Questions and Answers
What is the average thickness of the epidermis?
Which layer of the epidermis is composed of dead keratinized cells?
What function does filaggrin serve in the stratum granulosum?
Which layer of the epidermis is found primarily in acral areas?
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What process occurs every 28 days regarding skin cells?
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Which type of skin cell is primarily responsible for keratin production?
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What percentage of an average adult's body weight is made up by skin?
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What is a characteristic feature of the stratum spinosum?
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What is the primary purpose of hair in relation to social interactions?
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Which of the following factors is known to increase hair growth rate and diameter?
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What structure within the hair is primarily responsible for maintaining fiber integrity?
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How many lifetime cycles can a hair follicle go through?
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Which phase of the hair cycle is characterized by hair shaft shedding?
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What is the primary function of melanocytes in the skin?
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Which cells are primarily involved in capturing and presenting antigens for immune response?
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Merkel cells are primarily associated with which function in the skin?
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What is the main structural protein found in the dermis?
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What characterizes the reticular dermis?
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What condition is caused by the destruction of melanocytes?
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Anetoderma is primarily associated with the loss of which type of tissue?
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What is the primary cell type found within the dermis?
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What is the primary characteristic of lanugo hair?
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Which type of hair undergoes a full hair cycle but is shorter than terminal hair?
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Which condition is characterized by excessive and diffuse shedding of hair?
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What is the primary cause of Alopecia Areata?
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Where are sebaceous glands most commonly found?
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Which of the following areas does not contain sebaceous follicles?
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What is the primary cause of acne vulgaris?
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Which area of the body has the highest density of eccrine sweat glands?
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What type of rash is most commonly associated with miliaria rubra?
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What is the primary secretory unit of eccrine glands composed of?
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What prevents sweating by acting on acetylcholine release?
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How much sweat can a person produce under maximal stimulation within an hour?
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What locations are primarily associated with the presence of apocrine glands?
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What is the nature of the secretion produced by apocrine glands?
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What physiological mechanism primarily stimulates the secretion of apocrine glands?
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What distinguishes apocrine secretion from other types of glandular secretion?
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What condition is characterized by intense itching around the skin areas with apocrine glands?
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Which part of the nail serves as a protection against pathogens and trauma?
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What is the shape and characteristic of the nail plate?
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Where is the lunula located on the nail?
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What is the primary function of the superficial vascular plexus in the skin?
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Which of the following is a characteristic feature of port-wine stains?
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What causes venous ulcers?
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Which condition involves benign growths made up of extra blood vessels?
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What is a primary function of the hypodermis layer of the skin?
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Which type of skin condition might involve inflammation of the panniculus?
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How does the vascular system contribute to temperature regulation in the skin?
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Which statement is true regarding disorders associated with skin vasculature?
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Which of the following aspects relates to the history of present illness in dermatology?
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Which of the following factors can exacerbate skin conditions according to the history-taking process?
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In medical history, which condition is most commonly associated with skin manifestations?
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What should be included in the medication history when taking a dermatological history?
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Which of the following is not typically assessed in the social history during dermatological evaluations?
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Which system is reviewed to gather comprehensive information about symptoms potentially related to skin conditions?
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Which is a common factor to consider under family history related to skin diseases?
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What scale is commonly used to assess the severity of skin problems?
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Which condition is a clear indication for a total body skin exam?
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What can subjective symptoms indicate in a skin examination?
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What is essential for a successful skin examination?
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In which area should hair examination include assessments?
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Which characteristic is examined when evaluating nails?
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What can modify the appearance of skin lesions?
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Which physical sign should be observed during a skin examination?
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What should be done before taking photomicrographs during a skin examination?
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Which of the following signs indicates potential liver problems?
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What dermatological condition is characterized by crusts in the nasal area?
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Which examination is rarely performed but may be indicated for nail complaints?
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Swollen joints may indicate which of the following conditions?
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What condition is suggested by dry lips potentially linked to Isotretinoin use?
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Which area is the common site for contact dermatitis and fungal infections?
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Which skin condition is characterized by sunburn and photoallergic contact dermatitis?
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Enlarged and congested tonsils may lead to which dermatological issues?
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What is the primary function of potassium hydroxide (KOH) in the preparation of scaling skin lesions?
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Which fungi form is specifically identified by the KOH preparation technique in cases of tinea versicolor?
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What indicates the possible presence of herpes simplex virus (HSV) or varicella-zoster virus (VZV) in a Tzanck smear?
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What is the first step in preparing a skin lesion sample for a Tzanck smear?
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How is the sample treated before being viewed under a microscope after scraping in KOH preparation?
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What must be performed to identify the specific virus in a sample with suspected HSV or VZV after a Tzanck smear?
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Study Notes
Dermatology Overview
- Dermatology focuses on diagnosing and treating skin diseases, including conditions of hair and nails.
- Involves cosmetic medications and procedures.
Skin Facts
- Average adult has approximately 1.75 m² (18.5 ft²) of skin, accounting for about 16% of body weight.
- Skin thickness varies: thickest on soles (1.4 mm) and thinnest on eyelids (0.2 mm).
- Skin renews every 28 days, shedding around 30,000-40,000 dead skin cells per minute.
- Natural skin hosts bacteria, fungi, and viruses. Changes in skin can reflect internal health issues.
Basic Anatomy of the Skin
Epidermis
- The outermost skin layer, averaging 50 microns in thickness, with cells migrating from the base to the surface over 28 days.
Layers of Epidermis
- Stratum Corneum: Composed of dead keratinocytes; serves as a protective barrier against trauma and infections.
- Stratum Lucidum: Present only in acral areas and under conditions of excessive friction or trauma.
- Stratum Granulosum: Contains filaggrin, essential for skin barrier function; lipids here retain moisture.
- Stratum Spinosum: The bulk of the epidermis, featuring a spiny appearance from desmosomes, providing structural integrity.
- Stratum Basale: Contains epidermal stem cells responsible for cell division; located above the Dermo-Epidermal Junction.
Cells of the Epidermis
- Keratinocytes: Major cell type in the epidermis, connected by desmosomes, and responsible for producing keratin that provides strength.
- Psoriasis: A skin condition marked by abnormal keratinocyte proliferation, shortening the cell cycle to 3-7 days.
Melanocytes
- Located in the basal layer of the epidermis.
- Synthesize melanin to absorb and block UV light.
- Melanosomes are organelles forming melanin, responsible for skin color.
- Vitiligo is an autoimmune disorder leading to melanocyte destruction, causing depigmentation.
Langerhans Cells
- Immune cells found beneath the tight junction barrier.
- Extend dendritic processes during activation to capture external antigens.
- Present harmful antigens to initiate an immune response.
- Erythema Gyratum Repens is a paraneoplastic phenomenon with an accumulation of Langerhans cells in skin lesions, though responsible antigens remain unidentified.
Merkel Cells
- Mechanoreceptor cells located in the basal layer, associated with touch and fine spatial discrimination.
- Merkel Cell Carcinoma is a rare, aggressive skin cancer that appears as a painless, rapidly growing nodule, often in sun-exposed areas.
Dermis
- Provides structural support and nourishment to the skin.
- Collagen is the most abundant protein, with fibroblasts as the primary cell type.
- Contains macrophages and dermal dendritic cells.
- Houses hair follicles, sebaceous and sweat glands, blood vessels, lymphatic vessels, and nerves.
Papillary and Reticular Dermis
- Papillary dermis: the superficial layer made of loose connective tissue, highly vascularized, located just beneath the epidermis.
- Reticular dermis: deeper, denser connective tissue layer, comprising the bulk of the dermis.
- Kyrie disease is a perforating disorder resulting from connective tissue elimination associated with renal failure, hemodialysis, diabetes, and hepatic insufficiency.
- Anetoderma involves loss of elastic tissue, displaying sharply defined depressed papules and plaques, especially in the supraclavicular area.
Adnexal Structures
- Skin appendages include hair follicles (pilosebaceous units), sebaceous, sweat glands, and nails.
- Hair primarily influences social interactions, with an estimated total of around 5 million hair follicles, predominantly vellus.
- The scalp contains about 100,000 hair follicles, each undergoing 10–20 cycles in a lifetime.
- Hair growth rates are not affected by cutting/shaving; estrogens reduce growth rates while androgens enhance growth rates and hair diameter.
Hair Structure and Cycle
- Hair consists of three main parts: the cuticle (outer layer, maintains integrity), cortex (contains bulk keratins and keratin-associated proteins), and medulla (central core with loosely connected trichocytes and air spaces).
- The hair cycle comprises:
- Anagen: growth phase.
- Catagen: regression phase.
- Telogen: resting phase.
- Exogen: shedding phase.
Hair Growth Stages
-
Lanugo:
- Fine, soft hair covering the fetal body, typically shed in utero or shortly after birth.
- Duration of anagen phase lasts 1-3 months.
- Diameter is approximately 40 μm, length ranges from 1-2 cm.
-
Vellus:
- Very short, non-pigmented hair, often lacking medullary cells and arrector pili muscles.
- Contains tiny follicles with underdeveloped sebaceous glands, especially on the face.
- Anagen phase is shorter, lasting 1-2 weeks.
- Diameter measures about 60 μm, with length varying between 10-100 cm.
Hair Loss Conditions
-
Telogen Effluvium:
- Characterized by widespread and excessive shedding of hairs in the telogen phase.
-
Alopecia Areata:
- An autoimmune disorder leading to isolated patches of hair loss.
-
Androgenetic Alopecia:
- Genetic condition causing progressive thinning and eventual loss of hair, often referred to as male or female pattern baldness.
Sebaceous Glands
- Commonly located in areas like the face, behind the ears, and on the upper chest and back, mirroring the distribution pattern of acne vulgaris.
- Typically associated with hair follicles, except in specific regions:
- Vermilion Lips and Oral Mucosa: Fordyce spots or granules found here.
- Eyelids: Contain specialized glands known as meibomian glands.
- Areolae: Montgomery tubercles present in this region.
- Labia Minora and Prepuce: Known for their Tyson glands.
Acne Vulgaris
- Result of blockage or inflammation in the pilosebaceous unit affecting skin health.
Rosacea
- Chronic skin condition characterized by persistent facial redness and rashes.
- Commonly impacts the nose and cheeks, leading to visible blood vessels.
Sweat Glands
- Human body contains 2 to 4 million sweat glands capable of producing up to 10 liters of sweat per day.
- Hypothalamus plays a critical role in regulating body temperature and triggering sweating as a response.
Eccrine Glands
- Approximately 1.5 to 4 million eccrine glands located across skin surfaces, excluding specific areas such as the external auditory canals and vermilion lips.
- Highest concentration found in palms and soles of the feet.
- Under extreme conditions, can produce up to 3 liters of sweat in one hour.
- Innervated by postganglionic sympathetic fibers, releasing acetylcholine as the main neurotransmitter. Botulinum toxin can inhibit sweating by blocking acetylcholine release.
- Secretory structure includes a proximal coiled component located in the lower dermis, draining through a duct to an acrosyringium that opens on the skin surface.
- Eccrine sweat is a sterile, dilute electrolyte solution primarily composed of sodium chloride (NaCl), potassium, and bicarbonate, with composition influenced by emotional and environmental factors.
- Eccrine secretion may assist in delivering medications through the skin's outer layer and explains some side effects from certain chemotherapeutic agents.
- Common disorders related to sweat glands include hypo- and hyperhidrosis.
Miliaria Rubra
- Recognized as the most prevalent form of heat rash, manifesting mainly in warm, humid conditions, affecting sweat gland function.
Apocrine Glands
- Located in specific areas: axillae, anogenital region, periumbilical area, areolae, nipples, and the vermilion border of the lip.
- Larger than eccrine glands, with a structure comprising a secretory portion in the deep dermis and subcutaneous fat, and a duct that opens into the follicular canal.
- Secretion of apocrine glands increases due to catecholamines and cholinergic agonists, influenced by humoral mechanisms.
- Continuously releases small quantities of an oily, sterile, and odorless fluid with a viscosity and a pH of 5.0 to 6.5.
- Bacterial activity is essential for developing odor associated with apocrine sweat.
- Apocrine secretion is known as "decapitation" secretion, involving the "pinching off" of the luminal portion of secretory cells.
- Fox-Fordyce disease is a rare condition affecting these glands, characterized by severe itching in the underarm, pubic area, and around the nipples, leading to inflammation and enlargement.
Nails
- Serve various motor and sensory functions, aiding in social and sexual communication and providing aesthetic value.
- Protect distal phalanges from injury and enhance tactile discrimination and fine motor skills.
- The nail plate is semi-transparent, hard, slightly convex, and made of tightly packed cells called onychocytes.
- The cuticle, or eponychium, is a thin layer of keratinized epithelium that seals the nail edge, preventing contaminants.
- The lunula, a half-moon shape visible mainly on the thumb, marks the boundary between the nail matrix and nail bed.
- Nail folds surround the nail plate on three sides—one proximal and two lateral edges.
Vasculature Overview
- Divided into superficial, deep, and subcutaneous vascular plexuses.
- The superficial vascular plexus consists of paired arterioles and venules connected through capillary loops that penetrate the dermal papillae.
- Individual or combined vascular segments respond to internal and external stimuli, influencing skin disease.
Functions of Vasculature
- Supplies oxygen and nutrients to the skin.
- Maintains tissue homeostasis and normal skin function.
- Meets heightened nutritional demands during pathologic conditions.
- Acts as a barrier regulating the transfer of cells and molecules between blood and tissue.
- Regulates local blood flow, aiding thermoregulation and blood pressure management.
Disorders Associated with Skin Vasculature
-
Port-Wine Stains
- Characterized by a flat pink or red patch on newborns, evolving into a reddish-purplish mark.
- Result from dysfunctional endothelial cells leading to progressive dilation of immature venule-like structures.
-
Venous Ulcer
- Also known as venous stasis ulcer; painful condition.
- Arises from oxygen-poor blood pooling in veins, causing high-pressure buildup.
-
Hemangioma
- A benign tumor composed of extra blood vessels, appears as a rubbery lump or flat red patch.
Hypodermis/Subcutaneous Layer
- Located beneath the dermis, connecting skin to underlying muscles.
- Functions include insulation, energy storage, protection, immune surveillance, and hormone conversion.
- Contains lobules of fat cells (lipocytes) separated by collagenous fibrous septa and large blood vessels.
-
Panniculitis
- Inflammation of the panniculus; can be classified as septal or lobular and may occur with or without underlying vasculitis.
History of Present Illness
- Duration of symptoms can be categorized as acute, chronic, or exhibiting recurrences/remissions.
- Symptoms may present as constant, intermittent, exacerbated at night or in cold conditions.
- Evolution of lesions may be rapid or slow, with attention given to size and quantity changes.
- Identifying where skin lesions were first observed and how they've spread is crucial.
- Key symptoms to note include pruritus, pain, bleeding, lack of healing, changes in existing lesions, and any related systemic signs like fever.
- Severity is often ranked on a 10-point scale for evaluation.
- Factors influencing symptoms include sun exposure, temperature extremes, trauma, menstrual cycle, or pregnancy.
- Important to inquire about any previous illnesses, new medications, topical products, and environmental exposures.
- Record therapies attempted, including home remedies, and their effectiveness.
- Prior skin problems, diagnoses, biopsy results, and relevant studies are critical for history.
Medical History
- Include chronic illnesses that reflect on skin condition: diabetes, renal and hepatic diseases, HIV, polycystic ovarian syndrome, lupus, and thyroid issues.
- Surgical history should note any procedures, especially organ transplants.
- Assess immunosuppression origins: iatrogenic, infectious, or inherited causes.
- Document pregnancies and any history of psychiatric disorders.
- Consider past incidents of blistering sunburn, chemical exposure, or ionizing radiation exposure.
- Review medication history comprehensively: include prescriptions, nonprescription drugs, vitamins, and supplements, especially newly initiated treatments.
- Identify allergies to medications, foods, environmental antigens, and contact substances.
Social History
- Document occupation and its potential impact on skin health.
- Include hobbies and leisure activities that may involve skin exposure to irritants or allergens.
- Assess usage of alcohol, tobacco, and illicit drugs.
- Record sexual history, dietary habits, bathing routines, pets, and overall living conditions.
- History of travel or residence in areas endemic to infectious diseases may influence diagnosis.
- Note any cultural or religious practices that could impact health.
Family History
- Evaluate family history for atopy, which may indicate a predisposition to skin issues.
- Document any family history of cancer, autoimmune diseases, psoriasis, or skin discoloration conditions.
Review of Systems
- Perform a focused or comprehensive review based on the specific diagnosis being considered.
Physical Examination Overview
- A limited problem-focused exam may suffice for specific complaints but total body skin exams are warranted in several conditions.
- Indications for a full skin examination include personal or family history of skin cancer, risk factors such as sun exposure or immunocompromised status, generalized skin rashes, ill patients, and when diagnosis remains uncertain.
- Lesions' appearances may vary due to treatments or external factors like scratching and infection.
- Subjective symptoms, like pain from herpes zoster, can appear before visible vesicles.
- Side lighting enhances visibility of depth and lesion borders; palpation reveals characteristics like softness, firmness, tenderness, or fluid-filled nature.
Skin Assessment
- Color variations include jaundice, pallor, erythema, flushing, and cyanosis.
- Changes in temperature, excessive sweating, or oil production are significant.
- Assess skin elasticity and turgor to gauge hydration.
- Monitor for discoloration, pigment variations, and growths using the ABCDE method (Asymmetry, Border, Color, Diameter, Evolving).
- Examine rashes, noting primary and secondary lesions, their configuration, and distribution.
- Intertriginous areas should not be overlooked during examination.
Hair Examination
- Evaluate hair for density, texture, breakage, and any areas of alopecia or widening of follicular spaces.
- Look for scales, nits, and lice.
- Include assessments for eyebrows, axillary hair, and pubic hair as part of the exam.
Nail Assessment
- Observe nail color and check for plate and bed abnormalities.
Examination Reminders
- Ensure adequate lighting during the examination for accurate observation.
- Maintain patient comfort throughout the process.
- Always ask if a patient prefers a chaperone or assistant present during the examination.
- Photomicrographs are beneficial for monitoring treatment responses and require patient consent; ensure secure storage.
- Conduct a distant observation of the patient for general impressions, noting signs like cachexia, asymmetry, posture, and odor.
- Always take vital signs as part of the assessment.
HEENT Assessment
- Inspect face and neck for growths such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), actinic keratosis, or benign neoplasms.
- Evaluate for skin conditions like acne, warts, and skin tags.
- Assess sclera for icterus indicating potential liver issues related to xerosis.
- Check for hyperlinear dark eyelids, suggestive of atopic dermatitis.
- Look for crusts around the nasal area, which may indicate impetigo.
- Observe ear discharge during otoscopy, potentially pointing to seborrheic dermatitis.
- Examine tonsils for enlargement and congestion, which may lead to dermatitis or vasculitis.
- Note dry lips, particularly in patients undergoing Isotretinoin treatment.
Trunk Assessment
- Assess central upper chest for signs of sunburn or photoallergic contact dermatitis.
- Examine central chest for indications of seborrheic dermatitis.
- Investigate the inframammary area for intertrigo, warts, or fungal infections.
- Inspect the back, a common site for skin cancer.
- Auscultate breath sounds if an allergic reaction is suspected.
Heart Assessment
- Consider heart examination if there are nail complaints related to cardiac conditions or syndromes.
Abdomen Assessment
- Look for Cullen’s sign and Grey Turner’s sign as indicators of pancreatitis.
- Inspect the infraumbilical area for contact dermatitis or fungal infections.
Upper and Lower Extremities Assessment
- Evaluate extensor surfaces for psoriasis and flexural surfaces for atopic dermatitis.
- Examine wrists and interdigital spaces for signs of scabies.
- Inspect hands for various types of dermatitis.
- Check for swollen joints, commonly associated with psoriatic arthritis.
- Identify edema and ulcers, especially in diabetic patients or those with stasis dermatitis.
- Assess for signs of vasculitis and check for arterial pulses.
- Evaluate for Raynaud's phenomenon linked with systemic sclerosis.
Genital Examination
- Inspect genital area for growths (warts, molluscum contagiosum), discharges, or ulcerations indicative of sexually transmitted diseases.
Potassium Hydroxide (KOH) Preparation for Fungal Infections
- KOH preparation is used for scaling skin lesions with suspected fungal infections.
- Lesions are scraped with a no. 15 scalpel blade to collect scales on a glass microscope slide.
- The collected scales are treated with 1-2 drops of 10-20% KOH solution and covered with a cover slip.
- KOH dissolves keratin, facilitating the visualization of fungal elements under a microscope.
- This technique identifies:
- Hyphae in dermatophyte infections.
- Pseudohyphae and budding yeasts in Candida infections.
- "Spaghetti and meatballs" yeast forms in tinea versicolor.
Tzanck Smear for Herpesvirus Infections
- Tzanck smear is a cytologic technique primarily used for diagnosing herpesvirus infections, including HSV and VZV.
- An early vesicle is unroofed (not a pustule or crust) and the lesion base is gently scraped with a scalpel.
- Sample is placed on a glass slide, air-dried, and stained with Giemsa or Wright's stain.
- Presence of multinucleated epithelial giant cells indicates HSV or VZV infection.
- Additional tests such as culture, immunofluorescence microscopy, or genetic testing are necessary for specific virus identification.
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Test your knowledge on dermatology, including the structure and function of skin, diseases, and treatments. This quiz covers fascinating skin facts, basic anatomy, and key concepts in dermatology. Perfect for students and professionals alike!
