A 32-year-old Caucasian woman who was in her usual state of health until approximately 2 months ago was admitted for her new onset of chest pain and shortness of breath. She had a longstanding history of smoking since the age of 9, roughly 2–3 packs per day. Physical examination was within normal limits; no evidence of peripheral adenopathy or cutaneous nodules was noted. A chest x-ray and CT scan revealed a solitary pulmonary mass (Fig. , ). The mass was round and smooth, 2.8 cm in diameter, and centrally located within the left lower lobe.
Chest radiograph showing a mass lesion (arrow) intimately associated with a segmental bronchus of the left lower lobe.
Chest computed tomogram showing localized expansion of mass, which measured 2.8 × 2.0 cm in size.
Additional work-up including abdominal and pelvic CT scans revealed no extra-pulmonary lesions. Because of her significant smoking history, clinical symptoms and imaging studies, a tentative preoperative diagnosis of lung cancer was made. A flexible bronchoscopy was then performed, which revealed no evidence of endobronchial lesions. Subsequently, a lateral thoracotomy was performed. In-situ, the centrally located mass was smooth by palpation and was in close proximity to the pulmonary hilum. There were no visible invasive or metastatic lesions in the adjacent organs or lymph nodes. Four core biopsies were taken from the mass, but no definite pathologic diagnosis of tumor was made on intraoperative frozen section. A diagnostic lobectomy was subsequently performed. The patient had an uneventful postoperative course and was discharged from hospital 4 days postoperatively.
Macroscopically, the tumor was a well-defined solitary mass, measuring 2.8 × 2.0 × 2.0 cm in size. It was located at 2.2 cm from the bronchial margin of resection and 1.5 cm from the over-lining pleural surface. The cut surface of the tumor had a whitish tan appearance and firm consistency. The mass was well-circumscribed but not encapsulated, and did not infiltrate the bronchial wall. The surrounding pulmonary parenchyma had a slightly congested appearance. Six lymph nodes were identified in the peri-bronchial region, the largest measured 1.1 cm in diameter.
Microscopically, the mass was intimately associated with a segmental bronchus and had grown circumferentially along the submucosal and muscular wall. The mass was made of sheets of granular cells. The neoplastic cells displayed moderate atypia, with a marked increase in cellularity and nuclear/cytoplasm (N:C) ratio, greater pleomorphism, nucleolar prominence, identifiable mitotic figures, and prominent spindling of tumor cells (Fig. ). The cytoplasmic granules were PAS-positive and resistant to diastase digestion. Immunohistochemical staining for S-100 protein revealed prominent cytoplasm reaction products in the tumor cells. Staining for vimentin was weakly positive. Tumor cells exhibited increased expression of both p53 and Ki67, with more than 4% and 25% of tumor cells positive for Ki-67 and p53, respectively. The tumor cells did not stain for carcinoembryonic antigen, cytokeratins, epithelial membrane antigen, actin, desmin, myoglobin, smooth muscle actin, CD34, or HMB-45. All six lymph nodes were negative for tumor metastases. The lesion was pathologically diagnosed as a MGCT based on the morphologic findings, results of an immunohistochemical panel, increased p53 expression, and an elevated nuclear proliferative index.
Figure 3 Microscopically, the tumor was made of sheets of granular cells with moderate atypia, prominent spindling, increased nuclear/cytoplasm ratio and greater pleomorphism. Note two giant tumor cells were in the central field of the photograph. (Hematoxylin (more ...)