Challenges in the Diagnosis of Extrapulmonary Tuberculosis and Comparison of Diagnostic Methods

Öz

Objective: Diagnosing extrapulmonary tuberculosis (EPTB) is difficult because of its paucibacillary nature and the need for invasive sampling. This study evaluated the diagnostic performance and inter-test agreement of commonly used methods and identified demographic and clinical features that may assist diagnosis. Methods: This retrospective cohort study was conducted at a tertiary care hospital (2018–2025). EPTB was defined as at least one positive result from acid-fast bacilli (AFB) smear microscopy, polymerase chain reaction (PCR), solid or automated liquid cultures. Demographics, comorbidities, symptoms, laboratory results, histopathological and radiological findings were obtained from medical records. The positivity proportions were calculated, and agreement was assessed using the kappa coefficient. Results: 46 adult patients with EPTB were included. The mean age was 51.6 ± 20.1 years, with female predominance (67.4%). The most frequent sites were the lymph nodes (32.6%), genitourinary tract (21.7%), and musculoskeletal system (21.7%). The highest positivity was observed with automated liquid culture (76.1%), followed by solid culture (71.7%) and PCR (59.5%); AFB smears had the lowest rate (19.6%). Granulomatous inflammation was detected in 63.2% of patients who underwent pathological examination and caseous necrosis in 36.8%. There was slight agreement between AFB smear microscopy, culture, and histopathology. PCR results showed poor agreement with solid and automated liquid cultures, including negative kappa values. Radiological examinations revealed pathological findings in 88.2% of patients, predominantly lymphadenopathy. Conclusion: Clinical and laboratory diagnosis of EPTB remains challenging. These findings support a multimodal strategy that integrates microbiological, molecular, histopathological, and radiological methods to improve diagnostic accuracy.

Anahtar Kelimeler

• Extrapulmonary tuberculosis
• Mycobacterium tuberculosis
• Polymerase Chain Reaction
• Microbiological Techniques
• Biopsy

Ekstrapulmoner tüberküloz tanısında farklı yöntemlerin karşılaştırılması ve tanısal güçlükler

Öz

Amaç: Ekstrapulmoner tüberküloz (EPTB) tanısı düşük basil yükü ve invaziv örnekleme gereksinimi nedeniyle güçtür. Bu çalışma, tanıda kullanılan yöntemlerin tanısal performansını ve aralarındaki uyumu değerlendirmeyi amaçlamıştır. Ayrıca, tanıda yardımcı olabilecek demografik özelliklerle, semptom ve bulguları tanımlamayı hedeflemiştir. Yöntem: Bu retrospektif kohort çalışma, 2018–2025 yılları arasında bir üçüncü basamak üniversite hastanesinde yürütülmüştür. EPTB, asidorezistan basil (AFB) yayma mikroskopisi, polimeraz zincir reaksiyonu (PCR), katı kültür veya otomatize sıvı kültür yöntemlerinden en az birinde pozitiflik saptanmasıyla tanımlanmıştır. Demografik özellikler, komorbiditeler, semptomlar, laboratuvar sonuçları ile histopatolojik ve radyolojik bulgular, elektronik sağlık kayıtlarından retrospektif olarak toplanmıştır. Pozitiflik oranları hesaplanmış ve yöntemler arası uyum kappa katsayısı ile değerlendirilmiştir. Bulgular: Toplam 46 yetişkin EPTB hastası çalışmaya dahil edilmiştir. Ortalama yaş 51,6 ± 20,1 yıl olup kadınlar %67,4 ile çoğunluğu oluşturmuştur. En sık tutulum bölgeleri lenf nodları (%32,6), genitoüriner sistem (%21,7) ve kas-iskelet sistemi (%21,7) olarak saptanmıştır. Tanı testlerinde, en yüksek pozitiflik oranı otomatize sıvı kültürde (%76,1) izlenmiş; bunu katı kültür (%71,7) ve PCR (%59,5) takip etmiştir. AFB yayma mikroskopisinde oran en düşük düzeyde (%19,6) bulunmuştur. Patolojik incelemelerin %63,2’sinde granülomatöz inflamasyon, %36,8’inde kazeöz nekroz tespit edilmiştir. AFB yayması, kültür ve histopatoloji arasındaki uyum düşük kalmıştır. PCR ile katı ve otomatize sıvı kültürler arasında, negatif kappa değerlerine varan düzeyde uyumsuzluk gözlenmiştir. Radyolojik incelemelerde hastaların %88,2’sinde patolojik bulgular raporlanmış ve en sık lenfadenopati izlenmiştir. Sonuç: EPTB’nin klinik ve laboratuvar tanısı günümüzde de zorluklarını sürdürmektedir. Bulgularımız, tanısal doğruluğu artırmak amacıyla mikrobiyolojik, moleküler, histopatolojik ve radyolojik yöntemleri uygun biçimde birleştiren çok yönlü bir yaklaşıma ihtiyaç olduğunu desteklemektedir.

Anahtar Kelimeler

• Ekstrapulmoner tüberküloz
• Mycobacterium tuberculosis
• Polimeraz zincir reaksiyonu
• Mikrobiyolojik teknikler
• Biyopsi

Kaynakça

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