Photodynamic Therapy Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Photodynamic Therapy. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Photodynamic Therapy Indian Medical PG Question 1: Benzoyl peroxide acts in acne vulgaris by:
- A. Decreasing bacterial count (Correct Answer)
- B. Reduces sebum production
- C. Acts as a keratolytic agent
- D. Increases epithelial turnover
Photodynamic Therapy Explanation: ***Decreasing bacterial count***
- **Benzoyl peroxide** is a highly effective topical treatment for acne primarily due to its potent **antimicrobial activity** against *Cutibacterium acnes*, the bacterium implicated in acne pathogenesis.
- It works by releasing **free radicals** that disrupt bacterial cell membranes and metabolism, thereby reducing the bacterial load in follicles.
*Reduces sebum production*
- While sebaceous gland activity is critical in acne, benzoyl peroxide does **not directly reduce sebum production**; retinoids like isotretinoin are known for this effect.
- Its primary action is focused on combating bacteria and mildly promoting desquamation rather than affecting **lipid synthesis**.
*Acts as a keratolytic agent*
- Benzoyl peroxide does possess some **keratolytic activity**, aiding in the shedding of dead skin cells and preventing pore blockage.
- However, its keratolytic action is **less pronounced** compared to agents like salicylic acid or tretinoin, and it is not its primary mechanism of action.
*Increases epithelial turnover*
- While benzoyl peroxide does promote a mild increase in **epithelial cell turnover**, helping to clear clogged pores, it is not its main mechanism of action or defining characteristic.
- **Topical retinoids** (e.g., tretinoin, adapalene) are far more effective and primarily used to normalize follicular keratinization and increase cell turnover.
Photodynamic Therapy Indian Medical PG Question 2: Which drug is most likely to induce photosensitivity?
- A. Metronidazole
- B. Tetracycline (Correct Answer)
- C. Ivermectin
- D. Fluconazole
Photodynamic Therapy Explanation: ***Tetracycline***
- **Tetracyclines** are well-known to cause **photosensitivity reactions**, leading to exaggerated sunburns, rashes, or skin discoloration upon sun exposure.
- This adverse effect is thought to be due to an interaction between the drug and UV light, leading to the formation of reactive oxygen species and subsequent cell damage.
*Metronidazole*
- While metronidazole can cause a variety of side effects, significant **photosensitivity** is generally not considered a common or prominent adverse reaction.
- It is often associated with a **disulfiram-like reaction** when consumed with alcohol, as well as gastrointestinal upset and a metallic taste.
*Ivermectin*
- **Ivermectin** is primarily used as an antiparasitic agent and is not typically associated with **photosensitivity** as a common side effect.
- Its main adverse effects are usually related to the Mazzotti reaction during treatment of onchocerciasis or other systemic symptoms like dizziness or nausea.
*Fluconazole*
- **Fluconazole**, an antifungal medication, has a relatively low incidence of causing **photosensitivity** compared to other drug classes.
- Common side effects include gastrointestinal disturbances, headache, and elevated liver enzymes, but severe phototoxic reactions are rare.
Photodynamic Therapy Indian Medical PG Question 3: Enucleation is done for - a) Retinoblastoma b) Malignant melanoma c) Glaucoma d) Phthisis bulbi
- A. abd (Correct Answer)
- B. abc
- C. acd
- D. bcd
- E. ab
Photodynamic Therapy Explanation: ***abd***
- **Enucleation** (surgical removal of the entire eyeball) is indicated for **retinoblastoma** and **malignant melanoma** due to the malignant nature of these conditions and the risk of metastasis.
- It is also performed in cases of severe **phthisis bulbi**, where the eye is shrunken, non-functional, and often painful, to alleviate symptoms and for cosmetic reasons.
*abc*
- This option incorrectly includes **glaucoma** as a primary indication for enucleation.
- While severe, painful, and blind glaucomatous eyes might eventually undergo enucleation, it is not the initial or typical treatment; many other medical and surgical options are explored first.
*acd*
- This option incorrectly includes **glaucoma** for the aforementioned reasons and omits **malignant melanoma**.
- **Malignant melanoma** of the choroid is a significant indication for enucleation, especially in larger tumors, due to its metastatic potential.
*bcd*
- This option incorrectly includes **glaucoma** and omits **retinoblastoma**.
- **Retinoblastoma** is a life-threatening pediatric malignancy, and prompt enucleation is often crucial for treatment and survival.
Photodynamic Therapy Indian Medical PG Question 4: A patient presents with a skin rash that is exaggerated on sun exposure. What is the repair mechanism involved in this condition?
- A. Nucleotide excision repair (Correct Answer)
- B. Base excision repair
- C. Mismatch repair
- D. Double stranded DNA break repair
Photodynamic Therapy Explanation: ***Nucleotide excision repair***
- This mechanism is responsible for repairing **bulky lesions** in DNA, such as **pyrimidine dimers** caused by **UV radiation** from sun exposure.
- Patients with defects in nucleotide excision repair (e.g., **xeroderma pigmentosum**) are highly sensitive to sunlight and develop skin rashes, pigment changes, and skin cancers.
*Base excision repair*
- This pathway primarily corrects **small damaged bases** that do not cause significant distortion of the DNA helix, such as deaminated, oxidized, or alkylated bases.
- It does not primarily address the bulky lesions induced by UV light that cause exaggerated sun sensitivity.
*Mismatch repair*
- This system corrects errors, like **mismatched base pairs**, that are incorporated during DNA replication.
- It is not directly involved in repairing DNA damage caused by environmental factors like UV radiation.
*Double stranded DNA break repair*
- This mechanism repairs **double-strand breaks** in DNA, which are highly deleterious lesions caused by ionizing radiation or oxidative stress.
- While critical for genome stability, it is not the primary repair pathway for UV-induced DNA lesions or the direct cause of sun sensitivity.
Photodynamic Therapy Indian Medical PG Question 5: Bright light therapy is used for?
- A. Adjustment disorder
- B. Anxiety
- C. Schizophrenia
- D. Seasonal affective disorder (Correct Answer)
Photodynamic Therapy Explanation: ***Seasonal affective disorder***
- **Bright light therapy** is a primary treatment for **seasonal affective disorder (SAD)**, particularly **winter depression**, by simulating natural outdoor light.
- Exposure to bright light can help regulate the body's **circadian rhythm** and neurotransmitter levels, which are often disrupted in SAD.
*Adjustment disorder*
- This disorder is a **stress-related condition** where a person has difficulty coping with a specific stressor or event.
- Treatment typically involves **psychotherapy** and addresses the specific stressor, not light therapy.
*Anxiety*
- **Anxiety disorders** are characterized by excessive worry, fear, or apprehension.
- Treatment usually involves **cognitive behavioral therapy (CBT)**, medications (e.g., SSRIs), or a combination thereof, not bright light therapy.
*Schizophrenia*
- **Schizophrenia** is a chronic and severe mental disorder affecting how a person thinks, feels, and behaves, involving psychosis.
- Management primarily relies on **antipsychotic medications** and psychosocial interventions, with no established role for bright light therapy.
Photodynamic Therapy 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
Photodynamic Therapy 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.
Photodynamic Therapy Indian Medical PG Question 7: 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
Photodynamic Therapy 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.
Photodynamic Therapy Indian Medical PG Question 8: Dermatological manifestation of which of the following diseases?
- A. Photo dermatitis
- B. Pellagra (Correct Answer)
- C. Acrodermatitis enteropathica
- D. Vitamin B deficiency
Photodynamic Therapy Explanation: ***Pellagra***
- The image shows a classic "butterfly" rash on the face, specifically a photosensitive dermatitis, which is a hallmark of **pellagra**.
- Pellagra is caused by a deficiency of **niacin (vitamin B3)**, characterized by the "3 D's": **dermatitis**, **diarrhea**, and **dementia**.
*Photo dermatitis*
- While pellagra often presents with photosensitive dermatitis, "photo dermatitis" is a general term for **skin inflammation caused by light exposure** and not a specific disease itself.
- It could be caused by various factors, including medication, immune reactions, or other underlying conditions, but the pattern seen here is highly suggestive of pellagra.
*Acrodermatitis enteropathica*
- This condition is a **hereditary zinc deficiency** that typically presents with a periorificial and acral dermatitis.
- The skin lesions are typically **vesicular-pustular or eczematous** and do not usually have the distinct butterfly pattern of photosensitive dermatitis seen in the image.
*Vitamin B deficiency*
- While pellagra is a vitamin B **(niacin, B3)** deficiency, this option is too broad.
- Other vitamin B deficiencies, such as **riboflavin (B2)** or **pyridoxine (B6)** deficiency, have different dermatological manifestations like angular cheilitis, glossitis, or seborrheic dermatitis, but not the characteristic facial rash seen here.
Photodynamic Therapy Indian Medical PG Question 9: An 8-year-old girl has extreme photosensitivity since birth. She has recently been diagnosed with skin cancer. What is the diagnosis?
- A. Xeroderma Pigmentosum (Correct Answer)
- B. Bloom syndrome
- C. Griscelli syndrome
- D. Chediak Higashi syndrome
Photodynamic Therapy Explanation: ***Xeroderma Pigmentosum***
- This condition is characterized by an extreme sensitivity to **ultraviolet (UV) light** from birth due to defects in **DNA repair mechanisms**, leading to severe sunburns, pigmentary changes (freckles, hypopigmented macules), and a high risk of developing **skin cancers** at a young age.
- The history of extreme photosensitivity since birth and the diagnosis of skin cancer in an 8-year-old girl is highly indicative of Xeroderma Pigmentosum.
*Bloom syndrome*
- Bloom syndrome is an inherited disorder characterized by **stunted growth**, a **photosensitive facial rash (telangiectatic erythema)**, and a predisposition to **various cancers**, including leukemia and lymphomas.
- While photosensitivity and cancer risk are present, the extreme skin damage and early onset of specific skin cancers (as opposed to leukemias/lymphomas often seen in Bloom) make Xeroderma Pigmentosum a more fitting diagnosis.
*Griscelli syndrome*
- Griscelli syndrome is a rare autosomal recessive disorder characterized by **partial albinism**, immunodeficiency, and neurological impairment.
- While it involves pigmentary abnormalities, it does not typically present with the extreme photosensitivity or the very early skin cancer development described in the patient.
*Chediak Higashi syndrome*
- Chediak-Higashi syndrome is an autosomal recessive disorder characterized by **partial albinism**, recurrent pyogenic infections, and neurological abnormalities, due to defective lysosomal trafficking.
- This syndrome is not primarily associated with extreme photosensitivity leading to early skin cancers but rather with immunodeficiency and neurological issues.
Photodynamic Therapy Indian Medical PG Question 10: A 6-year-old child born to consanguinity has pallor and intolerance to sunlight. His urine was exposed to Wood's light. Probable diagnosis is:
- A. SLE
- B. Xeroderma pigmentosum
- C. Gunther disease (Correct Answer)
- D. Bloom syndrome
Photodynamic Therapy Explanation: ***Gunther disease***
- The combination of **pallor**, **intolerance to sunlight** (photosensitivity), **consanguinity**, and particularly the **red fluorescence of urine under Wood's light** (due to increased uroporphyrins and coproporphyrins) is highly characteristic of **congenital erythropoietic porphyria (CEP)**, also known as Gunther disease.
- This is an **autosomal recessive** disorder of heme synthesis, leading to accumulation of porphyrin precursors. Affected individuals often have **erythrodontia** (reddish-brown discoloration of teeth), severe **anemia**, and **hemolysis**, alongside marked photosensitivity.
*SLE*
- **Systemic lupus erythematosus (SLE)** can cause **photosensitivity** and **pallor (due to anemia)**, but it is an autoimmune disease, not an inborn error of metabolism.
- It does not typically present with red fluorescent urine under Wood's light, which is a specific finding for porphyrias.
*Xeroderma pigmentosum*
- This is a rare **autosomal recessive** genetic disorder characterized by extreme **photosensitivity** and a high risk of skin cancers due to a defect in DNA repair mechanisms.
- While it causes severe photosensitivity, it does not involve abnormalities in porphyrin metabolism or lead to red fluorescent urine.
*Bloom syndrome*
- **Bloom syndrome** is a rare **autosomal recessive** genetic disorder characterized by **photosensitivity**, **short stature**, a **distinctive facial appearance**, and an increased risk of cancer.
- It does not involve porphyrin metabolism or result in red fluorescent urine under Wood's light.
More Photodynamic Therapy Indian Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
A