UVA and UVB Phototherapy — MCQs
A 40 year old woman presents with a 2 year history of erythematous papulopustular lesions on convexities of the face. There is a background of erythema & telangiectasia. The most likely diagnosis is –
Which one of these should not be used in severe widespread psoriasis?
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
Assertion: Vitamin D analogues are effective in psoriasis. Reason: They reduce keratinocyte proliferation
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?
Which of the following is NOT a complication of PUVA therapy?
A 12-year-old boy, after spending his holiday on a beach, develops pruritic hemorrhagic vesicles on his cheeks, ears, nose, and hands 12 hours after sun exposure. A week later, the lesions crusted and healed with permanent scars. What is the most probable diagnosis?
UVA and UVB Phototherapy Indian Medical PG Practice Questions and MCQs
Question 1: A 40 year old woman presents with a 2 year history of erythematous papulopustular lesions on convexities of the face. There is a background of erythema & telangiectasia. The most likely diagnosis is –
- A. Polymorphic light eruption
- B. Acne vulgaris
- C. Acne rosacea (Correct Answer)
- D. SLE
Explanation: ***Acne rosacea*** - This condition presents with **erythematous papulopustular lesions**, background **erythema**, and **telangiectasias** predominantly on the convexities of the face, which is a classic presentation for rosacea. - The absence of **comedones** (blackheads/whiteheads) helps differentiate it from acne vulgaris. *Polymorphic light eruption* - This is a recurring skin rash triggered by **sun exposure**, presenting as itchy papules, plaques, or vesicles, usually appearing a few hours after exposure. - Unlike rosacea, it does not typically feature permanent facial erythema or telangiectasias and is more directly linked to UV exposure episodes. *Acne vulgaris* - While it features papules and pustules, **acne vulgaris** is characterized by the presence of **comedones** (blackheads and whiteheads), which are not described in the patient's presentation. - It also does not typically involve the prominent background erythema and telangiectasias seen in rosacea. *SLE* - Systemic lupus erythematosus (SLE) can cause a **malar or 'butterfly' rash** across the nose and cheeks, but it is typically a fixed erythema, sometimes with scaling, and does not usually involve papulopustular lesions or telangiectasias as a primary feature. - SLE often has systemic symptoms (e.g., joint pain, fatigue) that are not mentioned, and skin lesions can be photosensitive but are not typically pustular.
Question 2: Which one of these should not be used in severe widespread psoriasis?
- A. Methotrexate
- B. Oral retinoids
- C. Cyclosporin
- D. Oral glucocorticoids (Correct Answer)
Explanation: ***Oral glucocorticoids*** - While they may provide temporary relief, **oral glucocorticoids** can exacerbate psoriasis upon withdrawal, leading to a severe flare-up or **pustular psoriasis**. - Their long-term use is associated with numerous side effects, making them unsuitable for widespread, chronic conditions like severe psoriasis. *Methotrexate* - **Methotrexate** is a systemic agent commonly used for severe psoriasis due to its immune-modulating and anti-proliferative effects. - It is effective in reducing inflammation and slowing down epidermal cell turnover. *Oral retinoids* - **Oral retinoids** like acitretin are effective systemic treatments for severe widespread psoriasis, especially **pustular** and **erythrodermic** forms. - They work by normalizing keratinocyte proliferation and differentiation. *Cyclosporin* - **Cyclosporin** is a potent immunosuppressant widely used for severe psoriasis, particularly when rapid disease control is needed. - It works by inhibiting T-cell activation and is highly effective in clearing psoriatic lesions.
Question 3: 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 4: 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 5: 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 6: Assertion: Vitamin D analogues are effective in psoriasis. Reason: They reduce keratinocyte proliferation
- A. Both A & R true, R explains A (Correct Answer)
- B. A false R true
- C. Both A & R true, R doesn't explain A
- D. A true R false
Explanation: ***Both A & R true, R explains A*** - **Vitamin D analogues** (e.g., calcipotriol) are a cornerstone treatment for psoriasis because they effectively modulate **keratinocyte proliferation** and differentiation. - Psoriasis is characterized by the **rapid overgrowth of keratinocytes**, and the antiproliferative effects of vitamin D analogues directly address this pathological hallmark. *A false R true* - This option is incorrect because both the assertion (Vitamin D analogues are effective in psoriasis) and the reason (They reduce keratinocyte proliferation) are individually true. - The effectiveness of vitamin D analogues in treating psoriasis is well-established in dermatological practice. *Both A & R true, R doesn't explain A* - This option is incorrect because the reduction of keratinocyte proliferation is precisely *how* vitamin D analogues exert their therapeutic effect in psoriasis. - The mechanism of action described in the reason directly explains the efficacy mentioned in the assertion. *A true R false* - This option is incorrect because the reason ("They reduce keratinocyte proliferation") is a fundamental and well-understood mechanism by which vitamin D analogues work in psoriasis. - Vitamin D analogues bind to vitamin D receptors in keratinocytes, influencing gene expression to inhibit their excessive growth.
Question 7: 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 8: 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.
Question 9: Which of the following is NOT a complication of PUVA therapy?
- A. Premature aging of the skin
- B. Cataracts
- C. Skin cancers
- D. Exfoliative dermatitis (Correct Answer)
Explanation: **Explanation:** PUVA (Psoralen + Ultraviolet A) therapy involves the administration of a photosensitizer (8-methoxypsoralen) followed by exposure to UVA radiation. While it is an effective treatment for conditions like psoriasis and vitiligo, it carries specific long-term and short-term risks. **Why Exfoliative Dermatitis is the correct answer:** Exfoliative dermatitis (Erythroderma) is **not** a direct complication of PUVA. In fact, PUVA is often used as a *treatment* modality for certain types of exfoliative dermatitis, such as those caused by Mycosis Fungoides or Psoriasis. While PUVA can cause a "PUVA itch" or a phototoxic burn (erythema), it does not typically trigger generalized exfoliation. **Analysis of Incorrect Options:** * **Premature aging of the skin (Dermatoheliosis):** Chronic UVA exposure leads to the degradation of collagen and elastin fibers, resulting in wrinkles, lentigines, and telangiectasia. * **Cataracts:** Psoralens distribute to the lens of the eye. If the eyes are not protected with UVA-blocking sunglasses for 24 hours post-ingestion, UVA exposure can lead to lens opacification. * **Skin cancers:** PUVA is mutagenic. Long-term therapy significantly increases the risk of Non-Melanoma Skin Cancers (NMSC), particularly **Squamous Cell Carcinoma (SCC)**. **High-Yield Clinical Pearls for NEET-PG:** * **Most common acute side effect:** Erythema (phototoxicity) and pruritus. * **Most common long-term risk:** Squamous Cell Carcinoma (SCC) is more common than Basal Cell Carcinoma (BCC) in PUVA patients (reversing the usual ratio). * **PUVA Lentigines:** Distinctive, irregular pigmented macules that appear after chronic therapy. * **Contraindications:** Pregnancy, lactation, history of skin cancer (Xeroderma Pigmentosum), and severe hepatic/renal failure.
Question 10: A 12-year-old boy, after spending his holiday on a beach, develops pruritic hemorrhagic vesicles on his cheeks, ears, nose, and hands 12 hours after sun exposure. A week later, the lesions crusted and healed with permanent scars. What is the most probable diagnosis?
- A. Polymorphic light eruption
- B. Hydroa vacciniforme (Correct Answer)
- C. Actinic prurigo
- D. Persistent light reaction
Explanation: **Explanation:** The clinical presentation of a young boy with **hemorrhagic vesicles** on sun-exposed areas (cheeks, ears, nose, hands) that heal with **permanent scarring** (varioliform scars) is pathognomonic for **Hydroa vacciniforme (HV)**. **Why Hydroa vacciniforme is correct:** HV is a rare, chronic photodermatosis primarily affecting children. It is triggered by UVA radiation. The hallmark is the progression from erythema to vesicles/bullae, which become umbilicated and hemorrhagic, eventually forming necrotic crusts. The defining feature for NEET-PG is the healing process, which results in **depressed, "vacciniform" (smallpox-like) scars**. It is often associated with **Epstein-Barr Virus (EBV)** infection. **Why other options are incorrect:** * **Polymorphic Light Eruption (PMLE):** The most common photodermatosis. While it causes pruritic papules or vesicles, it **never heals with scarring**. * **Actinic Prurigo:** A variant of PMLE common in Native Americans. It presents with intensely pruritic, excoriated papules and nodules, often involving the lips (cheilitis) and conjunctiva, but does not typically present with hemorrhagic vesicles and varioliform scarring. * **Persistent Light Reaction:** Now classified under Chronic Actinic Dermatitis. It is an eczematous reaction seen in elderly males, where skin remains sensitive to light even without allergen exposure. **High-Yield Clinical Pearls for NEET-PG:** * **Action Spectrum:** UVA is the primary trigger for HV. * **Association:** Severe, systemic cases of HV are linked to **EBV-associated T-cell lymphoproliferative disorders**. * **Differential Diagnosis:** Must be distinguished from Erythropoietic Protoporphyria (EPP), which presents with immediate burning pain and waxy scarring, but lacks the hemorrhagic bullae of HV. * **Management:** Strict photoprotection; severe cases may require antimalarials or immunosuppressants.
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