RESUMO
Coexistence of Mycobacterium xenopi with lung cancer has been reported. However, lung cancer originating within a pre-existing cavity caused by M. xenopi has not. A 55-y-old woman with a history of smoking presented with complaints of chronic dry cough, night sweats, and weight loss for several months. Computed tomography (CT) scanning revealed a 3.5-cm irregular thick-walled cavity in the right lung apex. Cultures obtained from a CT-guided biopsy grew M. xenopi. The patient received standard treatment, and her clinical symptoms improved, and the radiographic lesion stabilized. However, 2 y later, a repeat chest x-ray showed the original right upper lobe cavity with an interval development of a mass adjoining the cavity. A CT-guided needle biopsy of the new mass demonstrated squamous cell carcinoma. Whenever there is a change in the radiological appearance of a cavity, a repeat biopsy should be performed to exclude lung cancer.
Assuntos
Carcinoma de Células Escamosas/etiologia , Neoplasias Pulmonares/etiologia , Pulmão/microbiologia , Infecções por Mycobacterium não Tuberculosas/complicações , Mycobacterium xenopi/isolamento & purificação , Broncoscopia , Carcinoma de Células Escamosas/diagnóstico , Diagnóstico Diferencial , Feminino , Humanos , Biópsia Guiada por Imagem , Pulmão/patologia , Neoplasias Pulmonares/diagnóstico , Pessoa de Meia-Idade , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Infecções por Mycobacterium não Tuberculosas/microbiologia , Tomografia Computadorizada por Raios XRESUMO
Students often have difficulty understanding the relationship of O(2) consumption, CO(2) production, cardiac output, and distribution of ventilation-perfusion ratios in the lung to the final arterial blood gas composition. To overcome this difficulty, I have developed an interactive computer simulation of pulmonary gas exchange that is web based and allows the student to vary multiple factors simultaneously and observe the final effect on the arterial blood gas composition (available at www.siumed.edu/medicine/pulm/vqmodeling.htm). In this article, the underlying mathematics of the computer model is presented, as is the teaching strategy. The simulation is applied to a typical clinical case drawn from the intensive care unit to demonstrate the interdependence of the above factors as well as the less-appreciated importance of the Bohr and Haldane effects in clinical pulmonary medicine. The use of a computer to vary the many interacting factors involved in the arterial blood gas composition appeals to today's students and demonstrates the importance of basic physiology to the actual practice of medicine.
