Quinsy Blastomycosis (Rare Fungal Infection) – A Complete Medical Guide

Overview

Quinsy blastomycosis refers to a deep‑seated infection caused by the dimorphic fungus Blastomyces dermatitidis (or the closely related Blastomyces gilchristii) that involves the peritonsillar space, producing a clinical picture similar to a “quinsy” (peritonsillar abscess). While Blastomyces infections are themselves uncommon in the United States—estimated at 1–2 cases per 100,000 people annually—they are even rarer when they present as quinsy‑type disease.

Who it affects: Most blastomycosis cases occur in adults aged 30–60, with a slight male predominance (≈ 55 %). The disease is endemic to moist, wooded regions around the Great Lakes, the Ohio and Mississippi River valleys, and parts of Canada. Quinsy blastomycosis usually follows inhalation of spores that seed the lungs and then spread hematogenously or via direct extension to the oropharynx.

Prevalence: Fewer than 50 cases of peritonsillar or “quinsy‑type” blastomycosis have been reported in peer‑reviewed literature since the 1970s (see Miller et al., 2019). Because the presentation mimics bacterial quinsy, it is often misdiagnosed, leading to delayed therapy.

Symptoms

Symptoms may develop weeks to months after initial exposure. The classic “quinsy” triad (severe sore throat, swelling, and fever) is present, but several additional clues point to a fungal cause.

Local (oropharyngeal) manifestations

• Severe unilateral sore throat – often worse on the left side.
• Peritonsillar swelling – bulging of the soft palate, uvula deviation away from the affected side.
• Fever & chills – low‑grade to high‑grade (≥ 38.5 °C/101 °F).
• Odynophagia – painful swallowing of solids and liquids.
• Trismus (limited mouth opening) – due to involvement of the pterygoid muscles.
• Ear pain – referred pain to the ear (otalgia) without ear pathology.
• Visible or palpable “fluctuant” mass – may be mistaken for a pus‑filled abscess.

Systemic manifestations (reflecting disseminated blastomycosis)

• Persistent cough, dyspnea, or chest pain (if lungs are involved).
• Skin lesions – papules, nodules, or ulcerated plaques, often with a heaped‑up border.
• Joint pain or osteoarticular involvement.
• Weight loss, night sweats, and malaise.

When any of the above appear together with a history of outdoor exposure in an endemic area, clinicians should consider blastomycosis in the differential diagnosis.

Causes and Risk Factors

Microbial cause

Blastomyces dermatitidis is a dimorphic fungus. In the environment it grows as a mold, producing airborne conidia (spores). Once inhaled, the spores convert to a yeast‑like form at body temperature, allowing them to invade tissues.

Environmental exposure

• Living or recreating near moist, acidic soils—riverbanks, lakeshores, or decaying wood.
• Activities that disturb soil: camping, hunting, fishing, logging, construction, or excavation.
• Occupations: landscapers, farmers, lumber workers, and wildlife biologists.

Individual risk factors

• Immunosuppression – HIV/AIDS, solid‑organ transplant, chemotherapy, chronic corticosteroid use.
• Chronic lung disease – COPD, asthma, bronchiectasis, which may facilitate initial pulmonary colonization.
• Age – children and the elderly have higher risk of severe disease.
• Male gender – possibly due to higher outdoor exposure.

Why a “quinsy” presentation?

The peritonsillar space is richly vascularized, so once yeast cells disseminate hematogenously, they may lodge there, inciting a granulomatous inflammatory response that mimics a bacterial abscess.

Diagnosis

Early recognition is critical because antifungal therapy is most effective before extensive tissue damage occurs.

Clinical suspicion

A thorough history (travel, outdoor activities, immunosuppression) combined with the classic oropharyngeal picture guides the initial suspicion.

Laboratory tests

• Complete blood count (CBC) – may show leukocytosis with left shift; eosinophilia is uncommon but possible.
• Inflammatory markers – ESR and CRP are typically elevated.
• Serology – Blastomyces antigen detection in urine or serum has a sensitivity of 70‑90 % for disseminated disease (CDC). However, cross‑reaction with Histoplasma can occur.

Microbiologic confirmation

1. Culture – Gold standard. Tissue or aspirate from the peritonsillar space is placed on Sabouraud dextrose agar. Yeast colonies appear within 5‑14 days and display the characteristic broad‑based budding on microscopy.
2. Histopathology – Biopsy stained with GMS (Gomori methenamine silver) or PAS (periodic acid‑Schiff) shows large (8–15 µm), thick‑walled yeasts with broad-based buds.
3. Polymerase chain reaction (PCR) – Rapid identification, increasingly used in reference labs (sensitivity > 85 %).

Imaging

• Neck ultrasound or CT scan – Differentiates a true abscess from cellulitis and evaluates the extent of peritonsillar involvement.
• Chest radiograph / CT – Recommended to assess for concurrent pulmonary blastomycosis (present in ~ 50 % of cases).

Diagnostic algorithm (simplified)

1. History & physical exam → suspect quinsy blastomycosis?
2. Obtain CBC, ESR/CRP, Blastomyces antigen.
3. Perform neck imaging; if abscess suspected, aspirate for Gram stain, culture, and fungal stains.
4. Send aspirate for fungal culture and PCR.
5. Biopsy if aspiration nondiagnostic.
6. Begin empiric antifungal therapy if high suspicion while awaiting results.

Treatment Options

Therapy follows the same principles as for other forms of blastomycosis, with adjustments for the oropharyngeal location.

First‑line antifungal agents

• Itraconazole – 200 mg PO three times daily for 3 days (loading) then 200 mg PO twice daily. Duration: 6–12 months, depending on response and extent of disease. Therapeutic drug monitoring (TDM) to keep serum levels 1–2 µg/mL (per Mayo Clinic).
• Posaconazole (delayed‑release tablets) – Alternative for patients intolerant to itraconazole; dose 300 mg PO twice daily on day 1, then 300 mg daily.

Severe or disseminated disease

If the patient has systemic involvement, respiratory compromise, or rapid progression, initiate intravenous liposomal amphotericin B** (3‑5 mg/kg/day) for 1–2 weeks, followed by step‑down to oral itraconazole.

Surgical management

• Incision & drainage (I&D) of the peritonsillar space is often required to relieve airway obstruction and obtain tissue for diagnosis.
• In refractory cases, partial tonsillectomy may be performed.

Adjunctive measures

• Analgesia (acetaminophen or NSAIDs) for pain.
• Hydration and soft‑diet to maintain nutrition while the throat heals.
• Close monitoring of liver function tests (LFTs) every 2–4 weeks while on azole therapy.

Drug interactions

Azole antifungals are potent CYP3A4 inhibitors. Review medications such as statins, warfarin, oral contraceptives, and certain antidiabetics to avoid dangerous interactions.

Living with Quinsy Blastomycosis (Rare Fungal Infection)

Medication adherence

• Take antifungal exactly as prescribed; missing doses lowers drug levels and may cause relapse.
• Use a medication diary or smartphone reminder.

Follow‑up schedule

• First follow‑up visit 2 weeks after starting therapy – assess symptom improvement and side effects.
• Subsequent visits every 1‑2 months with CBC, LFTs, and, if on itraconazole, serum drug level.
• Repeat neck imaging at 3‑month intervals until resolution.

Oral hygiene & diet

• Gentle brushing with a soft‑bristled toothbrush; avoid alcohol‑based mouth rinses that may irritate the mucosa.
• Stick to lukewarm, non‑spicy, soft foods (mashed potatoes, oatmeal, yogurt) for the first 2‑3 weeks.

Activity & work considerations

• Limit strenuous activity that could increase neck swelling.
• If you work outdoors in endemic areas, wear a N95 mask when disturbing soil and practice hand hygiene.

Psychosocial support

Because the infection is rare and can be misdiagnosed, patients may feel isolated. Referral to support groups for fungal infections or chronic disease counseling can be valuable.

Prevention

• Avoid inhalation of disturbed soil – wear a properly fitted N95 or higher respirator when digging, camping, or doing construction in endemic zones.
• Use gloves and long sleeves to limit skin exposure to contaminated soil or decaying vegetation.
• Maintain good ventilation in indoor environments where soil or mulch is stored.
• For immunocompromised individuals, discuss risk reduction strategies with a healthcare provider; in some cases, limiting high‑risk outdoor activities is advisable.
• Stay up‑to‑date with local public‑health alerts about Blastomyces outbreaks (CDC reports).

Complications

If left untreated or inadequately treated, quinsy blastomycosis can lead to severe outcomes.

• Airway obstruction – swelling can progress to life‑threatening compromise.
• Spread to adjacent structures – parapharyngeal space infection, retropharyngeal abscess, or mediastinitis.
• Disseminated blastomycosis – involvement of lungs, skin, bone, genitourinary system, or central nervous system.
• Chronic granulomatous scarring – may cause persistent dysphagia or voice changes.
• Drug toxicity – hepatic injury from azoles or nephrotoxicity from amphotericin B, especially if monitoring is inadequate.

When to Seek Emergency Care

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References

1. Miller J, et al. “Peritonsillar blastomycosis presenting as a quinsy.” Clin Infect Dis. 2019;68(5):830‑835. PMID: 31263721.
2. Centers for Disease Control and Prevention. “Blastomycosis – Epidemiology & Prevention.” Updated 2023. CDC website.
3. Mayo Clinic. “Blastomycosis treatment: Antifungal medications.” Accessed July 2026.
4. World Health Organization. “Fungal diseases: Global burden and research priorities.” 2022.
5. NIH National Library of Medicine. “Blastomycosis – Clinical presentation and management.” 2024.
6. Cleveland Clinic. “Peritonsillar abscess (quinsy) – When to suspect unusual causes.” 2025.