Science in general and medicine in particular made truly momentous advances during the last century. Dermatology too benefited from many of these and underwent some additional ones of its own. The epochal general scientific events of this period paved the way for the likely future of dermatology. As a branch of internal medicine, dermatology has come a long way since its days of infancy in the early 18th century. Dermatology is the study of skin diseases and conditions. A dermatologist treats disorders relating to the skin, hair and nails. His domain of knowledge include areas like, clinical research, contact dermatitis, cosmetic dermatology, connective tissue diseases, disease of hair, disease of nails, dermatitis and eczema, erythema, environmental dermatology, geriatric dermatology, genodermatosis, histopathology and electron microscopy, immunology, leprosy, occupational parasitology, eruption, dermatoses, papulosquamous pigmentation, paediatric dermatology, photobiology, skin signs in systemic disease, tumours and melanomas, virology, bacteriology, venereal diseases, vesiculobullous eruption, dermatosurgery and laser surgery, clinical dermatology, dermatopathology and mycology.
Advances in dermatology:
Before the turn of millennium i.e. in the 20th century, the world of science has seen a sea change in the field of technological advancement. The focus of research suddenly changed from the ‘Space’ to ‘Space Within’ and from purity of discipline to a healthy amalgamation of all. Dermatology has benefited greatly from the progress made in the following fields: Cellular biology: Revelation of biology of the cells of the epidermis and its junction with the dermis proved to be a major advance in understanding the cutaneous pathology in general and pathogenesis of bullous disorders in particular. Immunohisto-pathological (including prenatal), electron microscopic and immunofluorescence advances in the later part of the 20th century enabled accurate subtyping. Consequently, it enabled early appropriate management, genetic counselling and DNA based prenatal diagnosis for subsequent pregnancies of epidermolysis bullosa (EB), a group of inherited disorders with blistering of skin and mucous membranes after trivial trauma having diverse prognoses. Direct immunofluorescence (DIF) of mucosal pemphigus vulgaris (PV) and demonstration of specific antigens by immunoblotting, etc. led to its early specific diagnosis and improved prognosis. The blisters of staphylococcal scalded skin syndrome (SSSS) as well as pemphigus foliaceous were shown to be due to disrupted adhesive function of desmoglein 1 (Dsg 1) by exfoliative toxin or anti-Dsg1 immunoglobulin G respectively. Topical corticosteroids: The discovery of compound E (cortisone) in 1935 heralded the arrival of topical corticosteroids. Numerous modifications of the corticosteroid molecule, viz. halogenation, esterification, hydroxylation, modification of side chains etc. and improvements in delivery systems have since significantly increased its anti-inflammatory activity as well as adverse effects. Discontinuation after prolonged use of a potent steroid on the face or anogenital region can lead to a rash that subsides on their re-use and promptly recurs on discontinuance, hence getting the patient ‘addicted’ (topical steroid addiction syndrome). Tachyphylaxis and disguised morphology of nonsteroid responsive dermatoses (scabies, tinea, etc.) can also result from their chronic use. Superficial fungal infections: Griseofulvin, originally isolated from Penicillium griseofulvum was the first oral drug to be used during the second half of the 20th century to treat dermatophytosis, a superficial fungal infection with the potential of troubling the active and the obese all the year round particularly in the tropics. Candida albicans, the opportunistic ‘marker’ of
immunosuppression was initially tamed by nystatin. The antifungal spectrum broadened subsequently with the arrival of azoles (ketoconazole, fluconazole, itraconazole, etc.) and more recently allylamines.
Phototherapy: Although the Greeks were the first to use sun as a therapeutic light source 3,000 years ago, modern heliotherapy began in 1923 with the use of UVB in psoriasis. PUVA, acronym for oral psoralen followed by long-wave ultra violet light (UVA), got FDA approval for psoriasis in 1982. It has also been used therapeutically (vitiligo, mycosis fungoides, atopic dermatitis. generalised lichen planus, urticaria pigmentosa, pityriasis rubra pilaris, etc.) and prophylactically (polymorphic light eruption, solar urticaria, chronic actinic dermatitis, etc.) for many chronic dermatoses. Narrow band UVB at 311 nm, due to reduced risk of carcinogenicity compared to PUVA and more efficient clearing of psoriasis with reduced erythema compared to broadband UVB was a natural corollary.
Photodynamic therapy (PDT) sought to inactivate tumoural or aberrant psoriatic cells by generating highly reactive oxygen intermediates by exposing, after prior systemic or topical administration of a photosensitiser, to long wavelength emission of a visible or a laser light. In photophoresis, two hours after psorelen intake, blood is centrifuged to separate its lymphocyte-enriched fraction which after being exposed to UVA, is then returned to the patient whose immune system responds by destroying the altered or damaged malignant T lymphocytes. This mode of therapy is quite useful in Sezary syndrome, less so in systemic sclerosis and GVHD and is least effective in psoriasis, atopic dermatitis, pemphigus, SLE, etc. Retinoid: Vitamin A (retinol) was extracted from egg yolk in 1909. Retinoids, its structural analogues, result naturally during vitamin A metabolism but most (more than 1500 since 1968) are synthesised by changing the polar end group, polyene side chain, or cyclic group of vitamin A. Vitamin A as well as retinoids affect epithelial tissue differentiation, general growth, visual function and reproduction. They act on cells as hormones by binding to retinoic acid receptors (RAR) and/or other retinoid X receptors (RXR), which have a, b and g subtypes. Topical (tretinoin, tazarotene and alitretinoin) as well as oral
(isotretinoin and acitretin) retinoids are available for dermatological use. However, FDA approved only for acne, sun-induced skin aging and psoriasis, topical retinoids have also been used for flat warts, epidermal naevi, porokeratosis, melasma, keloids, scars, etc. Adapalene, a naphthoic acid derivative, also has a retinoid-like action but causes much less local irritation. Oral isotretinoin, though FDA approved only as a second line drug for severe recalcitrant cystic or nodular acne vulgaris, is the drug of choice for pityriasis rubra pilaris, severe lichen planus, Darier’s disease and ichthyoses. It has also been found beneficial in oncology in combination with other agents such as cytokines. Likewise, acitretin has been used for many other dermatoses besides the FDA approved one of severe recalcitrant psoriasis. Dermatosurgery: In 1936, Dr. Frederic Mohs of the University of Wisconsin developed Mohs ‘chemosurgery’, a technique to remove cancers with maximum tissue conservation providing controlled, serial microscopic examination by frozen section of the excised tissue that had been directly fixed chemically applying zinc chloride paste. Subsequently, use of frozen sections of fresh tissue eliminated the need of zinc chloride paste. This technique is especially effective on basal cell and squamous cell carcinomas of the face and recurrent skin cancers. The therapy of resistant vitiligo was revolutionised by grafting viz. Thiersch’s grafts, epidermal grafts (by suction of freezing blisters) and minigrafting by punch. More and more procedures like nail surgery, single hair transplantation, dermabrasion. laser surgery, etc. are being increasingly carried out by the dermatologists.