I & II.
Type I mainly affects face and oropharynx.
Type II affects genitalia.
Rubric; Type I . Face, eruption, herpetic, lips about.
Type II Genitalia eruption, penis, vesicle.

[D] RING WORM (TINEA INFECTION)
It is a dermatophytic infection. Three groups are there,
a) Trichophyton,
b) Epidermophyton,
c) Microsporon.    
C/F Based on the site affected tinea is classified under several headings
a) Tinea corporis. Tinea of the body and limbs. Pruritic red round well-marginated patches are seen at the site affected
b) Tinea cruris or groin ringworm.
Common in young men, well defined itchy, red, scaling patches occurring asymmetrically on the medial aspect of both groin.
c) Tinea pedis ,Affects feet. 
d) Tinea mannum,This variety is less common affects one palm.Palm red and dry with silvery scales.
e) Tinea capitis,Affects scalp, pink scaly patches on the scalp.
f) Tinea ungium,Affects nail plate and nail bed, frequent in finger nail than toe nail.
   Rubric; Skin,eruption,herpetic,circinate.

E] IMPETIGO CONTAGIOSA
It is a contagious superficial skin infection caused by staphylo coccus aurius. Mostly a disorder of pre pubertal children. Characterised by mild pyrexial symptoms followed by one or more vesicle ,this slowly enlarge , but soon dry in to thin light yellow scabs.
Rubric; Skin, eruption, impetigo.

F] SCABIES.
Due to infection with human scabies mite [acarus-hominis or sarcoptus scabie] an obligate parasite. Female parasite lives in the stratum corneum. Severe itching and characteristic eczematous rash caused by the invasion of mite. As a result of the affected individual become sensitive to the waste product of mite.
C/F :Intense itching, vesicles are seen but excoriation are much more frequently observed. Prurigo like papule Scaling etc.
Common sites; Palm,interdigital area of fingers,fluxeral creases, elbows etc.
Rubric; Skin, eruption, scabies.
Extremities, Eruption, elbow, bends of scabies
Extremities, eruption, knee, hollow of scabies.
 
G] SUDAMINA
Little round vesicle, produced by distension of the cutis by sweat ,and therefore seated at the orifices of sweat follicle When the vesicle may be attended with inflammation termed as miliaria. Prickly heat is likewise a miliaria.              
Rubric; Skin, eruption, vesicle, sudamina.
3] BULLA
Circumscribed elevation of skin > 0.5 cm diameter containg fluid.
Erysipelas 
Rubric; Erysipelas.
b) LEPROSY
Caused by mycobacterium lepre large bullae are seen usually solitary
Disease manifest in three forms Macular, tubercular and anesthetic.
In Macular there is brownish discoloration of various size and number.
In tubercular form development of tubercle in various parts of body. In anesthetic form bullae develop usually solitary persists for short time leaves behind discoloration and becomes anesthetic.

c) PEMPHIGUS (Pompolyx)
In this type of diseases blistering is due to Loosening of desmosal links between epidermal cells caused by immunological attack.
There are several types important one is Pemphigus vulgaris, lesions are thin walled delicate blisters usually rapidly ruptures and erode.
Rubric; Skin, eruption, pemphigus.     

d) RUPIA: -
Late malignant manifestation of syphilis. Bullai containing purulant,reddish mater which gradually dries up and form thick dark crusts underneath the crust, matter continues to form which again dries up and consequently raise the center.
Rubric; Skin ,eruption,rupia.

PUSTULE
An elevation of epidermis by purulent exudation.

a) ACNE
One of the commonest skin disorders. It is a disorder of hair bearing skin in which hair follicle develop obstructing horny plugs( comidones) as a result of which inflammation later develop around the obstructed air follicle, causing  tissue destruction and scar formation. Earliest feature of the disorder is increased rate of sebum secretion making the skin greasy.
Rubric; Face, eruption, Acne.
b) ECTHYMA
Isolated large pustule up on a red swollen surface. Pustule develops in to the size of a pea. Seen in extremities, on the seat, chest, neck etc.
In tropical and subtropical areas impetigo like disorder is spread by flies and bite of arthropods. This is more destructive and produce deeper, oozing and crusted sores and is caused by Beta haemolytic streptococci
Rubric; Skin, eruption, ecthyma.
c) FURUNCLES (Boil)
                    Infection of the hair follicle caused by staphylococcal aurious.
CARBUNCLE; It is large 3-4 cms diameter and represent infection of hair follicles.
Rubric: - Skin, eruption, boil.
d) ECZEMA;  
Rubric; Skin, eruption, eczema.
PAPULE
Small solid elevation of the skin <0.5 cm diameter.
a) Acne
b) Erythema multiforme.
c) Eczema.
d) Lichen plannus.

LICHEN PLANNUS.
Inflammatory disorder of skin of unknown origin but with an immunopathogenic component. It is characterized by eruption of variable extent by typical mauve or pink flat topped itchy papule.
Common sites,
Front of the wrist,
Skin of lower limb, trunk, and mucosae are affected in 30 % (mouth)
Rubric; Chest,eruption,like ,lichen plannus.

LICHEN SIMPLEX.
This is a disorder localized to one or more sites. It is characterized by intense pruritus and exaggerated skin markings.
Sites; Medial aspect of the ankle, back of scalp, extensor ascept of wrist and forearm.
Seen in tense anxious middle-aged subjects.
Rubric; Chest, eruption, like lichen plannus.

LUPUS.
Skin, eruption,lupus.

 MILIUM
Affection characterized by the appearance of minute white or pearly papule.
It is usually clustered about the eyes, upper and lower eye lid. Common in women.
Rubric; no direct rubric.
Eye, eruption, lids on.

MOLLUSCUM CONTAGIOSM
Common infection of skin caused by virus of the poxvirus group. Pink or skin colored umbulicated papule.
Rubric; no direct rubric.
 
PRURIGO
Flat papule, which have same color of surrounding skin. When broken they discharge a small drop of clear fluid with intense itching.
Aetiology; want of personal hygiene.

RUBIOLA (MEASLES)
Red papule covering the entire surface of skin and accompanied with febrile symptoms.
Rubric;Skin;eruption,measles.
 SYPHILIS
Generalized reddish or copper coloured, may degenerate in to pustule.

URTICARIA (NETTLE RASH, WHEAL)
Common disorder occurs as a result of histamine release from mast cells in the skin and are often, though not invariably, caused by allergic hypersensitivity. Type 1 hypersensitivity Reaction.
C/F
Itchy red papule and plaque of variable size
Rubric; Skin,eruption ,urticaria
VERIETIES;
1) COLD URTICARIA
After exposure to cold.
Rubric; Urticaria, cold air in,
Cold bath after.
2) PRESSURE URTICARIA
After pressure on skin.
Rubric; Urticaria, scratching after.
3) DERMOGRAPHISM
Urticaria mark when skin is rubbed firmly.
 Rubric; Urticaria, scratching after.
4) SOLAR URTICARIA
When exposure to sun.
Rubric; Urticaria, sun exposure to.
5) CHOLINERGIC URTICARIA
Irritation small urticarial spots develop after exercise or hot bath.
Stimuli that evoke sweating from the postganglionic cholinegically enervated sweat glands
Rubric; Urticaria, warmth and exercise
Excessive violent after.

TUBERCLE
Solid elevation of skin larger than papule.
a) Acne
b) Fibroma
Tumors of varied size and form which takes their origin from dermal or sub dermal tissues which are single or multiple.
Rubric; Skin, indutarion, nodules etc.
c) Lentigo maligna
d) Leprosy
Reddish brown tubercle on the forehead, ear etc.
Rubric; Skin, eruption, tubercle, lepros.
e) Lupus; Solitary or few reddish brown tubercles terminate by ulceration.
f) Syphilis
Copper coloured tubercle terminating with suppuration, in early syphilis lesions are numerous, in late syphilis number of lesions are limited.
Rubric; Skin, eruption, tubercle, syphilitic.
g) Morphoea;
It is localized scleroderma,a chronic cutaneous affection, characterized by appearance of one or more discrete spots or patches, usually isolated and round in form. It is pink in colour and slightly elevated when hyperaemic and hypertrophied later become whitish ,anaemic,atrophic and depressed.
Pathology; Generalized replacement of the subcutaneous fat with new collagen, which has pale homogeneous appearance. Belong to immunologically mediated skin diseases.

SCALES
Collection of cell of stratum corneum, due to disturbances in the formation of stratum corneum.(keratinisation)
When scales are small in size and loosely attached ,like a fine powder or meal scattered over surface called Farinaceous.
When scales are large ,thick ,heaped up and firmly attached called   Farinaceous.
CONDITIONS;
a) Icthyosis
The word derived from Greek word Icthyos that means fish.
It is a generalized non inflammatory disorder of keratinisation and implies a congenital origin
Skin is rough and dry covered with thickened and exfoliating cuticle like scales.
Rubric; Skin, eruption, scaly.
b) Pityriasis verscicolar
Caused by yiest like micro organism Pityrio sporum ovale (malazezia fur fur). It is common in young adults. It causes brownish slightly scaly macules over front and back of upper trunk. In dark skined individuals lesions are hypo pigmented.
Rubric; Skin ,eruption, scaly.
c) Psoriasis
Common genetically determined inflammatory skin disorder of unknown origin.Charecterised by well demarcated raised scaly patches,localised to extensor surface.affction commences in small red somewhat red elevated roundish spots like drops covered by dry oblong white scales called - Psoriasis guttata.
When the spots are increasing in number, they coalesces to form large irregular surface, which covered with scales of various thickness and adhesiveness called - Psoriasis diffusa.
They some times accumulate in round patches, while on the periphery new spots still appear, and those in the center dries up give rise to circular eruption called  - Psoriasis annulata.
Several such circles join together, their peripheral line broken off by already healed of center and now they forms various figures, parts of circle ,straight line etc. called - Psoriasis gyrata.
In some cases the morbid process continue for a long time and
Causes skin to become thickened, rigid and cracked,this takes places in diffuse irregular forms called - Psoriasis inveterta.
These names do not indicate different verities but form and stages of same cutaneous manifestation.
Rubric; Skin, eruption, psoriasis.
 
Old terminologies used in skin chapter;
Pocks; Skin, eruption, pocks.
It is a pustule in the eruptive disease. (Smallpox)
Scarletina; Acute infectious and contagious disease characterized by diffuse scarlet eruption.
Gritty; Skin, eruption, gritty.
Eruptions like hard sharp granules as if sand.
Coppery; Reddish
              Blotches; Term to denote pigmented or erythematous lesions
Phagedenic; An ulcer that rapidly spreads peripherally destroying the tissues as it increase in size.
 
References:
RAUES PATHOLOGY
SKIN DISEASES BY DOUGLAS
ROXBERGH'S COMMON SKIN DISEASES BY RONALD MARKS