What is the likely diagnosis for a female patient in her early 60s presenting with a sore throat, afebrile status, negative streptococcal (strep) test, minor swelling sensation under the tongue, and a minor nonproductive cough?

Differential Diagnosis for Sore Throat with Negative Strep Test

Most Likely Diagnosis: Viral Pharyngitis

This patient most likely has viral pharyngitis, given the afebrile presentation, negative strep test, presence of cough, and absence of typical bacterial features such as fever, tonsillar exudates, or tender cervical lymphadenopathy. 1, 2

The clinical presentation strongly supports a viral etiology because:

• Presence of cough is a key distinguishing feature that points away from bacterial causes and toward viral infection 1
• Absence of fever makes Group A Streptococcus highly unlikely, as bacterial pharyngitis typically presents with fever >100.4°F 3
• Negative strep testing effectively rules out the most important bacterial pathogen requiring treatment 2

Comprehensive Differential Diagnosis

Most Common Viral Causes (in order of likelihood):

• Rhinovirus - the most frequent cause of acute pharyngitis 2
• Coronavirus - commonly causes pharyngitis with mild respiratory symptoms 1, 2
• Adenovirus - frequently presents without systemic symptoms 2
• Parainfluenza virus, Respiratory syncytial virus, Influenza virus 1, 2
• Epstein-Barr virus, Enteroviruses, Herpes simplex virus - less common in this age group 1, 2

Less Likely Bacterial Causes (given negative testing):

• Groups C and G β-hemolytic streptococci - can cause pharyngitis similar to GAS but not associated with rheumatic fever 2
• Mycoplasma pneumoniae or Chlamydia pneumoniae - atypical bacteria that can cause pharyngitis with cough 2
• Fusobacterium necrophorum - important to consider in severe cases, though this patient lacks severity markers 1, 4

Special Consideration for Sublingual Swelling:

The minor swelling sensation under the tongue warrants specific attention and raises additional diagnostic possibilities:

• Sublingual salivary gland inflammation (sialadenitis) - can occur with viral infections affecting salivary glands
• Reactive lymphoid tissue - minor lymphoid hyperplasia from viral pharyngitis
• Allergic reaction - though less likely given the temporal association with sore throat
• Candidiasis (thrush) - particularly if the patient has risk factors like recent antibiotics, inhaled corticosteroids, or immunosuppression 5

Critical Clinical Caveat About Testing

In adults with negative rapid strep testing, backup throat culture is generally NOT needed because the specificity of rapid antigen detection tests is ≥95%, making false positives rare. 2 This differs from pediatric populations where confirmation is recommended. 6

Recommended Management Approach

Immediate Management:

• Do NOT prescribe antibiotics - up to 70% of sore throat patients inappropriately receive antibiotics when only 20-30% actually have bacterial infection 2, 6
• Provide symptomatic relief with NSAIDs (ibuprofen or naproxen) or acetaminophen for pain control 2, 7
• Recommend throat lozenges for comfort 2
• Reassure the patient that viral pharyngitis typically resolves in less than 1 week 2

Specific Evaluation for Sublingual Swelling:

• Examine the floor of mouth carefully for evidence of candidiasis (white plaques), salivary duct obstruction, or abscess formation
• Ask about risk factors for candidiasis: recent antibiotic use, inhaled corticosteroid use, diabetes, immunosuppression 5
• Consider KOH preparation if oral candidiasis is suspected based on examination 5

Red Flags Requiring Urgent Reassessment:

• Development of fever, difficulty swallowing, or systemic symptoms 2
• Worsening symptoms after 3-5 days instead of improvement 2
• Respiratory distress or stridor 2
• Severe unilateral throat pain with trismus - suggests peritonsillar abscess 1
• Neck swelling, tenderness, or painful swollen neck with pulmonary symptoms - raises concern for Lemierre syndrome 1, 4
• Inability to swallow secretions or drooling 7

Key Pitfalls to Avoid

Do not treat based on symptom severity alone without laboratory confirmation - this leads to unnecessary antibiotic use, adverse effects (rash, diarrhea, anaphylaxis), and promotes antimicrobial resistance. 2, 6

Do not assume the sublingual swelling is insignificant - while likely reactive, it requires direct visualization to exclude candidiasis, abscess formation, or other pathology that might require specific treatment. 5

Do not miss non-infectious causes in patients with atypical presentations or risk factors - consider hematologic disorders, vasculitis, or medication reactions if the clinical picture doesn't fit typical viral pharyngitis. 5

Remain vigilant for Lemierre syndrome in patients with severe pharyngitis who develop neck pain or swelling, even with negative strep testing, as this is a rare but life-threatening condition requiring urgent diagnosis and treatment. 1, 4