Question:
An 8 year old boy completed 8 out of a 10 day course of cefaclor. He now develops a generalized erythematous rash that is mildly pruritic along with lymphadenopathy. The diagnosis is?
An 8 year old boy completed 8 out of a 10 day course of cefaclor. He now develops a generalized erythematous rash that is mildly pruritic along with lymphadenopathy. The diagnosis is?
Show Hint
A delayed itchy rash with lymphadenopathy after cefaclor is a serum-sickness-like, immune-complex reaction.
Updated On: Jun 24, 2026
- Kawasaki disease
- Type III hypersensitivity
- Anaphylaxis
- Infectious mononucleosis
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Note the timing. Symptoms appear about a week into a cefaclor course, not within minutes. A delayed onset of roughly 7 to 14 days after drug exposure points to a serum-sickness-like reaction.
Step 2: Cefaclor is the classic cause of serum-sickness-like reactions in children, presenting with rash, pruritus, fever, arthralgia and lymphadenopathy.
Step 3: Serum sickness is mediated by circulating antigen-antibody immune complexes that deposit in tissues and activate complement. This is the definition of a Type III hypersensitivity reaction.
Step 4: Rule out the others. Anaphylaxis is Type I, occurring within minutes with bronchospasm and hypotension, not a delayed rash. Kawasaki disease requires prolonged fever with mucocutaneous and conjunctival changes, not a drug trigger. Infectious mononucleosis is an EBV infection; its rash typically follows ampicillin or amoxicillin, not cefaclor, and it is not the underlying immune mechanism asked here.
Conclusion: The reaction is a Type III (immune complex) hypersensitivity, so the answer is option 2.
Step 2: Cefaclor is the classic cause of serum-sickness-like reactions in children, presenting with rash, pruritus, fever, arthralgia and lymphadenopathy.
Step 3: Serum sickness is mediated by circulating antigen-antibody immune complexes that deposit in tissues and activate complement. This is the definition of a Type III hypersensitivity reaction.
Step 4: Rule out the others. Anaphylaxis is Type I, occurring within minutes with bronchospasm and hypotension, not a delayed rash. Kawasaki disease requires prolonged fever with mucocutaneous and conjunctival changes, not a drug trigger. Infectious mononucleosis is an EBV infection; its rash typically follows ampicillin or amoxicillin, not cefaclor, and it is not the underlying immune mechanism asked here.
Conclusion: The reaction is a Type III (immune complex) hypersensitivity, so the answer is option 2.
Was this answer helpful?
0
0
Top NEET PG Pathology Questions
- Which of the following is true regarding the Mendelian mode of inheritance?
- A child presents with intermittent jaundice and splenomegaly. There is a history of similar complaints in the elder brother. Peripheral smear shows the following finding. How will you investigate this condition?
- An African child is found to have a mass in the jaw. A biopsy of the mass was done, and it appears as shown in the image below. The child also had a translocation of t(8;14). What is the probable diagnosis?
- A child presented to the hospital with cola-colored urine, hypertension, and puffiness of eyes. Laboratory investigations were done, and creatinine was 2.5 mg/dL. Treatment was started, and despite treatment, the patient did not improve for the next 3 weeks. The creatinine value increased to 4.5 mg/dL. Which among the following electron microscopic findings will be seen in this patient ?
- A patient was transfused 4 units of blood 2 hours ago, and now she complains of chest discomfort. X-ray shows bilateral fissural thickening. Which of the following is the most probable cause ?
View More Questions
Top NEET PG Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions