Oct 27 • Announcement
New station added to pathology-Dermatology
🍄ACTINOMYCOSIS
🩺 Clinical Vignette
A 25-year-old female with Crohn’s disease on steroids presents with a 4 cm ulcer on the face.On incision, you find greenish pus containing yellowish granules.
❓Q1. What is the most likely diagnosis?
Actinomycosis — a chronic granulomatous infection caused by Actinomyces israelii, a gram-positive, anaerobic, filamentous bacterium.
❓Q2. What are the typical features of Actinomycosis?
- Chronic, indolent infection with abscesses, fibrosis, and sinus tracts
- Discharges thick pus with yellow “sulphur granules”
- Mimics malignancy due to firm mass and tissue invasion
❓Q3. Where does this organism normally live?
It is a commensal in:
- Oral cavity
- Gastrointestinal tract
- Female genital tract
❓Q4. What are the risk factors?
- Mucosal trauma (e.g. dental extraction, oral sepsis)
- Steroid use / immunosuppression
- Poor oral hygiene
- IUD use (pelvic actinomycosis)
- GI pathology – appendicitis, diverticulitis
- Aspiration of oral secretions
❓Q5. What is the pathogenesis?
- Mucosal barrier disrupted
- Actinomyces invades deep tissues
- Forms chronic abscess → fibrosis → sinus tracts
- Sulphur granules represent bacterial colonies
❓Q6. What are the common sites of infection?
SiteFeaturesCervicofacial (“Lumpy jaw”)Post-dental infection; firm jaw swelling with discharging sinusesThoracicAspiration from oral cavity → chronic pneumonia or abscessAbdominal / PelvicFollows bowel perforation or IUD; may mimic malignancyCNSSecondary spread causing brain abscessMandibleOsteomyelitis after trauma/dental surgery
❓Q7. Why can Actinomycosis mimic malignancy?
Because it causes a firm, fibrotic, slowly enlarging mass that invades adjacent tissues and forms fistulae.
❓Q8. What are the characteristic findings at surgery?
- Greenish pus with yellow “sulphur granules”
- Dense fibrotic tissue and sinus tracts
- Granules seen in < 50 % of cases
- Culture confirmation needed (slow-growing anaerobe)
❓Q9. How is the diagnosis confirmed?
- Microscopy and culture of pus / aspirate (under anaerobic conditions)
- Histology showing branching filamentous Gram-positive rods
- Differentiate from Nocardia (which is aerobic and weakly acid-fast)
❓Q10. What are the differential diagnoses?
- Nocardia infection
- Tuberculosis
- Chronic osteomyelitis
- Carcinoma (especially in cervicofacial region)
❓Q11. How is it managed?
1. AntibioticsHigh-dose Penicillin G IV 6–12 weeks → oral 3–6 months
2. Allergy alternativeDoxycycline or Erythromycin
3. SurgeryDrain abscesses, excise sinus tracts, remove foreign bodies/IUD
4. MDT careInvolve microbiologist + dental/oral surgeon
❓Q12. What are the possible complications?
- Osteomyelitis (esp. mandible)
- Chronic fibrosis and sinus tracts
- Fistula formation
- Recurrence if treatment incomplete
- Mass effect mimicking cancer
❓Q13. Is it contagious?
❌ No.Actinomycosis is not transmitted person-to-person.
❓Q14. What is the prognosis?
Excellent if treated with prolonged high-dose antibiotics and adequate drainage.Relapses occur if therapy is shortened.
💬 Common Examiner Questions
- How do you differentiate Actinomyces from Nocardia? → Anaerobic & non-acid-fast vs. aerobic & acid-fast.
- Why is prolonged antibiotic therapy required? → Dense fibrosis limits drug penetration; organism grows slowly.
- What does presence of sulphur granules indicate? → Colonies of Actinomyces surrounded by immune debris.
- When would you involve surgery? → Non-resolving abscesses, sinus tracts, IUD-related disease.
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New station added to pathology-Dermatology
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