A 28-year-old woman presents to the ENT clinic with a 4-day history of severe sore throat, dysphagia, and fever (38.5°C). On examination, she has bilateral tonsillar enlargement with yellowish exudate, cervical lymphadenopathy, and mild trismus. Throat culture grows Group A Streptococcus. She is started on oral penicillin V. On day 6 of illness, she develops severe unilateral throat pain, difficulty swallowing saliva, and a muffled voice. Intraoral examination reveals bulging of the soft palate on the left side with displacement of the tonsil medially. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Peritonsillar Abscess ### Key Clinical Features **Key Point:** Peritonsillar abscess (PTA) is a localized collection of pus in the space between the tonsillar capsule and the superior pharyngeal constrictor muscle, typically occurring 4–7 days after acute tonsillitis onset. This patient presents with the classic progression: - Initial acute tonsillitis (bilateral exudate, fever, GAS culture) - Worsening symptoms despite appropriate antibiotic therapy (penicillin V) - Unilateral severe pain with dysphagia and odynophagia - Muffled voice ("hot potato voice") — pathognomonic sign - Intraoral bulging of soft palate with medial displacement of tonsil - Mild trismus (limited mouth opening) ### Pathophysiology 1. Acute bacterial tonsillitis (usually GAS) 2. Spread of infection beyond tonsillar capsule 3. Pus accumulation in peritonsillar space 4. Local tissue edema and abscess formation ### Diagnostic Findings | Feature | Peritonsillar Abscess | Retropharyngeal Abscess | Epiglottitis | |---------|----------------------|------------------------|---------------| | **Onset** | 4–7 days after tonsillitis | 3–5 days after pharyngitis | Acute (hours) | | **Unilateral bulging** | Yes (soft palate) | No (posterior pharyngeal wall) | No | | **Medial tonsil displacement** | Yes (characteristic) | No | No | | **Voice quality** | "Hot potato voice" | Muffled but different quality | Stridor, drooling | | **Trismus** | Mild to moderate | Severe | Minimal | | **Neck stiffness** | No | Yes (posterior neck) | No | **High-Yield:** The combination of unilateral soft palate bulging + medial tonsil displacement + "hot potato voice" is pathognomonic for peritonsillar abscess. ### Management 1. **Imaging:** CT neck with IV contrast (if diagnosis unclear) or ultrasound 2. **Antibiotic escalation:** Switch to broader spectrum (amoxicillin-clavulanate or clindamycin) if not already done 3. **Drainage:** Needle aspiration or incision and drainage (I&D) 4. **Follow-up:** Consider tonsillectomy after acute phase resolves (elective, 4–6 weeks later) to prevent recurrence **Clinical Pearl:** "Hot potato voice" occurs because the abscess prevents normal pharyngeal movement, causing the patient to speak as if holding a hot potato in the mouth. **Warning:** Do NOT confuse peritonsillar abscess with retropharyngeal abscess — the latter presents with posterior pharyngeal wall bulging, severe neck stiffness, and neck rigidity, not soft palate bulging. [cite:Robbins & Cotran 10e Ch 16; Harrison 21e Ch 309]