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Tuberculosis (TB) is a contagious disease caused by mycobacterium tuberculosis. When this bacillus is stained with carbol fuchsin it appears purplish red. The bacterium retains this dye even when it is washed with acid and alcohol. That is why it is called acid fast bacillus (AFB). Mycobacterium tuberculosis can remain dormant for many years in the lung without producing disease. Continue reading
Chest skiagram
The radiological opacities in a chest x-ray are a result of the pathological processes taking place in the lungs. TB causes alveolar consolidation, necrosis, cavitation and fibrosis, features, which it shares with a variety of lung diseases. That is why TB also shares its radiological features with many other pulmonary diseases.
Hence, there is no radiological feature that is absolutely typical of pulmonary TB and other diseases may mimic TB radiologically. The following features, however, when seen on a chest skiagram, suggest a diagnosis of TB: Continue reading
Psoriasis can start at almost any age and involves both the sexes equally. It manifests in a variety of forms.
The most frequent manifestation is called plaque type psoriasis where the lesions characteristically consist of well demarcated erythematous plaques covered with loosely adherent silvery scales, the silvery colour of the scales becoming more prominent when attempts are made to scrape them off.
The lesions vary in shape and size and with peripheral extension some lesions may coalesce to form large gyrate or geographical patterns. Extensor aspects of the extremities, particularly the elbows and the knees, the sacral region of the back and the scalp are the usual sites. Scalp involvement is rare in children. Continue reading
This is a group of disorders in which there is complete absence of melanin pigmentation in the skin and eyes. If the defect is in eyes and skin both it is known as oculo-cutaneous albinism. If it is in the eyes alon, it is caled ocular albinism. There are ten types of OCA and 4 types of OA.
All the types have normal numbers of melanocytes but cannot produce melanin because of an enzyme defect. Continue reading
Some plants contain chemicals which can sensitise the skin to sunlight. If an individual comes in contact with such a plant and simultaneously gets exposed to sunlight, he is likely to develop hyperpigmentation in the areas exposed to the plant and the sunlight.
As a rule, there are no signs of inflammation, but occasionally the patient may develop blisters as well. A similar picture can also be produced if the patient gets exposed to perfumes used as such or present in cosmetics, or similar compounds present in the purified extracts of plants, and oils used for hair or skin. Continue reading
Some patients develop asymptomatic, pin-point, hyperpigmented macular lesions which appear on any part of the body irrespective of whether the area is exposed to sunlight or not. Some lesions may remain discrete, but most of them coalesce with each other to form large irregular areas of hyperpigmentation.
On the forearms and legs the pigmentation commonly occurs around the hair follicles. New lesions keep on appearing for a few weeks or even a few months and then these lesions tend to disappear spontaneously over the next several months or may even take a few years.
The cause of this disease is not known. It seems to represent a post-inflammatory hyperpigmentation initiated by a substance which reaches the skin via blood. Till the exact aetiopathogenesis is known, it is best to call this disease idiopathic guttate and confluent hypermelanosis.
Treatment
Since the cause of this disease is not known, its treatment is also empirical. If the new lesions continue to appear, the patient should be treated with systemic corticosteroids in a dose of 10 to 20 mg of prednisolone a day. This dose given over a period of four to six weeks has been observed to prevent the appearance of new lesions. Then the dose of corticosteroids can be gradually reduced by 5 mg every 1-2 weeks.
The hyperpigmented lesions tend to disappear spontaneously in the course of an year or so, but this period can presumably be shortened by local massage with keratolytic agents, or retinoic acid, hydroquinone and fluocinolone acetonide ointments massaged one after the other at night. Vitamin C in a dose of 2.5 gm twice a day may also be given.
Pityriasis rosea is an acute, self-limiting skin eruption with a distinctive and constant course, with an initial lesions that is a primary plaque that is followed after 1 or 2 weeks by a generalized secondary rash with a typical distribution and lasting for about 6 weeks
This is common among adolescents and young adults and manifests as a sudden eruption of asymptomatic, oval or circular, erythematous and scaly lesions.
The margins of the lesions are more prominent and pink, while their central parts are depressed and covered with fine bran-like scales. The lesions are distributed on the upper trunk and the arms and give the impression of being distributed along the lines of the ribs. Continue reading
Colour of the skin is constituted by three components:
Melanin constitutes the chief pigment and is produced from the amino acid tyrosine by the action of a copper containing enzyme called tyrosinase. This enzyme converts tyrosine into dihydroxyphenylalanine (DOPA) which is further converted to dopaquinone by the same enzyme. Continue reading
This is also called melasma or seborrhoeic melanosis and consist of asymptomatic, very superficial-looking macular areas of brownish pigmentation.
The skin does not show any other changes. The lesions are usually located the bridge of the nose, both the cheeks, the upper lip and the forehead. On the forehead, a linear area just above the eyebrows is frequently involved, while an area of the upper lip below the nose and skin around the eyes are as a rule spared. Continue reading
A mild attack of urticaria can be easily controlled with oral antihistamine drugs given orally or by an intramuscular injection.
If the attack is severe and generalized, intramuscular antihistamines may be used and then replaced by oral antihistamines.
Once the urticarial attacks have been controlled, the antihistamines can be withdrawn gradually.
An attack of angio-oedema involving the lip or the tongue must be treated as an emergency with 0.5 ml of 1:1000 adrenaline subcutaneously if it threatens to spread inside. Continue reading
