Pancreatic cancer mimicking lung cancer
Diagnostic confusion in an apparently straight forward case of lung cancer which later turned out to be a probable pancreatic cancer.
85 yr old male was admitted from the emergency with breathlessness and hoarseness of voice 2 weeks duration. He was on treatment for type 2 diabetes. He was also an ex-smoker. O/E he was dyspnoeic. He had no pallor, jaundice, lymphadenopathy, cyanosis or clubbing. He also had mild bilateral pedal edema.
Diagnosis & Treatment :
The initial tests were remarkable for neutrophilic leukocytosis and hyponatremia, massive left sided pleural effusion (chest x-ray & ultrasound of thorax). The patient improved symptomatically with intercostal drainage. Subsequently CECT Thorax, Abdomen and Pelvis revealed a spiculated heterogenously enhancing mass 6.3 x 2.2 x 4.7 cm in upper lobe of left lung, patchy consolidation of left lower lobe, right supraclavicular, right para-tracheal and sub-carinal lymphadenopathy (all subcentimeter),ICD in situ and a cystic lesion in the head of the pancreas measuring 4.8 x 3.1 x 3.5 cm. The pleural fluid revealed malignant cells suggestive of adenocarcinoma. Therefore cell block was made from the pleural fluid for special tests. The course in the hospital was prolonged with patient's condition deteriorating due to atrial fibrillation. He also developed altered sensorium even after correcting the hyponatremia (non-contrast CT Brain revealed hypodensities most likely due to cerebral infarcts) and obstructive urinary symptoms due to prostatic enlargement (with PSA 22. 6 ng/ml). Eventually the patient recovered and we managed to do pleurodesis. We had also started the patient on tablet Gefitinib 250 mg once daily pending the pleural fluid results, taking into account the poor general condition of the patient and diagnosis of lung cancer. The patient was then discharged. However, the special tests from the pleural fluid revealed that the cancer was not primarily from the lung (IHC TTF-1 and Napsin were negative). Further IHC (immunohistochemistry tests were done which suggested that the malignancy is probably of pancrease/GI origin. Tumour markers were also done which showed an elevated CA 19-9 (264.97 U/ml).Further tests, including biopsy/FNAC directly from the lung/ pancreatic mass was not contemplated.
This case represents a not so infrequent diagnostic problem in medicine. The final pathological diagnosis is contrary to what it seemed certain clinically. The clinical features were consistent with a diagnosis of advanced lung carcinoma – a spiculated solitary lung lesion with ipsilateral pleural thickening and effusion. Spiculated lung lesions strongly suggest a primary lung cancer rather than a metastatic lesion. The odd features were cystic pancreatic lesion and a mildly elevated CA 19-9. Radiologically the pancreatic lesion appeared benign and clinically there were no signs or symptoms pertaining to the lesion. CA 19-9 is a tumour marker which is associated with pancreatic, biliary tract and mucinous ovarian cancers. However, it is not specific for the above mentioned cancers and the raised level of CA 19-9 does not confirm diagnosis. The PSA was only marginally elevated suggesting benign prostatic hyperplasia. The patient was started on treatment with tab. Gefitinib, which is used for lung cancer, once the pleural fluid cytology revealed adenocarcinoma. But the pathologist had doubts regarding the primary site of the tumour. Hence immunohistochemistry was done on the pleural fluid cell block study. (Immunohistochemistry are special tests done on the histopathology sample which strongly aid in categorizing cancers, especially lung cancer). To our surprise, the results were strongly against a primary lung cancer (as evidenced by the negative results of TTF-1 and Napsin). Further immunohistochemical tests were done which narrowed the possibilities to a pancreatic or intestinal primary. The patient's poor general condition and cystic characteristic of the pancreatic lesion prevented us from doing further biopsy/aspiration from that site. Though it may seem inappropriate, the treatment with tab. Gefitinib was continued, because the re-assessment with contrast enhanced CT Thorax & CA 19-9 revealed a stable disease and the medicine had very little side-effects. In this era of advanced technology, we heavily rely on different kinds of scans like CT, MRI & PET/CT for diagnosing and treating cancer patients. But in this case the clinical impression and what was revealed in the scan was misleading. Further specialized tests were done on the suspicion of the pathologist. Thus the experience of the doctor does matter in this era of modern technology aided treatment.
Post Treatment :
Repeated re-assessments were done at one and two months of discharge with CT Thorax and CA 19-9 which revealed stable disease.