Phototherapy Protocols — MCQs
PUVA therapy is used in all except:
How does narrowband UVB therapy work in psoriasis?
All of the following are used in systemic therapy of psoriasis except
Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?
Podophyllum resin is indicated in the treatment of:
Laser used in LASIK is:
What is the best time to give oral psoralen with UVA -
The laser procedure, most often used for treating iris neovascularization is
A 45-day-old infant presents with seizures. Examination reveals he is icteric, has bulging fontanelles, and exhibits opisthotonic posture. Which of the following treatments is NOT indicated?
In a term baby who is 72 hours old, breastfeeding well, and has a bilirubin level of 14 mg/dL, which of the following statements is true?
Phototherapy Protocols Indian Medical PG Practice Questions and MCQs
Question 1: PUVA therapy is used in all except:
- A. Psoriasis
- B. Vitiligo
- C. Mycosis fungoides
- D. Melasma (Correct Answer)
Explanation: ***Melasma*** - **PUVA (Psoralen plus UVA) therapy** is contraindicated in melasma due to its potential to worsen hyperpigmentation and cause paradoxical darkening. - Melasma is best managed with topical agents like **hydroquinone**, **tretinoin**, and chemical peels, along with strict **sun protection**. *Psoriasis* - **PUVA therapy** is a well-established and effective treatment for moderate to severe psoriasis, especially for patients with widespread plaques. - It works by inhibiting DNA synthesis and cell proliferation in rapidly dividing keratinocytes, leading to a reduction in psoriatic lesions. *Vitiligo* - **PUVA therapy** is a common treatment for vitiligo, stimulating melanocyte activity and promoting repigmentation in affected areas. - Psoralen sensitizes melanocytes to UVA light, which then encourages melanin production. *Mycosis fungoides* - In its early stages, **mycosis fungoides**, a cutaneous T-cell lymphoma, can be effectively treated with **PUVA therapy**. - PUVA induces apoptosis of malignant T-cells in the skin, leading to remission of skin lesions.
Question 2: How does narrowband UVB therapy work in psoriasis?
- A. Melanin synthesis
- B. Collagen breakdown
- C. Keratinocyte proliferation
- D. T cell apoptosis (Correct Answer)
Explanation: ***T cell apoptosis*** - Narrowband UVB (NB-UVB) therapy primarily works by inducing **apoptosis (programmed cell death)** of activated **T-lymphocytes** in the psoriatic skin lesions. - By reducing the number of these inflammatory cells, NB-UVB helps to suppress the immune response that drives the **excessive keratinocyte proliferation** in psoriasis. *Melanin synthesis* - While UV radiation does stimulate **melanin synthesis**, leading to tanning, this is a secondary effect and not the primary therapeutic mechanism for psoriasis. - Increased melanin helps protect the skin from UV damage but does not directly treat the underlying pathology of psoriasis. *Collagen breakdown* - UV radiation, especially UVA, can contribute to **collagen breakdown** and photodamage over time, but this is an adverse effect, not a therapeutic mechanism for psoriasis. - Psoriasis treatment aims to normalize skin cell growth and reduce inflammation, not degrade collagen. *Keratinocyte proliferation* - Psoriasis is characterized by **accelerated keratinocyte proliferation**; NB-UVB therapy aims to *reduce* this proliferation, not promote it. - The mechanism by which NB-UVB achieves this reduction is primarily through its effects on immune cells, not by directly enhancing keratinocyte growth.
Question 3: All of the following are used in systemic therapy of psoriasis except
- A. Methotrexate
- B. Cyclosporine
- C. Oral glucocorticoids (Correct Answer)
- D. Acitretin
Explanation: ***Oral glucocorticoids*** - **Oral glucocorticoids** are generally avoided in psoriasis because they can precipitate severe **rebound flares** upon discontinuation or during dose tapering. - While they can temporarily suppress inflammation, the risk of worsening psoriasis and other systemic side effects makes them unsuitable for long-term systemic therapy. *Methotrexate* - **Methotrexate** is a commonly used systemic agent for psoriasis due to its **immunosuppressive** and **anti-proliferative effects**, targeting rapidly dividing cells. - It works by inhibiting dihydrofolate reductase and is typically given once weekly for chronic plaque psoriasis. *Cyclosporine* - **Cyclosporine** is an effective systemic immunosuppressant used for severe, resistant psoriasis, particularly when rapid control is needed. - It primarily acts by inhibiting **T-cell activation** and proliferation, thereby reducing the inflammatory response in psoriasis. *Acitretin* - **Acitretin** is an oral retinoid derivative of vitamin A, used in severe forms of psoriasis, especially **pustular** and **erythrodermic** types. - It works by modulating **keratinocyte differentiation** and proliferation, helping to normalize skin cell growth.
Question 4: Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?
- A. Cyclophosphamide
- B. Methotrexate
- C. Cisplatin (Correct Answer)
- D. Dacarbazine
Explanation: ***Cisplatin*** - **Cisplatin** is a platinum-based chemotherapy drug that forms **DNA cross-links**, inhibiting DNA synthesis and leading to the death of rapidly dividing cells, making it highly effective against **ovarian carcinoma**. - It is a cornerstone of chemotherapy regimens for ovarian cancer, often used in combination with other agents such as paclitaxel. *Methotrexate* - **Methotrexate** is an **antimetabolite** that inhibits dihydrofolate reductase, thereby interfering with DNA synthesis. - While it is used in various cancers like leukemia, lymphoma, and some solid tumors (e.g., breast cancer, gestational trophoblastic disease), it is **not a primary recommended drug for ovarian carcinoma**. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** that causes DNA damage, leading to cell death. - It is used in many cancers, including lymphoma, breast cancer, and some leukemias, but it is **not a first-line or primary agent for ovarian carcinoma** in contemporary treatment guidelines. *Dacarbazine* - **Dacarbazine** is an **alkylating agent** primarily used in the treatment of **malignant melanoma** and Hodgkin lymphoma. - It is **not indicated for the treatment of ovarian carcinoma**.
Question 5: Podophyllum resin is indicated in the treatment of:
- A. Pemphigus.
- B. Psoriasis.
- C. Condyloma acuminata. (Correct Answer)
- D. Condylomata lata.
Explanation: ***Condyloma acuminata.*** - **Podophyllum resin** is a cytotoxic agent that inhibits cell division and is commonly used as a topical treatment for **genital warts (condyloma acuminata)**. - Its mechanism involves arresting cells in metaphase by interfering with microtubule assembly, leading to necrosis of the wart tissue. *Pemphigus.* - **Pemphigus** is an autoimmune blistering disease of the skin and mucous membranes, not treated with podophyllum resin. - Treatment typically involves **systemic corticosteroids** and other immunosuppressive agents. *Psoriasis.* - **Psoriasis** is a chronic inflammatory skin condition characterized by accelerated epidermal cell turnover, and **podophyllum resin is not indicated for its treatment**. - Management often includes topical corticosteroids, vitamin D analogs, phototherapy, and systemic immunomodulators. *Condylomata lata.* - **Condylomata lata** are broad, flat, moist lesions characteristic of **secondary syphilis**, and they are highly infectious. - Treatment involves **penicillin** for syphilis, as condylomata lata are a manifestation of the underlying spirochete infection.
Question 6: Laser used in LASIK is:
- A. Excimer (Correct Answer)
- B. Argon
- C. Holmium
- D. Nd-yag
Explanation: ***Excimer*** - An **excimer laser** is used in LASIK procedures due to its ability to precisely ablate (remove) corneal tissue without causing thermal or collateral damage to surrounding tissues. - This laser operates in the **ultraviolet (UV) spectrum** and uses a mixture of inert and halogen gases (e.g., argon fluoride) to produce its beam. *Argon* - **Argon lasers** are primarily used for procedures involving the **retina and iris**, such as panretinal photocoagulation for diabetic retinopathy or iridotomy for narrow-angle glaucoma. - They emit light in the **visible blue-green spectrum**, which is absorbed by melanin and hemoglobin. *Holmium* - **Holmium lasers** are used in ophthalmology for procedures like **sclerostomy** (creating a drainage channel for glaucoma) or **transscleral cyclophotocoagulation**. - They operate in the **infrared spectrum** and are known for their strong tissue absorption and thermal effect. *Nd-yag* - A **Nd:YAG laser** is commonly used for **posterior capsulotomy** after cataract surgery to treat posterior capsular opacification, and for **peripheral iridotomy** in glaucoma. - It emits light in the **infrared spectrum** and works by creating photodisruption (plasma formation) to cut tissue without direct thermal effects.
Question 7: What is the best time to give oral psoralen with UVA -
- A. Half an hour after UVA
- B. 1 hour before UVA (Correct Answer)
- C. 1 hour after UVA
- D. Half hour before UVA
Explanation: ***1 hour before UVA*** - Oral psoralen, when used in **PUVA therapy**, requires adequate time for absorption and distribution to the skin to exert its photosensitizing effects. - Administering psoralen approximately **1-2 hours before UVA exposure** (typically 1.5-2 hours for 8-methoxypsoralen) ensures peak drug concentration in the skin, maximizing therapeutic efficacy. - Among the given options, **1 hour is the most appropriate timing** as it allows sufficient absorption while being closer to the therapeutic window than shorter intervals. *Half an hour after UVA* - Administering psoralen **after UVA exposure** would mean the photosensitizer is not present in sufficient concentrations during the light therapy. - This timing would render the UVA treatment largely ineffective as the primary mechanism of action, **photoreaction with UVA**, would not occur. *1 hour after UVA* - Giving psoralen **1 hour after UVA** completely misses the therapeutic window needed for the drug to photosensitize the skin during light exposure. - The UVA light would have already been administered without the active drug in the skin, thus providing **minimal to no therapeutic benefit**. *Half hour before UVA* - **Half an hour before UVA** is insufficient time for adequate oral absorption and distribution of psoralen to achieve optimal photosensitization. - This could result in **suboptimal drug concentration at the time of UVA exposure** and reduced therapeutic efficacy compared to the standard 1-2 hour pre-treatment timing.
Question 8: The laser procedure, most often used for treating iris neovascularization is
- A. Panretinal photocoagulation (PRP) (Correct Answer)
- B. Laser iridoplasty
- C. Laser trabeculoplasty
- D. Goniophotocoagulation
Explanation: ***Panretinal photocoagulation (PRP)*** - **PRP** is the most effective laser procedure for **iris neovascularization** and **neovascular glaucoma**, as it ablates the ischemic retina, reducing the production of **vascular endothelial growth factor (VEGF)**. - By destroying the ischemic peripheral retina, PRP reduces the **angiogenic drive** that leads to new vessel formation on the iris and in the angle. *Laser iridoplasty* - This procedure involves applying laser energy to the peripheral iris to cause contraction and widen the **anterior chamber angle**, primarily used for **angle-closure glaucoma**. - While it can open a closed angle, it does not address the underlying **ischemic drive** causing neovascularization. *Laser trabeculoplasty* - This procedure targets the **trabecular meshwork** to improve aqueous humor outflow, commonly used for **open-angle glaucoma**. - It does not directly affect **iris neovascularization** or the ischemic factors driving its development. *Goniophotocoagulation* - This involves directly lasering new vessels in the **anterior chamber angle**, often as an adjunct to PRP, but it's not the primary treatment to prevent **iris neovascularization**. - It treats existing vessels but does not address the underlying cause of **retinal ischemia** that promotes new vessel growth.
Question 9: A 45-day-old infant presents with seizures. Examination reveals he is icteric, has bulging fontanelles, and exhibits opisthotonic posture. Which of the following treatments is NOT indicated?
- A. Chlorpromazine (Correct Answer)
- B. Phenobarbital
- C. Phototherapy
- D. Exchange Transfusion
Explanation: ***Chlorpromazine*** - Chlorpromazine is an **antipsychotic medication** and is **contraindicated** in infants, especially in the presence of seizures and central nervous system (CNS) dysfunction, due to its potential to **lower the seizure threshold** and cause severe extrapyramidal symptoms. - Its mechanism of action via **dopamine receptor blockade** is not relevant for treating bilirubin encephalopathy or its symptoms. *Phototherapy* - Phototherapy is a primary treatment for **neonatal jaundice** to reduce unconjugated bilirubin levels and prevent neurotoxicity. - While the infant's condition suggests severe hyperbilirubinemia with complications, phototherapy would still be indicated as an initial step or adjunct to further interventions, especially if the bilirubin levels are still rising. *Exchange Transfusion* - Exchange transfusion is a **definitive treatment** for severe hyperbilirubinemia, especially when there are signs of **acute bilirubin encephalopathy (kernicterus)**, as suggested by seizures, bulging fontanelles, and opisthotonus. - It rapidly removes bilirubin from the blood and is crucial to prevent further neurological damage in such critical cases. *Phenobarbital* - Phenobarbital is an **anticonvulsant** used to manage seizures, which are a prominent symptom in this infant. - It can also help to **induce hepatic enzymes** involved in bilirubin metabolism, thereby potentially aiding in the reduction of bilirubin levels in cases of severe hyperbilirubinemia, though its primary role here would be seizure control.
Question 10: In a term baby who is 72 hours old, breastfeeding well, and has a bilirubin level of 14 mg/dL, which of the following statements is true?
- A. Exchange transfusion
- B. Continue to breastfeed (Correct Answer)
- C. Phototherapy
- D. None of the options
Explanation: ***Continue to breastfeed*** - A bilirubin level of **14 mg/dL at 72 hours of age** in a healthy, full-term, breastfeeding baby is usually within the range considered **physiological jaundice** and does not warrant stopping breastfeeding. - **Breastfeeding should continue** regardless of jaundice management, as interruption can cause a **decrease in milk supply** and may worsen jaundice by reducing bilirubin excretion through stool. - Continued breastfeeding (8-12 times per day) helps promote bilirubin clearance. *Exchange transfusion* - This is an **invasive procedure** reserved for very high bilirubin levels (typically **>20-25 mg/dL** in full-term infants depending on age and risk factors) or in cases of **acute bilirubin encephalopathy**. - A bilirubin level of 14 mg/dL is **well below the threshold** for exchange transfusion in a healthy term infant. *Phototherapy* - According to **AAP guidelines**, phototherapy thresholds are age-dependent: - At **72 hours of age**, phototherapy is typically considered at bilirubin levels **>15-18 mg/dL** in low-risk term infants. - At 14 mg/dL, **close monitoring** with repeat bilirubin measurement is appropriate, but phototherapy is generally **not yet indicated** for a healthy term infant without risk factors. *None of the options* - This option is incorrect because **continuing to breastfeed** is the appropriate and evidence-based management for this clinical scenario. - The other interventions (exchange transfusion, phototherapy) are **not indicated** at this bilirubin level and age in a healthy term infant.
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