Clinical Meetings at RH Year 2008

2008 Clinical Meeting QMH - Let every eye negotiate for itself

Drs Macy MS LUI & Matthew KY WONG; Department of Medicine, Queen Mary Hospital

Case 1
A 56-year-old Chinese lady presented with right loin pain in April 2007. She was assessed by urologist with intravenous urogram showing right ureteric stone and obstruction. She received extracorporeal shock wave lithotripsy. A CT abdomen was performed subsequently to confirm stone clearance which incidentally found a 2cm nodule at right lung.



Her renal function was impaired with creatinine 190 mmol/l and urea 11 umol/l. Adjusted calcium level was 3.04 mmol/l. 24-hour urine for calcium was elevated. Parathyroid hormone was suppressed. Endobronchial ultrasound (EBUS) with transbronchial needle aspiration (TBNA) of the mediastinal lymph nodes yielded non-caseating granulomatous inflammation. The differential diagnoses included tuberculosis, malignancy with lymph node metastases and sarcoidosis. A conventional bronchoscopy with transbronchial biopsy targeted at the lung nodule showed non-specific changes. Bronchoalveolar lavage at right middle lobe was negative for fungal culture, polymerace chain reaction for tuberculosis and acid fast bacilli (AFB) culture. Fine needle aspiration of the lung nodule under CT guidance yielded atypical cells. She then proceeded to open biopsy of right middle lobe nodule and mediatinal lymph node sampling via video-assisted thoracosopic surgery. The histology revealed non-caseating granuloma and stains for AFB and fungus were negative. The ultimate diagnosis was sarcoidosis. She was treated with prednisolone with good response.

Solitary pulmonary nodule is an atypical feature for sarcoidosis and histological diagnosis is warranted. The use of EBUS with TBNA for investigation of suspected sarcoidosis was evaluated in 65 subjects from a Japanese and a German centre.1 The diagnostic yield of EBUS-TBNA for stage I/II sarcoidosis reached 92%, which is superior to blind TBNA (42-76%). No complications were noted and most importantly, EBUS provides access to the hilar LNs, which are the blind spot of mediastinoscopy.

Case 2
A 61-year-old chronic heavy smoker was incidentally found to have a right lower zone nodule on chest X ray. He had severe chronic obstructive pulmonary disease (COPD) and his FEV1 was 1.32L (38% predicted). A whole body FDG positron emission tomograph and computed tomograph showed hyper-metabolic nodule (2.1x1.6x0.8cm SUV 5.8) at anterior basal segment of right lower lobe and hypermetabolic bilateral hilar lymphadenopathy (right hilar lymph nodes was 1.5x2.6cm and SUV 11.5, left hilar lymph node was 1.0x1.4cm and SUV 8.6). EBUS with TBNA of right hilar lymph node was performed. While the EBUS was approaching the left hilum for hilar lymph node sampling, an endobronchial mass was discovered unexpectedly.

The right hilar lymph node showed small cell lung carcinoma staining positive for CD 56, thyroid transcription factor-1 (TTF-1) and weakly positive for p63. The endobronchial biopsy from left lower lobe tumour stained positive for p63 and negative for CD 56 and TTF-1, compatible with squamous cell carcinoma. This case illustrate the potential pitfall of missing synchronous lung tumour if the diagnosis is based either on sampling from intrathoracic lymph node or from endobronchial lesion alone. It also demonstrates that adequate tissue can be obtained using EBUS for immunohistochemical staining and differentiation of various cell types of tumour. This case was reported on the journal Lung Cancer.2

Case 3
A 75-year-old chronic smoker with history of pulmonary tuberculosis had regular CXR surveillance by chest clinic. A new left upper zone mass was noted on recent CXR. The PET-CT showed hypermetabolic right upper lobe nodule (1.6x1.7x1.9 cm and SUV 6.3), hypermetabolic right precarinal and paratracheal lymph nodes, with SUV up to 3.1. Transbronchial biopsy at left upper lobe confirmed squamous cell carcinoma. Based on the PET-CT finding, the tumour was deemed inoperable due to the presence of contralateral lymphadenopathy (N3). EBUS with TBNA of the paratracheal and precarinal lymph nodes was performed which were negative for metastasis. The negative histology was further substantiated by mediastinoscopy. The patient finally underwent left upper lobectomy with mediastinal lymph node dissection. The pathological staging was T1N0M0, consistent with EBUS finding. This case demonstrates the occurrence of false positivity of PET-CT for lymph node staging. The positive predictive value of PET scan was reported to be about 46%.3 The importance of obtaining a histological confirmation of lymph node metastasis before declaration of inoperability is highlighted. The availability of EBUS and TBNA of lymph nodes denotes a major breakthrough in nodal staging of lung cancer. It provides access to hilar lymph nodes, yields adequate tissue for histology and immunohistochemical staining while the risks of general anaesthesia are avoided.

Reference:

1. Wong KYM, Yasufuku K., Nakajima T. et al. Endobronchial ultrasound: new insight for the diagnosis of sarcoidosis. Eur Resp J 2007; 29: 1182-86.
2. Wong KYM, Wong MP, Lam CL, et al. Endobronchial ultrasound for diagnosis of synchronous primary lung cancers. Lung Cancer 2008 Jun 26.
3. Yasufuku K, Nakajima T, Motoori K, et al. Comparison of endobronchial ultrasound, positron emission tomography, and CT for lymph node staging of lung cancer. Chest. 2006 Sep; 130(3):710-8