A 28-year-old man from rural Maharashtra presents with a 5-day history of severe left-sided neck pain, dysphagia, and fever (38.5°C). On examination, he has trismus, left intraoral swelling pushing the soft palate medially, and a palpable firm mass in the left lateral pharyngeal wall. Neck movements are restricted. Laboratory studies show WBC 14,200/μL with left shift. CT neck with contrast reveals a 4 cm hypodense collection in the left lateral pharyngeal space with rim enhancement. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Lateral Pharyngeal Space Abscess ### Key Clinical Features **Key Point:** The lateral pharyngeal space (parapharyngeal space) is bounded medially by the superior pharyngeal constrictor and laterally by the mandible and styloid process. Infection here presents with characteristic intraoral swelling that displaces the soft palate medially and pharynx medially. ### Distinguishing Features | Feature | Lateral Pharyngeal | Retropharyngeal | Peritonsillar | Submandibular | |---------|-------------------|-----------------|---------------|---------------| | **Intraoral bulge location** | Lateral pharyngeal wall, pushes palate MEDIALLY | Posterior pharyngeal wall, pushes palate FORWARD | Lateral to tonsil, soft palate | Floor of mouth | | **Trismus** | Present | Minimal | Present | Minimal | | **Dysphagia** | Marked | Marked | Moderate | Moderate | | **Neck stiffness** | Minimal | Common (posterior extension risk) | Absent | Absent | | **Common source** | Pharyngitis, dental | Pharyngitis, adenoiditis | Tonsillitis | Dental (lower molars) | | **Imaging: collection location** | Lateral to pharynx, medial to mandible | Posterior to pharynx, anterior to prevertebral fascia | Lateral to tonsil | Submandibular triangle | ### Why This Case Fits Lateral Pharyngeal Space 1. **Intraoral swelling pushing soft palate medially** — pathognomonic for lateral pharyngeal space; retropharyngeal pushes it forward/backward 2. **Palpable firm mass in lateral pharyngeal wall** — direct evidence of lateral location 3. **CT: hypodense collection in lateral pharyngeal space** — imaging confirms diagnosis 4. **Trismus + dysphagia + fever** — classic presentation of deep neck space infection **High-Yield:** Lateral pharyngeal space abscess is a surgical emergency. Risk of rupture into carotid sheath with carotid artery erosion and life-threatening hemorrhage; also risk of mediastinitis if infection tracks downward. ### Management Implications **Clinical Pearl:** Unlike peritonsillar abscess (which may be managed with antibiotics ± needle aspiration), lateral pharyngeal space abscess requires: - Urgent imaging (CT or MRI) - Broad-spectrum IV antibiotics (covering Streptococcus, Staphylococcus, anaerobes) - Surgical drainage via external approach (transcervical) or intraoral approach depending on loculation and anatomy - Airway assessment and possible intubation/tracheostomy **Mnemonic: LPSA** — **L**ateral **P**haryngeal **S**pace **A**bscess: **L**ateral bulge, **P**alate pushed **M**edially, **S**urgical drainage needed, **A**irway at risk. [cite:Cummings Otolaryngology 6e Ch 81]