An Unusual Case of Lung Cancer Originating From Cavitary M. xenopi Infection

Abstract

INTRODUCTION: Cavitary lung lesions are radiologically defined as air containing lesions with a wall within an area of a surrounding infiltrate, mass or nodule. Cavitary M.Xenopi infection is more commonly reported in Canada, the United Kingdom and Europe. Cavitation is present in up to 20% lung cancers and typically occurs in Squamous cell carcinoma. However, Lung cancer originating from preexisting cavity caused by Mycobacterium is rare. CASE PRESENTATION: A 55 year old homeless female with h/o alcohol abuse and a 30 pack year h/o cigarette smoking presented to ED c/o progressive SOB on exertion for 1 month and a chronic dry cough for many years. She also c/o occasional night sweats and weight loss. Physical exam was unremarkable. CXR showed 4.2 cm cavitary lesion in right apex with Hyperinflation. CT Chest showed 3.5 cm irregular thick walled cavitary lesion in the apex of the right lung with emphysema. Quantiferon GOLD test, sputum AFB smear and culture, fungal serology and HIV serology were negative. CT guided needle biopsy revealed chronic necrotizing granulomatous inflammation with Acid fast bacilli on Ziehl-Neelsen stain. AFB culture from biopsy grew confirmed M.Xenopi. She was started on treatment with azithromycin, ethambutol and rifampin followed by improvement in her clinical symptoms. CXR at the end 18 months of treatment showed the RUL cavitary lesion was unchanged. A repeat CXR after 2 years showed persistent right upper lobe cavitary lesion with the interval development of a linear density inferolateral to the cavitary lesion. Repeat CT guided needle Biopsy showed poorly differentiated squamous cell carcinoma. DISCUSSION: Cavitary lung lesions occur in a wide spectrum of diseases. Multiple cases of co-existing infection and malignancy have been reported. However, it is quite uncommon to have lung cancer developing from preexisting cavity caused by infectious etiology such as M.Xenopi. Whenever there is change in character of cavity on follow-up imaging, possibility of lung cancer should be kept in mind and should be confirmed by biopsy even though previous biopsy suggestive of Infectious etiology of cavitary lesion.Chronic Inflammation from infection leading to scarring along with effect of smoking might be leading to development of lung cancer in such cases. CONCLUSIONS: Lung cancer can arise from chronic cavitary lesion of infectious etiology such as M.Xenopi. Whenever there is change in radiological appearance of a cavity, repeat biopsy should be performed to rule out lung cancer.