Laser Therapy Basics Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Laser Therapy Basics. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Laser Therapy Basics Indian Medical PG Question 1: What is the best range of UV light used for treatment of skin diseases?
- A. 100 – 200 nm
- B. > 700 nm
- C. 400 – 700 nm
- D. 200 – 400 nm (Correct Answer)
Laser Therapy Basics Explanation: ***200 – 400 nm***
- This range encompasses **UVA (320-400 nm)** and **UVB (290-320 nm)**, which are the most commonly used portions of the **UV spectrum** for treating various skin conditions like psoriasis and eczema.
- Specifically, **narrowband UVB (311-313 nm)** is highly effective due to its therapeutic benefits with reduced side effects compared to broadband UVB or UVA.
*100 – 200 nm*
- This range falls into the **vacuum UV (VUV)** spectrum, which is largely absorbed by air and is not practical for dermatological phototherapy due to its limited penetration and potential for significant cellular damage.
- It is known for its germicidal properties but is not used for treating skin diseases in living tissue due to its **high energy** and **low penetration** depth.
*> 700 nm*
- Wavelengths above 700 nm fall into the **infrared (IR) spectrum** or visible light, which primarily produces heat and has different therapeutic applications.
- While IR light can be used for therapies like **pain relief** and **wound healing**, it does not have the immunomodulatory effects on skin cells needed for conditions traditionally treated by UV.
*400 – 700 nm*
- This range represents the **visible light spectrum**, which is used in some dermatological treatments like **photodynamic therapy (PDT)** or for certain **pigmentary disorders**.
- However, visible light does not possess the same **immunomodulatory** and **antiproliferative effects** on keratinocytes and T-cells that make UV light effective for conditions like psoriasis.
Laser Therapy Basics Indian Medical PG Question 2: Which of the following burn cases requires IMMEDIATE referral to a specialized burn center?
- A. 25% superficial burn in adult
- B. Burn in palm
- C. 10% superficial burn in child
- D. 25% deep burn in adult (Correct Answer)
- E. 5% superficial scald in adult
Laser Therapy Basics Explanation: ***25% deep burn in adult***
- A **deep burn** (full thickness or deep partial thickness) covering **greater than 10% TBSA** is an **absolute criterion** for immediate referral to a specialized burn center per ABA guidelines.
- This is due to the high risk of **complications**, need for specialized **wound care**, and potential for **surgical intervention** like skin grafting.
- The **combination of depth and extent** makes this the most urgent scenario requiring immediate specialized care.
*25% superficial burn in adult*
- **Superficial burns** (first-degree) involve only the epidermis and typically heal within days without scarring.
- While 25% TBSA is extensive, **superficial burns** can often be managed with supportive care and do not meet the depth criterion for mandatory burn center referral.
*Burn in palm*
- **Burns involving hands** are considered **special areas** and typically require burn center evaluation for optimal functional outcomes.
- However, without specification of **depth and extent**, a small superficial palm burn may be managed locally initially, whereas the question asks for IMMEDIATE referral.
- The **25% deep burn** takes precedence due to its life-threatening nature and clear-cut indication.
*10% superficial burn in child*
- For children, burns greater than **10% TBSA** warrant consideration for burn center referral due to higher morbidity risk.
- However, **superficial burns** (first-degree) in children, while concerning, are less urgent than deep burns of significant extent.
- The depth of injury is a critical factor; superficial burns may be managed with close monitoring if appropriate expertise is available locally.
*5% superficial scald in adult*
- A **5% TBSA superficial burn** in an adult does not meet the threshold for mandatory burn center referral (typically >10% for partial thickness burns).
- **Superficial scalds** can usually be managed with outpatient care, wound dressing, and pain control.
- This would only require referral if other complicating factors were present (e.g., involvement of special areas, inhalation injury).
Laser Therapy Basics Indian Medical PG Question 3: Which of the following events does NOT occur in rods in response to light
- A. Opening of Na+ channels (Correct Answer)
- B. Activation of transducin
- C. Structural changes in rhodopsin
- D. Decreased intracellular cGMP
Laser Therapy Basics Explanation: ***Opening of Na+ channels***
- In response to light, **rods hyperpolarize** due to the **closure of Na+ channels**, which reduces the influx of positive ions.
- The opening of Na+ channels would lead to depolarization, which is the opposite of what occurs during light detection in rods.
*Activation of transducin*
- Light causes **conformational changes in rhodopsin**, which in turn activates the G-protein **transducin**.
- Activated transducin then goes on to activate **phosphodiesterase (PDE)** as part of the phototransduction cascade.
*Structural changes in rhodopsin*
- When light strikes the rhodopsin molecule, the **11-cis-retinal chromophore** isomerizes to **all-trans-retinal**.
- This **conformational change** in rhodopsin is the initial step that triggers the entire phototransduction pathway.
*Decreased intracellular cGMP*
- Activated **phosphodiesterase (PDE)**, stimulated by transducin, hydrolyzes **cGMP to GMP**.
- The reduction in **cGMP levels** leads to the closure of cGMP-gated Na+ channels, causing hyperpolarization.
Laser Therapy Basics Indian Medical PG Question 4: The most specific test to detect blood stains is:
- A. Benzidine test
- B. Teichmann's test
- C. Spectroscopic test (Correct Answer)
- D. Orthotoluidine test
Laser Therapy Basics Explanation: ***Spectroscopic test***
- The **spectroscopic test** is considered the most specific for detecting blood stains because it identifies the characteristic absorption bands of **hemoglobin** and its derivatives.
- This test is highly definitive due to the unique **light absorption properties** of blood components, making it less prone to false positives compared to chemical tests.
*Benzidine test*
- The **benzidine test** is a sensitive preliminary test for blood but is **not specific**, as it reacts with other oxidizing agents (e.g., rust, certain plant peroxidases).
- It works by detecting the **peroxidase-like activity of hemoglobin**, leading to color changes but lacks confirmation of blood origin.
*Teichmann's test*
- **Teichmann's test** (hemin crystal test) is a moderately specific confirmatory test that produces **rhombic crystals of hemin** when heated with glacial acetic acid and a halide salt.
- While more specific than presumptive tests, it can sometimes produce **false-negative results** with old or degraded bloodstains and may be less sensitive than spectroscopy.
*Orthotoluidine test*
- Similar to the benzidine test, the **orthotoluidine test** is another **presumptive test** that detects the peroxidase-like activity of hemoglobin, resulting in a blue-green color change.
- It is **highly sensitive but not specific**, meaning it can also give positive reactions with other substances that have similar peroxidase activity, leading to potential false positives.
Laser Therapy Basics Indian Medical PG Question 5: Which of the following are correct for managing hypertrophic scars?
1. Silicone gel sheeting
2. Intralesional steroid injections
3. Vitamin A gel applications
4. Laser treatment Select the answer using the code given below.
- A. 1, 3 and 4
- B. 1, 2 and 3
- C. 1, 2 and 4 (Correct Answer)
- D. 2, 3 and 4
Laser Therapy Basics Explanation: ***1, 2 and 4***
- **Silicone gel sheeting**, **intralesional steroid injections**, and **laser treatment** are all established and effective methods for managing hypertrophic scars.
- Silicone gel helps to hydrate the scar, reduce collagen synthesis, and decrease itching, while steroids reduce inflammation and collagen production, and lasers can help to improve scar texture and color.
*1, 3 and 4*
- This option incorrectly includes **Vitamin A gel applications** as a primary treatment. While retinoids can have some skin benefits, they are not a first-line or well-established treatment for hypertrophic scars.
- **Silicone gel sheeting** and **laser treatment** are indeed effective, but the inclusion of Vitamin A makes this option less accurate.
*1, 2 and 3*
- This option also incorrectly includes **Vitamin A gel applications**. While **silicone gel sheeting** and **intralesional steroid injections** are effective, Vitamin A is not a standard treatment for hypertrophic scars.
- The primary methods for managing hypertrophic scars focus on reducing collagen production and inflammation, which Vitamin A gel does not effectively address in this context.
*2, 3 and 4*
- This option correctly includes **intralesional steroid injections** and **laser treatment**, but it again incorrectly includes **Vitamin A gel applications** and omits **silicone gel sheeting**, which is a widely recommended and often first-line treatment.
- Omitting **silicone gel sheeting** significantly weakens the effectiveness of this combination as a comprehensive management strategy.
Laser Therapy Basics Indian Medical PG Question 6: What is the first-line treatment for melasma?
- A. Laser therapy
- B. Topical hydroquinone (Correct Answer)
- C. Chemical peels
- D. Microdermabrasion
Laser Therapy Basics Explanation: ***Topical hydroquinone***
- **Topical hydroquinone** (2-4%) is the **most effective single-agent treatment** among the given options, serving as the gold standard for melasma by inhibiting **tyrosinase enzyme** and melanin production.
- Demonstrates **highest efficacy rates** (60-80% improvement) when combined with strict sun protection, making it both first-line and most effective monotherapy choice.
*Laser therapy*
- Carries **high risk of paradoxical darkening** and post-inflammatory hyperpigmentation, especially in darker skin types common in melasma patients.
- Requires **specialized expertise** and should only be considered as adjunctive therapy after optimizing topical treatments, not as primary treatment.
*Chemical peels*
- Provide **variable and inconsistent results** as monotherapy, typically requiring multiple sessions with unpredictable outcomes.
- Risk of **post-inflammatory hyperpigmentation** particularly in Fitzpatrick skin types IV-VI, making them less reliable than hydroquinone.
*Microdermabrasion*
- Offers only **superficial exfoliation** with minimal clinical improvement in melasma pigmentation.
- May actually **worsen pigmentation** through mechanical irritation and is not recommended in evidence-based treatment guidelines.
Laser Therapy Basics Indian Medical PG Question 7: What is the best method to treat a large port-wine stain?
- A. Radiotherapy
- B. Excision with skin grafting
- C. Pulsed dye laser (Correct Answer)
- D. Tattooing
Laser Therapy Basics Explanation: ***Pulsed dye laser***
- The **pulsed dye laser (PDL)** is considered the **gold standard** for treating port-wine stains due to its specific targeting of hemoglobin in the dilated capillaries without damaging surrounding tissue.
- This treatment involves multiple sessions to progressively lighten the stain and prevent complications such as **nodularity** and **tissue hypertrophy**.
*Radiotherapy*
- **Radiotherapy** is generally not recommended for port-wine stains due to its potential for **scarring**, **pigment changes**, and risk of **malignancy**.
- It is an aggressive treatment typically reserved for **cancerous conditions** or severe proliferative vascular lesions not amenable to other treatments.
*Tattooing*
- **Tattooing** involves injecting skin-colored pigments into the lesion to camouflage it, but it does not treat the underlying vascular abnormality.
- This method can result in an **artificial appearance**, **uneven coverage**, and potential for **allergic reactions** or infections.
*Excision with skin grafting*
- **Surgical excision** of a large port-wine stain would result in a **significant scar** and require **skin grafting**, which carries risks of graft failure, poor aesthetic outcome, and color mismatch.
- This method is generally reserved for very small, localized lesions or those with significant **nodular hypertrophy** that cannot be effectively managed by laser therapy.
Laser Therapy Basics Indian Medical PG Question 8: Which of the following statements about conjunctival lesions is NOT true?
- A. Arise from any part of conjunctiva
- B. Can cause Astigmatism
- C. Surgery is treatment of choice (Correct Answer)
- D. UV exposure is risk factor
Laser Therapy Basics Explanation: ***Surgery is treatment of choice***
- While surgery can be used to treat conjunctival lesions, it is not always the **treatment of choice**, especially for smaller, asymptomatic lesions like **pinguecula** which may only require observation and lubrication.
- Many conjunctival lesions, such as uncomplicated **pterygium** or **pinguecula**, are managed conservatively unless they cause significant symptoms, vision impairment, or cosmetic concerns.
*Arise from any part of conjunctiva*
- **Conjunctival lesions** can indeed arise from various parts of the conjunctiva, including the palpebral, bulbar, and forniceal conjunctiva.
- For example, **pterygium** typically arises from the bulbar conjunctiva, while **pinguecula** also originates in the bulbar conjunctiva, specifically in the interpalpebral fissure.
*Can cause Astigmatism*
- Larger **conjunctival lesions**, particularly a **pterygium** that encroaches onto the cornea, can induce or alter astigmatism.
- The growth of the lesion can change the **curvature of the cornea**, leading to optical distortion and astigmatism.
*UV exposure is risk factor*
- **Ultraviolet (UV) light exposure** is a well-established risk factor for the development of many conjunctival lesions, including **pterygium** and **pinguecula**.
- Chronic UV exposure leads to **elastotic degeneration** of the conjunctival collagen and is thought to play a key role in the pathogenesis of these growths.
Laser Therapy Basics Indian Medical PG Question 9: A 40 year old man presented with a flat 1x1cm scaly, itchy black mole on the front of thigh. Examination did not reveal any inguinal lymphodenopathy. The best course of management would be:
- A. FNAC of lesion
- B. Incision biopsy
- C. Wide excision with inguinal lymphadenectomy
- D. Excision biopsy (Correct Answer)
Laser Therapy Basics Explanation: ***Excision biopsy***
- A **flat, scaly, itchy, black mole** is highly suspicious for **melanoma**, and an excision biopsy provides the most accurate histopathological diagnosis and depth assessment.
- This procedure removes the entire lesion with a narrow margin of normal-appearing skin, allowing for comprehensive evaluation of its nature and determining further management.
*FNAC of lesion*
- **Fine needle aspiration cytology (FNAC)** is generally used for evaluating palpable masses or lymph nodes, not primary skin lesions like a suspicious mole.
- It provides only cellular samples, making it difficult to assess architectural features, depth of invasion, or determine definitive malignancy in skin lesions.
*Incision biopsy*
- An **incision biopsy** involves removing only a partial sample of the lesion, which can lead to sampling error and an inaccurate diagnosis if the most aggressive part is missed.
- For suspected melanoma, an incomplete biopsy can compromise subsequent staging and definitive treatment planning.
*Wide excision with inguinal lymphadenectomy*
- This is an **overly aggressive initial approach** before a definitive diagnosis of melanoma and its stage has been established.
- **Wide excision** is typically performed after an excision biopsy confirms melanoma and determines its depth, while **lymphadenectomy** is indicated for confirmed lymph node involvement.
Laser Therapy Basics Indian Medical PG Question 10: Comment on the image shown:
- A. Corn
- B. Callosity (Correct Answer)
- C. Warts
- D. Cutaneous horn
Laser Therapy Basics Explanation: ***Callosity***
- The image displays several **thickened, hyperkeratotic patches** on the palm, characteristic of callosities.
- Callosities are caused by repeated friction and pressure, leading to **diffuse epidermal thickening** without a central core.
*Corn*
- A **corn** is a small, well-demarcated lesion with a **central core** that causes localized pain, unlike the diffuse thickening seen here.
- They typically occur over bony prominences and are less spread out than the lesions in the image.
*Warts*
- **Warts** are caused by the **human papillomavirus (HPV)** and present as rough, elevated lesions with characteristic **black puncta** (thrombosed capillaries) upon paring, which are not visible in the image.
- They often have a **papillomatous** or verrucous surface, different from the relatively smooth, thickened appearance here.
*Cutaneous horn*
- A **cutaneous horn** is a conical projection of **hyperkeratotic material** resembling an animal horn, typically developing on sun-exposed areas.
- It is usually a solitary lesion and has a different morphology than the multiple, flat, thickened lesions shown.
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