Trophic tissue disorders
These changes are directly related to impaired peripheral blood supply and nutrition. The most striking acute form is pressure ulcers (decubitus). They are areas of soft tissue necrosis typical of bedridden patients. Pressure ulcers form where the skin is constantly compressed: on the sacrum, elbows, and heels. The pathology develops in stages: first, an area of hyperemia appears, which gradually transforms into an erosion, and then into a deep ulcer and necrosis.
Chronic peripheral nutritional disorders manifest as dry skin, localized hair loss (alopecia), and poor regenerative capacity. Over time, trophic ulcers form, potentially progressing to gangrene. The main causes are arterial and venous insufficiency, as well as peripheral neuropathy (most frequently associated with diabetes mellitus and macroangiopathy).
Scars and deformations as diagnostic clues
Inspecting scars allows for gathering a patient's unvoiced medical history. Ordinary postoperative scars indicate the drainage of abscesses or tumor removal. However, specific morphology provides more information:
- "Stellate" scars indicate healed fistulas.
- Scars on the neck often remain after tuberculous lymphadenitis (caseous necrosis with the formation of a long-term non-healing fistula).
- Multiple minor burns in practice often result from domestic trauma associated with alcohol abuse.
Of particular diagnostic significance is Dupuytren's contracture. This is a severe cicatricial degeneration of the palmar aponeurosis and finger tendons that blocks extension movements (the little finger is frequently affected). It is a classic marker of chronic alcoholism, although it requires differentiation from the consequences of injuries. The physician must also pay attention to artificial alterations, such as tattoos. Their presence dictates vigilance regarding blood-borne infections (HIV, hepatitis B and C).
Vascular and metabolic skin signs
The skin acts as a screen reflecting systemic pathologies and metabolic failures:
- Mottled skin (livedo). It manifests as a translucent reticular or arborizing bluish coloration, typically on the extremities upon cooling. It occurs due to blood stasis and venular microthrombosis. This is an important sign of systemic lupus erythematosus, dermatomyositis, antiphospholipid syndrome, as well as tuberculosis and malaria.
- Markers of dyslipidemia. Excess lipids are deposited in phagocytes, forming xanthomas (nodular thickenings over joints and Achilles tendons) and xanthelasmas (yellow plaques on the eyelids). They indicate atherosclerosis or primary biliary cholangitis.
- Markers of gout. Purine metabolism disorders lead to the deposition of uric acid crystals in the form of tophi—dense, nodular tophi on the ears and around joints.
- Markers of liver pathology. Chronic liver diseases and cirrhosis are often accompanied by the appearance of "spider angiomas" (telangiectasias)—focal capillary dilations.
Manifestations of drug hypersensitivity
Skin reactions to medications can range from mild discomfort to life-threatening conditions:
- Erythema. They can be fixed or present as erythema multiforme (polymorphic rings on extensor surfaces accompanied by fever). The most severe forms are Stevens-Johnson syndrome and toxic epidermal necrolysis (Lyell syndrome), which cause acute massive necrosis of the epidermis and mucous membranes with the formation of large bullae.
- Urticarial reactions (hives). Sudden appearance of pruritic wheals surrounded by a hyperemic zone.
- Angioedema (angioneurotic edema). Rapidly developing edema of subcutaneous tissue and mucous membranes. Extremely dangerous when localized in the larynx due to the risk of asphyxia.
- Photosensitization. Severe inflammation developing on exposed skin areas under the influence of sunlight, which is typical for the use of certain antibiotics and fluoroquinolones.
Briefly: answers to topical questions
Which drug classes, besides antibiotics and fluoroquinolones, frequently cause photosensitization?
Besides antibiotics and fluoroquinolones, photosensitization is associated with:
- Amiodarone (antiarrhythmic agent) — prolonged use may cause hypersensitivity to light.
- Drugs that induce 5-aminolevulinic acid synthase synthesis — cause drug-induced porphyrias; in this process, porphyrinogens turn into porphyrins when exposed to light, reacting with oxygen to form active radicals that damage skin cells.
Disease markers starting with the letter "K" (C in English): Xanthomas/Xanthelasmas — cholesterol, Dupuytren's contracture — alcohol, Anticardiolipin antibodies — thrombosis.
Class and exam questions
What does a reticular bluish pattern on the skin of the extremities indicate?
This is the livedo phenomenon (mottled skin). It indicates venular microthrombosis and venous stasis, often occurring in systemic connective tissue diseases, Sneddon's syndrome, and antiphospholipid syndrome.
Why is it important to look for Dupuytren's contracture and burn scars during the examination?
These changes, especially their combination, are classic markers of chronic alcohol abuse. The contracture occurs due to fibrosis of the palmar aponeurosis, and burns are a consequence of domestic trauma while intoxicated.
What is the danger of drug-induced urticarial reactions?
Urticaria itself causes only itching and discomfort, but it is often accompanied by angioedema (angioneurotic edema), which, when localized on the tongue, in the pharynx or larynx, leads to life-threatening asphyxia.
What else to study on this topic
- Mechanisms of caseous necrosis and fistula formation in tuberculous lymphadenitis.
- Pathogenesis of microcirculatory thrombosis in antiphospholipid syndrome.
- Differential diagnosis of emergency conditions: Stevens-Johnson and Lyell syndromes.
- Association of primary biliary cholangitis with lipid metabolism disorders and xanthomatosis.
- Features of eye examination for detecting corneal arcus senilis.
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