A 17 years old female presents with sore throat, lymphadenopathy and positive heterophile antibodies test. Diagnosis is ?
**Core Concept**
The patient's presentation of sore throat, lymphadenopathy, and positive heterophile antibodies test is suggestive of an infectious mononucleosis, a condition caused by the Epstein-Barr virus (EBV) that affects lymphocytes and leads to a severe immune response.
**Why the Correct Answer is Right**
The heterophile antibodies test, also known as the Monospot test, detects the presence of antibodies against the EBV, which are also reactive against the sheep red blood cells. This is a characteristic feature of infectious mononucleosis. The sore throat and lymphadenopathy are due to the EBV's effect on the lymphocytes, causing a lymphocytosis and activation of the immune system. The EBV infects the B lymphocytes, leading to their proliferation and activation, resulting in the clinical symptoms.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not match the clinical presentation of sore throat, lymphadenopathy, and positive heterophile antibodies test, which is characteristic of infectious mononucleosis.
* **Option B:** This option is incorrect because it does not account for the positive heterophile antibodies test, which is a diagnostic hallmark of infectious mononucleosis.
* **Option C:** This option is incorrect because it does not match the age and sex of the patient, as streptococcal pharyngitis is more common in children and young adults.
* **Option D:** This option is incorrect because it does not account for the positive heterophile antibodies test and the lymphadenopathy, which are characteristic of infectious mononucleosis.
**Clinical Pearl / High-Yield Fact**
Infectious mononucleosis can be a significant cause of morbidity in adolescents and young adults, and the diagnosis should be considered in any patient with sore throat, lymphadenopathy, and positive heterophile antibodies test.
**Correct Answer:** C.