Understanding Keloids and Mechanical Trauma

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary feature that characterizes all types of acanthosis nigricans?

Presence of diabetes

Development at older age

Increased growth factor receptor signaling in the skin (correct)

Thickened, hyperpigmented skin

In what percentage of cases is acanthosis nigricans associated with benign conditions?

70%

50%

60%

80% (correct)

Which of the following conditions is most commonly associated with acanthosis nigricans?

Rheumatoid arthritis

Age-related macular degeneration

Cystic fibrosis

Gastrointestinal adenocarcinoma (correct)

Which receptor tyrosine kinase is believed to stimulate the increased signaling leading to acanthosis nigricans in type 2 diabetes?

IGFR1 Signup and view all the answers

During which life stages is acanthosis nigricans most commonly seen?

Childhood or puberty Signup and view all the answers

What characterizes junctional nevi?

They are early lesions that are flat, symmetric, and uniform. Signup and view all the answers

What is a common feature of dysplastic nevi?

They exhibit coalescent intraepidermal nests. Signup and view all the answers

What genetic mutations are often associated with the development of dysplastic nevi?

Loss-of-function mutations in CDKN2A. Signup and view all the answers

Which of the following statements about melanoma is true?

It can be cured if detected and treated early. Signup and view all the answers

Which characteristic best describes dysplastic nevi?

They are often larger than 5 mm and may have irregular features. Signup and view all the answers

What is the relationship between UV radiation and melanoma?

Exposure to UV radiation is linked to acquired mutations that increase melanoma risk. Signup and view all the answers

What are the potential clinical implications of dysplastic nevi?

They can serve as markers for an increased risk of melanoma. Signup and view all the answers

Which of the following best describes compound nevi?

They form when junctional nevi grow into the underlying dermis. Signup and view all the answers

What characterizes a keloid scar?

It grows beyond the original wound boundaries. Signup and view all the answers

Which factor is NOT related to the severity of a thermal injury?

Shape of the colliding object Signup and view all the answers

What is a characteristic feature of full-thickness burns?

Dry, white or charred, and painless. Signup and view all the answers

What occurs during burn shock?

Capillary leak that persists for 24 hours. Signup and view all the answers

Which type of mechanical trauma includes lacerations?

Patterns of injury classifications. Signup and view all the answers

What is a consequence of the fluid loss associated with burn injuries?

Increased internal pressure due to fluid accumulation. Signup and view all the answers

Which type of burn affects the dermis and is characterized by pain?

Partial-thickness burns (2nd degree) Signup and view all the answers

Among the following, which is considered the greatest threat to life in burn patients?

Sepsis Signup and view all the answers

What is the primary cause of epidermal injury in aureus infections?

Bacterial production of a toxin that cleaves desmoglein 1 Signup and view all the answers

Which clinical manifestation is commonly associated with infections of Trichophyton rubrum?

Erythematous plaques with elevated scaling borders Signup and view all the answers

What is a common predisposing factor for Tinea cruris infection?

Maceration due to heat and friction Signup and view all the answers

Which type of tinea is characterized by asymptomatic, patchy skin lesions often associated with hair loss?

Tinea capitis Signup and view all the answers

How common is Tinea pedis among the general population?

30% to 40% Signup and view all the answers

In Tinea pedis, what is primarily responsible for the inflammatory response?

Bacterial superinfection Signup and view all the answers

What are the presenting symptoms of Tinea faciei?

Patchy lesions with mild erythema Signup and view all the answers

What is the significance of desmoglein 1 in the epidermis?

It plays a role in cell-to-cell adhesion Signup and view all the answers

Which of the following is a characteristic feature of dermatofibrosarcoma protuberans?

Translocation involving the genes COL1A1 and PDGFB Signup and view all the answers

What is the typical size of dermatofibrosarcoma protuberans lesions?

Usually between 1 cm and several cm Signup and view all the answers

What sign is characterized by localized dermal edema and wheal formation when lesional skin is rubbed?

Darier sign Signup and view all the answers

In which age group is urticaria most commonly observed?

20-40 years Signup and view all the answers

What is the primary cause of urticaria?

Histamine release from mast cells Signup and view all the answers

Which of the following is a systemic symptom related to mastocytosis?

Gastrointestinal bleeding Signup and view all the answers

What is the appearance of cutaneous lesions in mastocytosis?

Multiple lesions often grouped together Signup and view all the answers

What happens to urticarial lesions over time?

Lesions develop and fade within hours Signup and view all the answers

What is the main type of cell involved in mast cell disease?

Mast cells Signup and view all the answers

What is a key feature of acute inflammatory dermatoses, specifically urticaria?

Formation of wheals Signup and view all the answers

What characterizes delayed primary closure in wound management?

Incision is left open to treat infection before closure. Signup and view all the answers

What type of ulcer primarily results from chronic venous hypertension?

Venous leg ulcers Signup and view all the answers

Which type of ulcer is especially painful and results from peripheral artery atherosclerosis?

Arterial ulcers Signup and view all the answers

What defines primary closure in wound healing?

Edges of incision are closely opposed to heal by intention. Signup and view all the answers

What is a characteristic feature of hypertrophic scars?

They typically regress over a few months. Signup and view all the answers

What is a significant environmental factor linked to sporadic melanoma cases?

UV radiation exposure Signup and view all the answers

Which of the following is NOT one of the ABCDE warning signs of melanoma?

Color consistency Signup and view all the answers

What type of growth phase do melanoma tumors typically undergo as they progress?

Superficial spreading phase followed by vertical growth phase Signup and view all the answers

Which of the following accurately describes the borders of melanoma?

Irregular and often notched Signup and view all the answers

Which genetic mutation is most frequently associated with melanoma?

Mutations disrupting cell cycle control Signup and view all the answers

What is the primary characteristic of the lesions associated with psoriasis?

Well-demarcated, pink to salmon-colored plaques with silver-white scales Signup and view all the answers

Which areas of the body are most commonly affected by psoriasis?

Elbows, knees, scalp, and lower back Signup and view all the answers

What role do CD4+ T-cells play in psoriasis?

They lead to the overproduction of multiple cytokines. Signup and view all the answers

What is the significance of the Auspitz sign in psoriasis?

Reveals the proximity of dermal papillae to the overlying scale. Signup and view all the answers

What is a consequence of psoriasis that involves nail changes?

Total body erythema and scaling Signup and view all the answers

What is the primary risk factor that can hasten the lowering of body temperature?

High humidity and wet clothing Signup and view all the answers

At what body temperature does loss of consciousness typically occur?

90F Signup and view all the answers

What type of hyperpigmentation is typical of freckles?

Increased amounts of melanin pigment within basal keratinocytes Signup and view all the answers

How do lentigines differ from freckles with respect to sunlight exposure?

Lentigines do not change at all with sunlight exposure Signup and view all the answers

What is a common feature of melanocytic nevi?

Caused by acquired mutations in RAS signaling pathway Signup and view all the answers

Which of the following statements is true about freckles?

They fade and darken in a cyclic fashion Signup and view all the answers

What histologic feature characterizes lentigines?

Linear nonnested melanocytic hyperplasia Signup and view all the answers

Which of the following describes the primary mechanism of injury induced by hypothermia?

Physical disruptions within cells due to high salt concentrations Signup and view all the answers

What is the primary cause of neonatal herpes infection?

Exposure during passage through the birth canal Signup and view all the answers

Which form of keratitis is associated with herpes simplex virus (HSV)?

Herpes epithelial keratitis Signup and view all the answers

How does Varicella-Zoster Virus (VZV) primarily spread?

Respiratory aerosols Signup and view all the answers

What is a common symptom of exanthem subitum caused by HHV-6 and HHV-7?

Rapid rise in temperature Signup and view all the answers

What risk factor increases the severity of VZV infections in individuals?

Immunocompromised status Signup and view all the answers

What type of rash is typically associated with chickenpox caused by VZV?

Maculopapular rash Signup and view all the answers

In what part of the body is latent Varicella-Zoster Virus most likely to be found?

Dorsal root ganglia Signup and view all the answers

Which statement about genital herpes is true?

It can present without vesicles. Signup and view all the answers

Study Notes

Keloids

Keloids are scar tissues that extend beyond the original wound area and do not regress.
Formation is influenced by individual predisposition and is more prevalent in black populations.

Mechanical Trauma

Traumatic injuries are caused by the shape and energy of the object impacting the tissue.
Injury patterns include abrasions, contusions, lacerations, incised wounds, and puncture wounds.

Thermal Injury

Severity of thermal injuries is determined by burn depth, body surface percentage affected, and inhalation of toxic fumes.
1st Degree Burns: Affect only the epidermis; redness and pain are common.
2nd Degree Burns: Involve the dermis, presenting with blisters and pain.
3rd Degree Burns: Extend to subcutaneous tissues; skin appears white, charred, dry, and painless.
Burn shock occurs due to capillary leaks, fluid loss, and interstitial edema; severity dictates the rate and volume of fluid loss.
Parkland formula is used for burn injury fluid resuscitation.

Dysplastic Nevi

Dysplastic nevi can be precursors to melanoma, especially when numerous.
Mutations in the NRAS and BRAF genes increase malignant transformation risks.
Larger than typical nevi, can appear irregular or "pebbly," and show cytologic atypia.
Clinical significance includes the potential for melanoma development.

Melanoma

Melanoma is the most aggressive skin cancer but is highly treatable if detected early.
Commonly arises in sun-exposed areas but can also originate from mucosal surfaces.
Inherited susceptibility may account for 10-15% of cases, showcasing an autosomal dominant inheritance with variable penetrance.
Strongly linked to UV radiation exposure.

Acanthosis Nigricans

Characterized by thick, hyperpigmented skin resembling velvet, often in skin folds.
Primarily associated with benign conditions; may occasionally indicate malignancies.
Often seen in children or adolescents, can arise from obesity, endocrine disorders, or as part of congenital syndromes.
Familial forms are linked to FGFR3 mutations and increased IGFR1 signaling.
In middle-aged individuals, it may indicate gastrointestinal adenocarcinoma.

Dermatofibrosarcoma Protuberans

A slow-growing primary fibrosarcoma of the skin; locally aggressive but rarely metastatic.
Hallmarked by a translocation of COL1A1 and PDGFB genes.
Often presents as a firm nodule on the trunk and may ulcerate.

Mastocytosis

Involves increased mast cell numbers, primarily affecting children with urticaria pigmentosa being the most common form.
Systemic forms can cause complications, including pruritus, flushing, and gastrointestinal symptoms.
Characterized by Darier sign and dermatographism, responses triggered by localized skin stimuli.

Acute Inflammatory Dermatoses: Urticaria

Urticaria, or hives, occurs due to localized mast cell degranulation, leading to edematous wheals.
Episodes typically last under 24 hours and can reoccur.
Often result from antigen-induced mast cell mediator release and can affect any skin area exposed to pressure.

Superficial Fungal Infections

Caused by Trichophyton Rubrum with distinct types based on infection location:
- Tinea Capitis: Scalp infection, common in children, leads to scaling and hair loss.
- Tinea Corporis: Affects skin trunk; often appears as round, itchy plaques.
- Tinea Cruris: Groin infection prevalent among obese men in warm weather.
- Tinea Pedis (Athlete's Foot): Affects 30-40% of the population, often caused by superinfected bacterial reactions.
Onychomycosis: Refers to nail infections arising from tinea, causing nail plate changes.

Tissue Healing and Ulcer Types

TCG-β is a strong fibrogenic agent, impacting ECM deposition through a balance of fibrogenic agents, metalloproteinases (MMPs), and TIMPs.
Primary closure involves closely opposing incision edges using sutures or staples for healing by primary intention.
Secondary closure leaves the incision open, allowing healing through new tissue formation from the wound's base and sides, resulting in scarring.
Delayed primary closure permits an open incision for several days to address infection and tissue viability before closure with sutures or grafts.
Venous leg ulcers commonly affect the elderly, caused by chronic venous hypertension, leading to poor oxygen delivery and poor healing.
Arterial ulcers are linked to atherosclerosis and diabetes, resulting in ischemia, painful necrotic lesions.
Diabetic ulcers primarily affect the feet due to vascular disease, neuropathy, and infections, leading to extensive granulation tissue.
Pressure sores result from prolonged tissue compression against bone, causing ulceration and necrosis.
Hypertrophic scars result from excessive collagen deposition, characterized by rapid growth and eventual regression.

Hypothermia

Body temperature at 90°F can cause loss of consciousness, bradycardia, and atrial fibrillation as core temperature drops.
Hypothermia injuries arise from direct physical disruption in cells due to salt crystallization and indirect circulatory changes, leading to edema and hypoxia.

Disorders of Pigmentation and Melanocytes

Freckles are small (1mm- several mm), tan-red or light brown macules that hyperpigment with sun exposure, characterized by no increase in melanocyte number but in melanin levels.
Lentigo represents benign melanocyte hyperplasia, commonly seen in infants, presenting as oval, tan-brown macules, without darkening in sunlight.
Melanocytic nevi are benign neoplasms often caused by mutations in the RAS signaling pathway, with variations in color and irregular borders being concerning features for melanoma.
ABCDEs of melanoma serve as warning signs: Asymmetry, Borders (irregular), Color (variegated), Diameter (≥6 mm), and Evolution or change over time.

Psoriasis

Chronic inflammatory autoimmune disorder driven by environmental and genetic factors, particularly HLA gene variants.
Affects areas like elbows, knees, and scalp, characterized by well-demarcated, pink plaques with silver-white scales.
Auspitz sign reflects bleeding points when the scaling is removed due to proximity of vessels in the dermal papillae.
Associated with total body erythema (erythroderma) and specific nail changes affecting about 30% of patients.

Seborrheic Dermatitis

An inflammation of the epidermis without a clearly defined cause, not exclusively linked to sebaceous glands.

Genital Herpes

Caused primarily by HSV-2, presenting with vesicular lesions on genital mucous membranes, often turning into ulcers.
Transmission to neonates during birth can lead to severe infection with generalized symptoms.
Symptoms can include lymphadenopathy, splenomegaly, and necrotic foci in vital organs.

Varicella-Zoster Virus (VZV) Infections

VZV causes chickenpox in acute infections and shingles upon reactivation.
Notable for mild symptoms in children but severe cases in adults and immunocompromised individuals.
VZV evades immunity to establish latent infections in sensory ganglia and spreads through respiratory droplets and hematogenous routes.
Chickenpox rash appears about two weeks post-respiratory infection, presenting with widespread vesicular lesions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the concepts of keloid formation and mechanical trauma. It covers the characteristics of keloids, including their tendency not to regress and their prevalence in specific populations. Additionally, it delves into the nature of mechanical injuries, highlighting how they vary based on the shape of the colliding object and the energy involved.