A 55-year-old woman comes to the office due to a persistent cough, exertional dyspnea, and recent, unintentional weight loss. She has no chronic medical problems and takes no medication regularly. She has never smoked and has no history of exposure to industrial pollutants. She works as an accountant at a large accounting firm. Vital signs are normal. Physical examination reveals decreased breath sounds and dullness to percussion at the left lung base. Imaging studies show an irregular mass in the lower lobe of the left lung and a left pleural effusion. A diagnostic thoracocentesis is performed and the aspirated fluid is sent for cytological evaluation. If a malignancy is diagnosed, it is most likely to be which of the following types?

Question

A 55-year-old woman comes to the office due to a persistent cough, exertional dyspnea, and recent, unintentional weight loss.  She has no chronic medical problems and takes no medication regularly.  She has never smoked and has no history of exposure to industrial pollutants.  She works as an accountant at a large accounting firm.  Vital signs are normal.  Physical examination reveals decreased breath sounds and dullness to percussion at the left lung base.  Imaging studies show an irregular mass in the lower lobe of the left lung and a left pleural effusion.  A diagnostic thoracocentesis is performed and the aspirated fluid is sent for cytological evaluation.  If a malignancy is diagnosed, it is most likely to be which of the following types?

Quizplus · Accepted Answer

11ec160b_3a13_7e46_9249_c16cf0c3f6bf_MD0001_00 This nonsmoking woman with cough and weight loss has a peripheral lung mass with an associated pleural effusion. This presentation is concerning for adenocarcinoma of the lung, the most common lung cancer in the general population, women, and nonsmokers. Although tobacco is the most significant risk factor, the etiology in nonsmokers is thought to be multifactorial. Risk factors include environmental exposures (eg, radon, second-hand smoke) and underlying lung disease. In addition, certain molecular alterations are seen more commonly in nonsmokers; these "driver mutations" are thought be responsible for the development of the malignancy and include epidermal growth factor receptor (EGFR) mutations and ALK gene rearrangements. KRAS mutations, another driver in the formation of adenocarcinoma, is seen more commonly in smokers. Adenocarcinoma typically presents with cough, weight loss, and hemoptysis. Changes to the distal extremities, including clubbing (increased curvature of the nail plate) and hypertrophic osteoarthropathy (proliferation of the bones, skin, and nails of the fingers), may occur and are thought to be due to tumor-derived growth factors. The tumor tends be located peripherally (as in this patient) and may present as a nodule, mass, or obstructive pneumonia. Like all malignancies, metastatic disease to the pleura can cause pleural effusions. (Choice B) Bronchial carcinoid is a rare malignancy that tends to be located centrally, within or adjacent to large bronchi. It typically presents with wheezing due to bronchial obstruction and occasionally also causes carcinoid syndrome (ie, episodic diarrhea, flushing, bronchospasm). (Choice C) Mesothelioma most commonly arises from the mesothelium lining the pleural cavity; tumors are pleural based (ie, pleural mass with associated pleural effusion, pleural thickening), rather than intraparenchymal. In addition, it is extremely rare in nonsmokers with no history of asbestos exposure. (Choice D) Small cell carcinoma is strongly associated with smoking; only 1% of cases occur in nonsmokers. It arises from the basal cells of the bronchial epithelium and displays some neuroendocrine features. Small cell carcinoma usually occurs in major bronchi. (Choice E) Squamous cell carcinoma is also strongly associated with smoking. It usually affects larger bronchi (centrally located) and arises from areas of squamous bronchial metaplasia. Educational objective: Adenocarcinoma is the most common primary lung cancer in the general population, women, and nonsmokers. Epidermal growth factor receptor (EGFR) mutations and ALK gene rearrangements are seen more commonly in nonsmokers and thought to contribute to disease formation in this subgroup. Adenocarcinoma is typically located peripherally and may be associated with clubbing or hypertrophic osteoarthropathy.

A 55-Year-Old Woman Comes to the Office Due to a Persistent