DRESS syndrome and severe cutaneous reactions US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for DRESS syndrome and severe cutaneous reactions. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 1: A 10-year-old boy presents with a painful rash for 1 day. He says that the reddish, purple rash started on his forearm but has now spread to his abdomen. He says there is a burning pain in the area where the rash is located. He also says he has had a stuffy nose for several days. Past medical history is significant for asthma and epilepsy, medically managed. Current medications are a daily chewable multivitamin, albuterol, budesonide, and lamotrigine. On physical examination, there is a red-purple maculopapular rash present on upper extremities and torso. There are some blisters present over the rash, as shown in the image, which is also present in the oral mucosa. Which of the following is the most likely cause of this patient’s symptoms?
- A. Multivitamin
- B. Budesonide
- C. Albuterol
- D. Lamotrigine (Correct Answer)
- E. Infection
DRESS syndrome and severe cutaneous reactions Explanation: ***Lamotrigine***
- The patient's symptoms, including a **painful, rapidly spreading maculopapular rash** with **blisters** involving the skin and **oral mucosa**, are highly suggestive of **Stevens-Johnson Syndrome (SJS)** or **toxic epidermal necrolysis (TEN)**.
- **Lamotrigine** is a known medication commonly associated with SJS/TEN, especially when initiated or titrated rapidly.
*Multivitamin*
- **Multivitamins** are generally safe and are not known to cause severe dermatological reactions like SJS/TEN.
- While allergic reactions to specific components in multivitamins are possible, they are typically mild and do not present with widespread blistering rashes.
*Budesonide*
- **Budesonide** is an inhaled corticosteroid primarily used for asthma and is not associated with SJS/TEN.
- Corticosteroids are more commonly used *to treat* inflammatory skin conditions rather than cause them.
*Albuterol*
- **Albuterol** is a bronchodilator for asthma and is not a recognized cause of SJS/TEN.
- Adverse effects of albuterol are typically cardiac (e.g., tachycardia) or neurological (e.g., tremor).
*Infection*
- While some **infections** (e.g., *Mycoplasma pneumoniae*, herpes simplex virus) can trigger SJS, the abrupt onset of symptoms in a patient on a high-risk medication makes the drug the more likely primary cause.
- The "stuffy nose" could be an upper respiratory infection, which can sometimes precede SJS, but the distinctive rash and medication history strongly point to lamotrigine as the precipitating factor.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 2: A 42-year-old man who is employed as a construction worker presents to his primary care physician with complaints of moderate headaches and profuse sweating. He reports the need to carry up to 3 additional shirt changes to work because they drench quickly even with tasks of low physical exertion. His coworkers have commented about his changing glove and boot sizes, which have increased at least 4 times since he joined the company 10 years ago. Physical examination is unremarkable except for blood pressure of 160/95 mm Hg, hyperhidrosis, noticeably large pores, hypertrichosis, widely spaced teeth, and prognathism. Which of the following best explains the patient’s clinical manifestations?
- A. Increased serum cortisol
- B. Increased thyroid-stimulating hormone
- C. Increased serum metanephrines
- D. Increased serum insulin-like growth factor 1 (IGF-1) (Correct Answer)
- E. Increased serum testosterone
DRESS syndrome and severe cutaneous reactions Explanation: ***Increased serum insulin-like growth factor 1 (IGF-1)***
- Elevated **IGF-1** levels are indicative of **acromegaly**, a condition caused by excess growth hormone (GH) secretion, which explains the gradual changes in glove and boot sizes, prognathism, widely spaced teeth, and large pores.
- The symptoms of **profuse sweating**, **hypertrichosis**, **headaches**, and **hypertension** are common clinical manifestations of acromegaly due to the systemic effects of chronic GH excess.
*Increased serum cortisol*
- **Increased cortisol** (Cushing's syndrome) would present with central obesity, moon facies, buffalo hump, and striae, which are not described in the patient.
- While hypertension and hyperhidrosis can occur in Cushing's, the characteristic physical changes related to growth are absent.
*Increased thyroid-stimulating hormone*
- Elevated **TSH** suggests **hypothyroidism**, which would typically cause fatigue, weight gain, cold intolerance, and bradycardia, rather than profuse sweating and hypertension.
- **Hyperthyroidism** (low TSH, high thyroid hormones) can cause sweating and hypertension, but it would not explain the gradual increase in body and appendage size.
*Increased serum metanephrines*
- Elevated **metanephrines** are a hallmark of **pheochromocytoma**, which typically presents with paroxysmal episodes of hypertension, palpitations, and sweating.
- While sweating and hypertension are present, the absence of episodic symptoms and the long-term changes in body size make pheochromocytoma less likely.
*Increased serum testosterone*
- **Increased testosterone** in a male would typically lead to increased muscle mass, acne, and potentially male-pattern baldness, but not the specific skeletal and soft tissue growth patterns observed, such as increased shoe and glove size or prognathism.
- While some skin changes might occur, **hyperhidrosis** and the dramatic facial and extremity changes are not characteristic features of testosterone excess.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 3: A 13-year-old boy is brought to the emergency department because of vomiting, diarrhea, abdominal pain, and dizziness for the past 3 hours with fever, chills, and muscle pain for the last day. He had presented 5 days ago for an episode of epistaxis caused by nasal picking and was treated with placement of anterior nasal packing. His parents report that the bleeding stopped, but they forgot to remove the nasal pack. His temperature is 40.0°C (104.0°F), pulse is 124/min, respirations are 28/min, and blood pressure is 96/68 mm Hg. He looks confused, and physical exam shows conjunctival and oropharyngeal hyperemia with a diffuse, erythematous, macular rash over the body that involves the palms and the soles. Removal of the anterior nasal pack shows hyperemia with purulent discharge from the underlying mucosa. Laboratory studies show:
Total white blood cell count 30,000/mm3 (30 x 109/L)
Differential count
Neutrophils 90%
Lymphocytes 8%
Monocytes 1%
Eosinophils 1%
Basophils 0%
Platelet count 95,000/mm3 (95 x 109/L)
Serum creatine phosphokinase 400 IU/L
What is the most likely diagnosis for this patient?
- A. Stevens-Johnson syndrome
- B. Measles
- C. Disseminated gonococcal infection
- D. Herpes simplex virus type 2 (HSV-2) meningitis
- E. Toxic shock syndrome (Correct Answer)
DRESS syndrome and severe cutaneous reactions Explanation: ***Toxic shock syndrome***
- The patient's presentation with **fever**, **hypotension**, **diffuse erythematous rash** involving palms/soles, **multisystem involvement** (vomiting, diarrhea, dizziness, confusion, elevated CPK), and the history of prolonged **nasal packing** (a common nidus for *Staphylococcus aureus* toxin production) is highly characteristic of **toxic shock syndrome (TSS)**.
- **Leukocytosis with neutrophilia** and **thrombocytopenia** are also common laboratory findings in TSS.
*Stevens-Johnson syndrome*
- Characterized by **mucocutaneous lesions** with epidermal detachment, forming **bullae** and **erosions**, often preceded by fever and flu-like symptoms.
- While it can involve mucous membranes, the **diffuse erythematous macular rash without bullae** and the rapid development of **shock** are not typical features.
*Measles*
- Presents with a **maculopapular rash** that typically starts on the face and spreads downwards, often coalescing. It is preceded by **prodromal symptoms** like cough, coryza, conjunctivitis, and **Koplik spots**.
- **Hypotension**, **severe multiorgan dysfunction**, and **nasal packing as a risk factor** are not features of measles.
*Disseminated gonococcal infection*
- Can cause **fever**, migratory **polyarthralgia**, and a **pustular or vesiculopustular rash** with hemorrhagic lesions, primarily on the extremities.
- The described **diffuse erythematous macular rash**, severe hypotension, and history of nasal packing do not fit the typical presentation of disseminated gonococcal infection.
*Herpes simplex virus type 2 (HSV-2) meningitis*
- Primarily causes **aseptic meningitis** with symptoms like fever, headache, stiff neck, and photophobia.
- It does not explain the **diffuse erythematous rash**, **hypotension**, **multisystem involvement**, or the role of **nasal packing** in the patient's presentation.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 4: A 47-year-old man presents to the emergency department due to a rash. He states the rash started last night and is very concerning to him. The patient cannot remember being exposed to any environmental stimuli such as new detergents or poison ivy. The patient recently started following with a primary care provider who is helping him manage his arthritis and a new onset cough. His temperature is 99.5°F (37.5°C), blood pressure is 127/68 mmHg, pulse is 125/min, respirations are 18/min, and oxygen saturation is 98% on room air. Physical exam is notable for the findings of coalescing erythematous macules, bullae, desquamation, and mucositis only on the upper half of his back. Cardiopulmonary exam and abdominal exam are within normal limits. Inspection of the patient’s oropharynx reveals ulcers and erythema. Which of the following is the most likely diagnosis?
- A. Stevens-Johnson syndrome (Correct Answer)
- B. Erythema multiforme
- C. Herpes zoster
- D. Herpes simplex virus
- E. Toxic epidermal necrolysis
DRESS syndrome and severe cutaneous reactions Explanation: ***Stevens-Johnson syndrome***
- This patient presents with a **rash of coalescing erythematous macules, bullae, desquamation, and mucositis in the oropharynx**, which are characteristic of SJS.
- The recent initiation of new medication for arthritis and a cough suggests a **drug-induced etiology**, a common trigger for SJS.
*Erythema multiforme*
- While erythema multiforme can present with a rash and some **mucosal involvement**, it typically manifests with **targetoid lesions** (target lesions with distinct rings), which are not described here.
- It is generally a less severe condition than SJS and typically involves less extensive skin detachment.
*Herpes zoster*
- Herpes zoster (shingles) presents as a **unilateral, dermatomal rash** of vesicles on an erythematous base, often accompanied by pain and itching.
- The described rash is **diffuse and coalescing**, not dermatomal, making herpes zoster unlikely.
*Herpes simplex virus*
- Herpes simplex virus (HSV) typically causes **localized clusters of vesicles** on an erythematous base, most commonly around the mouth (cold sores) or genitals.
- The extensive, diffuse rash with desquamation and bullae is inconsistent with typical HSV infection.
*Toxic epidermal necrolysis*
- **Toxic epidermal necrolysis (TEN)** is a more severe form of SJS, often considered a continuum of the same disease, but it involves **>30% body surface area** skin detachment.
- The patient's rash is noted "only on the upper half of his back," suggesting less extensive involvement than typically seen in TEN.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 5: A 10-year-old boy from Sri Lanka suffers from an autosomal dominant condition, the hallmark of which is hyperimmunoglobulinemia E and eosinophilia. He suffers from recurrent infections and takes antibiotic chemoprophylaxis. A STAT3 mutation analysis has been performed to confirm the diagnosis of Job syndrome.
I. Eosinophilia
II. Eczema
III. Hay fever
IV. Atopic dermatitis
V. Recurrent skin and lung infections
VI. Bronchial asthma
What combination of symptoms above is characteristic of this condition?
- A. I, II, III
- B. I, II, IV, V
- C. I, III, IV
- D. I, II, V (Correct Answer)
- E. IV, V, VI
DRESS syndrome and severe cutaneous reactions Explanation: ***I, II, V***
- **Job syndrome** (Hyper-IgE syndrome) is characterized by a triad of **recurrent infections** (recurrent skin and lung infections), **severe eczema**, and **eosinophilia**.
- The patient's presentation with hyperimmunoglobulinemia E, eosinophilia, and recurrent infections, coupled with a confirmed **STAT3 mutation**, directly aligns with the key features of this syndrome.
*I, II, III*
- While **eosinophilia** and **eczema** are characteristic of Job syndrome, **hay fever** (allergic rhinitis) is not a primary diagnostic criterion, although allergic manifestations can occur.
- The core clinical presentation focuses on immune dysregulation leading to infections and severe skin involvement, which are more specific than hay fever.
*I, II, IV, V*
- This option includes **atopic dermatitis** which is essentially synonymous with **eczema**, leading to redundancy.
- The combination should focus on distinct major clinical features rather than overlapping terms.
*I, III, IV*
- This option includes **hay fever** and **atopic dermatitis**, neither of which are as central to the diagnostic criteria as recurrent infections.
- The most critical elements for diagnosis are the immune dysfunction leading to severe infections and the hallmark skin condition.
*IV, V, VI*
- This option lists **atopic dermatitis**, **recurrent skin and lung infections**, and **bronchial asthma**. While these can be seen in Job syndrome, it omits **eosinophilia**, which is a defining laboratory finding.
- **Bronchial asthma** is also not a primary diagnostic feature, and the absence of eosinophilia makes this option less accurate.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 6: One week after starting a new medication, a 16-year-old girl is brought to the emergency department by her mother because of a painful, blistering rash. She has a history of bipolar disorder. Her temperature is 39°C (102°F). Physical examination shows numerous coalescing bullae with epidermal detachment covering the face, trunk, and extremities. There are hemorrhagic erosions on the hard palate and buccal mucosa. When lateral pressure is applied to healthy-appearing skin at the edge of a bulla, a blister starts to form. Which of the following drugs is most likely responsible for this patient's current condition?
- A. Valproic acid
- B. Lithium
- C. Quetiapine
- D. Topiramate
- E. Lamotrigine (Correct Answer)
DRESS syndrome and severe cutaneous reactions Explanation: ***Lamotrigine***
- The patient's symptoms (painful, blistering rash, coalescing bullae with epidermal detachment, hemorrhagic erosions on mucous membranes, fever, and positive **Nikolsky sign**) are classic for **Stevens-Johnson syndrome (SJS)** or **Toxic Epidermal Necrolysis (TEN)**.
- **Lamotrigine** is a mood stabilizer commonly used in bipolar disorder and is a well-known high-risk drug for inducing SJS/TEN, especially when initiated rapidly or at high doses.
*Valproic acid*
- While used in bipolar disorder, **valproic acid** is generally not associated with a high risk of SJS/TEN.
- Its common dermatological side effects are usually more benign, such as **alopecia** or **mild rash**, not severe blistering.
*Lithium*
- **Lithium** is a mood stabilizer for bipolar disorder, but it is rarely implicated in severe cutaneous adverse reactions like SJS/TEN.
- Dermatologic side effects of lithium are typically mild, including **acneiform eruptions** or **psoriasiform rashes**.
*Quetiapine*
- **Quetiapine** is an antipsychotic sometimes used in bipolar disorder, but it has a low risk of causing SJS/TEN compared to lamotrigine.
- While any drug can theoretically cause severe reactions, quetiapine is not a primary suspect for this presentation.
*Topiramate*
- **Topiramate** can cause various dermatological side effects, but it is not as strongly linked to SJS/TEN as lamotrigine.
- Its use for bipolar disorder is often off-label, and its most serious skin reactions are less common than with specific anticonvulsants.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 7: A 55-year-old male presents with complaints of intermittent facial flushing. He also reports feeling itchy after showering. On review of systems, the patient says he has been having new onset headaches recently. On physical exam, his vital signs, including O2 saturation, are normal. He has an abnormal abdominal mass palpable in the left upper quadrant. A complete blood count reveals: WBCs 6500/microliter; Hgb 18.2 g/dL; Platelets 385,000/microliter. Which of the following is most likely responsible for his presentation?
- A. BCR-ABL fusion
- B. Chronic hypoxemia
- C. Tyrosine kinase mutation (Correct Answer)
- D. Fibrosis of bone marrow
- E. Elevated serum erythropoietin levels
DRESS syndrome and severe cutaneous reactions Explanation: ***Tyrosine kinase mutation***
- The patient's symptoms (facial flushing, post-showering pruritus, headaches) along with **elevated hemoglobin** (18.2 g/dL) and **splenomegaly** (abdominal mass in LUQ) strongly suggest **Polycythemia Vera (PV)**.
- PV is a **myeloproliferative neoplasm** typically caused by a **JAK2 V617F mutation**, which is a type of **tyrosine kinase mutation**, leading to constitutive activation of the JAK-STAT pathway and uncontrolled erythropoiesis.
*BCR-ABL fusion*
- A **BCR-ABL fusion gene** is characteristic of **Chronic Myeloid Leukemia (CML)**, which typically presents with markedly elevated WBCs and splenomegaly.
- While splenomegaly is present here, the patient's symptoms and hematologic findings (elevated Hgb, normal WBCs) are not consistent with CML.
*Chronic hypoxemia*
- **Chronic hypoxemia** can cause **secondary erythrocytosis** due to increased erythropoietin production in response to low oxygen levels.
- However, the patient's **O2 saturation is normal**, ruling out chronic hypoxemia as the cause of his elevated hemoglobin.
*Fibrosis of bone marrow*
- **Bone marrow fibrosis** is a hallmark of **Primary Myelofibrosis**, another myeloproliferative neoplasm, which typically presents with anemia, marked splenomegaly, and teardrop cells on peripheral smear.
- While it can manifest with constitutional symptoms, the patient's **high hemoglobin** and absent anemia make primary myelofibrosis less likely.
*Elevated serum erythropoietin levels*
- **Elevated serum erythropoietin (EPO) levels** are characteristic of **secondary erythrocytosis**, where EPO production increases due to conditions like hypoxemia, renal tumors, or exogenous EPO use.
- In **Polycythemia Vera**, EPO levels are typically **low or undetectable** due to feedback inhibition from the high red blood cell mass.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 8: A 19-year-old man with a history of generalized tonic-clonic seizures comes to the physician for a routine health maintenance examination. He is a known user of intravenous cocaine. His vital signs are within normal limits. Physical examination shows multiple hyperpigmented lines along the forearms. Oral examination shows marked overgrowth of friable, ulcerated gingival mucosa. Which of the following is the most likely cause of this patient's oral examination findings?
- A. Cyclosporine
- B. Lacosamide
- C. Carbamazepine
- D. Phenytoin (Correct Answer)
- E. Lamotrigine
DRESS syndrome and severe cutaneous reactions Explanation: ***Phenytoin***
- **Phenytoin** is a common cause of **gingival hyperplasia**, presenting with marked overgrowth of friable, ulcerated gingival mucosa due to its effect on fibroblast proliferation and collagen production.
- This medication is frequently used to manage **tonic-clonic seizures**, consistent with the patient's history.
*Cyclosporine*
- While **cyclosporine** can cause **gingival hyperplasia**, it is an **immunosuppressant** primarily used in organ transplantation or autoimmune conditions, which is not indicated in the patient's seizure history.
- The patient's presentation does not suggest any condition for which cyclosporine would be prescribed.
*Lacosamide*
- **Lacosamide** is an anticonvulsant that stabilizes hyperexcitable neuronal membranes, but it is **not typically associated with gingival hyperplasia**.
- Its known side effects are primarily neurological, such as dizziness, headache, and nausea.
*Carbamazepine*
- **Carbamazepine** is an anticonvulsant effective for focal and tonic-clonic seizures, but **gingival hyperplasia is a rare side effect** with this medication.
- More common side effects include dizziness, drowsiness, and bone marrow suppression.
*Lamotrigine*
- **Lamotrigine** is an anticonvulsant used for various seizure types, but **gingival hyperplasia is not a recognized side effect**.
- It is more commonly associated with skin rashes, including severe reactions like **Stevens-Johnson syndrome**.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 9: A 3-year-old boy presents to the emergency department with a fever and a rash. This morning the patient was irritable and had a fever which gradually worsened throughout the day. He also developed a rash prior to presentation. He was previously healthy and is not currently taking any medications. His temperature is 102.0°F (38.9°C), blood pressure is 90/50 mmHg, pulse is 160/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a scarlatiniform rash with flaccid blisters that rupture easily, covering more than 60% of the patient’s body surface. The lesions surround the mouth but do not affect the mucosa, and palpation of the rash is painful. Which of the following is the most likely diagnosis?
- A. Staphylococcal scalded skin syndrome (Correct Answer)
- B. Toxic epidermal necrolysis
- C. Toxic shock syndrome
- D. Urticaria
- E. Stevens Johnson syndrome
DRESS syndrome and severe cutaneous reactions Explanation: ***Staphylococcal scalded skin syndrome***
- The presentation of a **fever**, **irritability**, and a **scarlatiniform rash with flaccid blisters** that rupture easily, especially with painful lesions and perioral involvement without mucosal lesions, is highly characteristic of **Staphylococcal scalded skin syndrome (SSSS)**.
- SSSS is caused by **exfoliative toxins** produced by *Staphylococcus aureus*, which target **desmoglein-1** in the skin, leading to widespread superficial blistering and epidermal sloughing.
*Toxic epidermal necrolysis*
- **Toxic epidermal necrolysis (TEN)** is a severe mucocutaneous reaction often triggered by **medications**, characterized by widespread **epidermal detachment (>30% BSA)** and **mucosal involvement**.
- TEN typically presents with full-thickness epidermal necrosis and severe systemic symptoms, often after drug exposure, which is not noted in this previously healthy, non-medicated child.
*Toxic shock syndrome*
- **Toxic shock syndrome (TSS)** is characterized by **fever**, **hypotension**, **diffuse erythematous rash**, and **multisystem organ dysfunction**.
- While a rash and fever are present, the hallmark **flaccid blistering** and **skin peeling** seen in SSSS is not typical for TSS; TSS rash is more often a blanching erythroderma.
*Urticaria*
- **Urticaria (hives)** presents as **pruritic, transient, raised erythematous wheals** that blanch with pressure.
- The rash in this patient is described as **scarlatiniform with flaccid blisters** and is painful, which is inconsistent with the typical appearance and symptoms of urticaria.
*Stevens Johnson syndrome*
- **Stevens-Johnson syndrome (SJS)** is a severe adverse drug reaction, similar to TEN but with less extensive skin involvement (**<10% BSA**), and is characterized by **erythematous macules**, **targetoid lesions**, and **mucosal involvement**.
- While blistering can occur, the widespread, painful, easily rupturing flaccid blisters without specific target lesions and prominent perioral involvement (without mucosal affection) point more strongly to SSSS over SJS.
DRESS syndrome and severe cutaneous reactions US Medical PG Question 10: A 52-year-old man presents for a routine checkup. Past medical history is remarkable for stage 1 systemic hypertension and hepatitis A infection diagnosed 10 years ago. He takes aspirin, rosuvastatin, enalapril daily, and a magnesium supplement every once in a while. He is planning to visit Ecuador for a week-long vacation and is concerned about malaria prophylaxis before his travel. The physician advised taking 1 primaquine pill every day while he is there and for 7 consecutive days after leaving Ecuador. On the third day of his trip, the patient develops an acute onset headache, dizziness, shortness of breath, and fingertips and toes turning blue. His blood pressure is 135/80 mm Hg, heart rate is 94/min, respiratory rate is 22/min, temperature is 36.9℃ (98.4℉), and blood oxygen saturation is 97% in room air. While drawing blood for his laboratory workup, the nurse notes that his blood has a chocolate brown color. Which of the following statements best describes the etiology of this patient’s most likely condition?
- A. The patient’s condition is due to consumption of water polluted with nitrates.
- B. The patient had pre-existing liver damage caused by viral hepatitis.
- C. This condition resulted from primaquine overdose.
- D. It is a type B adverse drug reaction. (Correct Answer)
- E. The condition developed because of his concomitant use of primaquine and magnesium supplement.
DRESS syndrome and severe cutaneous reactions Explanation: ***It is a type B adverse drug reaction.***
- The patient's symptoms (headache, dizziness, shortness of breath, cyanosis, chocolate brown blood) are consistent with **methemoglobinemia**, which is a known idiosyncratic reaction to **primaquine**. Type B adverse drug reactions are **unpredictable** and not dose-dependent, representing an individual's unique response to a drug.
- This reaction likely stems from an underlying **glucose-6-phosphate dehydrogenase (G6PD) deficiency**, making him susceptible to oxidative stress induced by primaquine, leading to methemoglobin formation. The occurrence of symptoms early in the course of medication (3rd day) also supports an idiosyncratic reaction rather than a typical dose-related effect.
*The patient’s condition is due to consumption of water polluted with nitrates.*
- While **nitrate poisoning** can cause methemoglobinemia, the patient’s symptoms appeared shortly after starting primaquine for malaria prophylaxis, making drug-induced methemoglobinemia a more direct and probable cause in this clinical context.
- Exposure to nitrate-polluted water is unlikely to cause a sudden onset of such severe symptoms within 3 days of arrival, especially considering he is taking a known oxidizing agent (primaquine).
*The patient had pre-existing liver damage caused by viral hepatitis.*
- Although **liver dysfunction** can alter drug metabolism, hepatitis A is an acute infection that does not typically cause chronic liver damage leading to altered drug metabolism for primaquine in the long term, especially 10 years after diagnosis.
- The primary risk factor for primaquine-induced methemoglobinemia is G6PD deficiency, not liver damage, which affects red blood cell susceptibility to oxidative stress.
*This condition resulted from primaquine overdose.*
- The prescribed dose of primaquine (one pill daily) is standard for malaria prophylaxis, and there is no indication the patient took more than prescribed. This reaction is likely due to an **idiosyncratic response** rather than an excessive dose.
- Methemoglobinemia from primaquine is often seen in individuals with **G6PD deficiency** even at therapeutic doses, making it an unpredictable Type B adverse reaction rather than a direct dose-dependent toxicity.
*The condition developed because of his concomitant use of primaquine and magnesium supplement.*
- There is no known direct significant **drug interaction** between primaquine and magnesium supplements that would lead to methemoglobinemia.
- The underlying cause of methemoglobinemia with primaquine is typically due to its **oxidative properties** in susceptible individuals (e.g., G6PD deficiency), not an interaction with magnesium.
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