Percutaneous 17/18-gauge Coaxial Ct Guided Core Needle Biopsies of Lung Nodules and Masses at Kenyatta National Hospital: Diagnostic Yield, Complication Rates and Radiological Pattern of Histologically Proven Primary Lung Cancer Histological Subtypes

Abstract

Percutaneous 17/18-gauge coaxial CT guided core needle biopsies of lung nodules and masses at Kenyatta National Hospital: diagnostic yield, complication rates and radiological pattern of histologically proven primary lung cancer histological subtypes. Background: Percutaneous CT guided transthoracic core needle biopsy has become the procedure of choice for the diagnosis of pulmonary lesions [1-4]. This method is effective, safe and minimally invasive thereby providing a real alternative to more invasive surgical procedures like diagnostic thoracotomy [1, 4-6]. Co-axial biopsy needle system is becoming increasingly used as a diagnostic technique in the diagnosis of focal pulmonary pathology. The objective of this study was to determine the diagnostic yield and complication rates of percutaneous 17/18-gauge coaxial CT guided core needle biopsies of lung nodules and masses as seen at a tertiary national referral center. Radiological pattern of the histologically proven bronchogenic carcinoma was also described. Materials and Methods A total of 51 patients with demonstrable lung nodules and masses at imaging were prospectively referred for CT guided biopsy. Pre biopsy CT chest was carried out to confirm the location of the lesion and map out entry site. A 17 gauge coaxial needle was then inserted into the lesion, adjusted and optimal position of the tip confirmed with CT. An 18 gauge trucore biopsy needle was subsequently inserted through the guiding coaxial needle and at least three trucore biopsies obtained for histology. Radiological description of the histologically proven lung cancer was done after histopathological confirmation. Results Forty nine (96.1%) biopsies yielded adequate specimens for histopathological diagnosis. Two specimens were non diagnostic. There were 36(73.5%) malignant lesions and 13(26.5%) benign lesions. Primary lung cancer can accounted for 69.4% while metastatic deposits constituted 4.1% of the cases. Among the primary lung cancers, 32(94.1%) cases were of the NSCLC type and 2(5.9%) cases were of small cell carcinoma type. Squamous cell carcinoma was the most prevalent histological subtype involving 24(70.6) cases followed by adenocarcinoma 8(23.5%). Small cell carcinoma was seen in 2(5.9%). There were no cases of

large cell carcinoma. Of the total number of patients with primary lung cancer, 27 (70.4%) were males and 7(20.6%) were females. More than half (58.8%) of primary lung cancers in the study presented as solid tumours while the rest had a mixture of both solid and ground glass CT attenuation. There were no tumours that presented with pure ground glass attenuation. Squamous cell carcinoma presented most commonly as a central speculated mass while adenocarcinoma presented mainly as a large well outlined homogenous mass with peripheral extension. Cavitation within the primary lung cancers was rare and only seen in squamous cell carcinoma and adenocarcinoma. Calcification was commonest in squamous cell histological subtype. Spiculated mass lesion of either peripheral or central location was the commonest radiological pattern seen in the primary lung cancers. A total of 15 complications occurred in 51 lung biopsies done, 9 (17.6%) being cases of post biopsy pneumothorax and 6(11.8%) being cases of minor lung parenchymal haemorrhage. Only two patients (3.9%) had a pneumothorax of more than 3cm requiring chest tube drainage. Conclusion Percutaneous 17/18 gauge coaxial CT guided core needle biopsies of lung lesions has a high diagnostic yield with low complication rates and is recommended for routine biopsies of lung lesions. Squamous cell carcinoma was the commonest histological subtype presenting most commonly as a central speculated mass.