INTRODUCTION: Cavitary degeneration of pulmonary malignancy is well described in the literature. Cystic presentation of malignancy is less common. Here, we present a case of a giant intrathoracic cyst determined to be a de novo presentation of an adenocarcinoma.
CASE PRESENTATION: A 78 year-old Vietnamese man with past history of tuberculosis, and parasitic liver abscess (E. histolytica) presented with complaints of right leg swelling and dry cough. He denied chest pain, fever, or significant dyspnea, but did admit to intermittent streaky hemoptysis. He was a 60 pack-year smoker. There was no significant social, family, occupational, or exposure history. Physical examination revealed an oxygen saturation of 93% on room air with stable vital signs. There was no digital clubbing, cyanosis, or tracheal deviation. The lung fields revealed scant bilateral basal crackles. The right leg was visibly swollen. A venous ultrasound confirmed an above knee deep venous thrombosis in the right leg. A chest film revealed a large multilobulated smooth-edged opacity with mass effect in the left hemithorax. Chest films from ten years previously were reported as normal. Contrast-enhanced computed tomography (CT) of the chest revealed a thin-walled 21 cm by 11cm by 10 cm cystic mass in the medial left hemithorax without associated adenopathy or apparent solid component. Initial diagnostic considerations included congenital cysts, hydatid (ecchinoccal) cyst, intrathoracic pancreatic pseudocyst, cystic tuberculoma, and malignancy. Echinococcal serology was negative. Chest MRI confirmed the cystic nature of the lesion but demonstrated fine septations not seen on CT, suggesting a complex nature to the cyst. Mycobacterial smears and cultures obtained during fiberoptic bronchoscopy were negative. Bronchoscopy was unremarkable aside from a small region of mildly edematous bronchial mucosa located at the orifice to the left upper lobe. Mucosal biopsies taken from this site were consistent with adenocarcinoma. However, given that the appearance of the large cystic mass was atypical for malignancy, cyst aspiration and positron emission tomography (PET) scanning were arranged. PET revealed heterogenous uptake of the entire cystic lesion, as well as focal uptake localized to mediastinal lymph nodes and lumbar spine, suggestive of metastatic disease. Transthoracic fine-needle aspiration of the cyst yielded bloody fluid containing abnormal cells consistent with adenocarcinoma. Post aspiration of the cyst, a previously unidentified solid component was seen and biopsied and showed non-mucinous adenocarcinoma. Several days post aspiration, prior to initiation of treatment, the patient's clinical condition declined and he died.
DISCUSSIONS: This case represents only the third described case in the English literature of non-mucinous pulmonary adenocarcinoma presenting as a cystic chest lesion.1 It is the first case to describe such a large and thin-walled lesion. The two previous cases of cystic adenocarcinoma describe complex cysts with visible septations and walls composed of malignant cells. In the present case, however, the septations were not apparent on contrast-enhanced CT, and the solid component was not appreciated until the cyst had been aspirated. Cystic change is less common than cavitary degeneration but has been described in bronchoalveolar carcinoma, pulmonary mucinous cystadenocarcinoma, chondrosarcoma, and adenocarcinoma. It has been hypothesized that cystic adenocarcinoma may develop if malignant cells extend along the walls of alveoli, permitting cyst formation and enlargement without the more common central necrosis that is often seen in the setting of large pulmonary malignancies.
CONCLUSION: Lung cancer can present de novo as a cystic chest lesion and should be included in the differential diagnosis of even simple appearing cystic chest lesions.
DISCLOSURE: Paul Heffernan, No Financial Disclosure Information; No Product/Research Disclosure Information