What are the differential diagnoses for unilateral ulcerated throat pain?

Differential Diagnosis for Unilateral Ulcerated Throat Pain

The differential diagnosis for unilateral ulcerated throat pain must prioritize life-threatening and treatable conditions including malignancy, infectious causes (particularly syphilis and tuberculosis), subacute thyroiditis, and autoimmune/inflammatory conditions, with systematic evaluation guided by duration, patient risk factors, and response to initial treatment.

Infectious Etiologies

Bacterial Infections

• Primary syphilis can present as unilateral tonsillitis with ulceration and exudate, particularly in patients with history of unprotected oral intercourse 1

  • Gram staining of pus may reveal gram-negative corkscrew-like spirochaetes 1
  • Rapid streptococcal testing will be negative, necessitating specific syphilis serology 1

• Tuberculosis presents with stellate ulcers with undermined edges and clear boundaries 2

  • Granulomatous inflammation with Langhans-type giant cells on biopsy 2
  • Ziehl-Nielsen staining demonstrates acid-fast bacilli 2

• Anaerobic infections including Prevotella species (especially Prevotella disiens) can cause necrotizing unilateral tonsillitis 3

  • Transmission occurs through poor hygiene and sexual contact 3

• Angina Plaut-Vincent (fusospirochetosis) remains a classic cause of unilateral necrotizing tonsillitis 3

Fungal Infections

• Invasive fungal infection should be suspected in patients with hyperglycemia or immunosuppression 2
  • Elevated 1-3-β-D-glucan and galactomannan levels support diagnosis 2

Inflammatory and Autoimmune Conditions

Thyroid-Related

• Subacute thyroiditis frequently presents as unilateral pharyngalgia and is commonly misdiagnosed as pharyngitis or tonsillitis in 43.7% of cases 4
  • Key diagnostic features include thyroid tenderness on palpation, abnormal thyroid function tests, elevated ESR, and decreased radioactive iodine uptake 4
  • Pain duration ranges from 7 days to 3 months, with left-sided predominance (59% left vs 41% right) 4

Other Inflammatory Causes

• Laryngeal contact ulcer presents with globus sensation, throat clearing, and voice changes 5

  • Histology shows mucosal ulceration with fibrinoid necrosis and granulation tissue 5

• Autoimmune bullous diseases including pemphigus and pemphigoid require evaluation with serum antibodies (Dsg1, Dsg3, BP180, BP230) 2

Neoplastic Causes

• Tonsillar carcinoma must be excluded in any unilateral ulcerated lesion 3

  • Neoplastic ulcerated lesions notoriously mimic benign conditions in the oral cavity 6
  • Biopsy is essential for lesions persisting >2 weeks or not responding to 1-2 weeks of treatment 2

• Hematopoietic and lymphoid neoplasms including NK/T-cell lymphoma can present as oral ulceration 2

  • Requires immunohistochemical assay and T-cell receptor immunophenotyping 2

Traumatic Causes

• Mechanical trauma from sharp edges of teeth, dental work, or foreign bodies 2

  • Diagnosis based on location and shape corresponding to stimulating factor 2

• Chemical or thermal burns from caustic substances or hot foods 2

Systemic Disease Associations

• Inflammatory bowel disease (particularly Crohn's disease) can manifest with oral ulceration preceding or accompanying intestinal symptoms 2

• Hematologic disorders including leukemia and severe neutropenia present with necrotic oral ulcers 2

  • Full blood count showing decreased neutrophils warrants bone marrow biopsy 2

Critical Diagnostic Approach

Initial Evaluation

• Thyroid palpation is mandatory in all patients with unilateral pharyngalgia to avoid missing subacute thyroiditis 4

• Sexual history is essential, as sexually transmitted infections are frequently overlooked in adult tonsillitis 1

Laboratory Testing Before Biopsy

For ulcers >2 weeks duration or not responding to treatment 2:

• Full blood count (rule out hematologic malignancy) 2
• HIV antibody and syphilis serology 2
• Fasting blood glucose (fungal infection risk) 2
• ESR/CRP (inflammatory conditions) 4
• Thyroid function tests if thyroid tenderness present 4

Biopsy Indications

• Lesions persisting >2 weeks 2
• Lack of response to 1-2 weeks of appropriate treatment 2
• Multiple sites with different morphology require multiple biopsies 2

Common Pitfalls

• Misdiagnosis as simple pharyngitis/tonsillitis occurs in nearly half of subacute thyroiditis cases 4
• Negative rapid strep test does not exclude serious pathology including syphilis 1
• Failure to obtain sexual history leads to missed sexually transmitted infections 1, 3
• Inadequate biopsy technique or specimen handling for anaerobic cultures 3
• Assuming benign etiology without biopsy in persistent cases risks missing malignancy 6