An Unusual Case of Pleural Effusion as an Initial Presentation of Renal Cell Carcinoma

Abstract

While lung metastasis is common in renal cell carcinoma (RCC), isolated pleural involvement in rare, with only a handful of cases reported[1,2]. This is one such case, only the second case to be reported from the United States. CASE PRESENTATION: A 65-year-old female with coronary artery disease was evaluated in the emergency room with left sided chest pain, shortness of breath and non-productive cough for one week. The pain was non-radiating with no aggravating or relieving factors. She denied fever, chills, palpitations, or sick contacts. She endorsed a 50 pack-year smoking history. She was afebrile, tachycardic, hypertensive and hypoxic upon initial evaluation. Pertinent findings on physical examination include moderate respiratory distress with markedly diminished breath sounds on the left side. A complete blood count revealed neutrophilic leukocytosis (16x10^9/liter). Electrocardiogram and cardiac enzymes were unremarkable. A chest radiograph was notable for a large left sided pleural effusion. A computed tomography (CT) scan of chest demonstrated left pleural effusion, left lung atelectasis, multiple stable pulmonary nodules and an 8 x 8.5 centimeters (cm) lesion with combined solid and cystic elements in the upper pole of right kidney on the last few axial slices. She was treated with supplemental oxygen and empiric antibiotics for suspected bacterial pneumonia. A thoracentesis yielded 1500 milliliters of serosanguinous fluid. Analysis of the pleural fluid revealed papillary clusters of atypical cells with calcification. Upon immunohistochemical staining, these cells were found to be positive for vimentin, cluster of differentiation (CD) 10 and von Hippel Lindau (vHL) gene product. A positron emission tomography scan identified a thick-walled cystic lesion arising from the right kidney as a possible primary lesion. It also revealed multifocal pleural metastases as well as metastatic adenopathy of mediastinum and upper retroperitoneum. A diagnosis of stage IV renal cell carcinoma (Tx, N1, M1) made. She was started on pembrolizumab immunotherapy and is currently on it. DISCUSSION: RCC can present in a number of ways. Classic triad of RCC (flank pain, hematuria and palpable abdominal mass) is rare and usually indicates advanced stages of the disease. Most common metastatic sites include lungs, lymph nodes, bone, liver, and brain. Pulmonary involvement is commonly in the form of parenchymal metastasis. Pleural metastasis is usually secondary to the parenchymal involvement. A study of RCC in 1,451 autopsy cases demonstrated lung parenchymal metastasis in 76% cases and pleural metastasis in 12% cases[3]. However, none of them had isolated pleural metastasis. Isolated pleural involvement is rarely reported. Among such cases, the majority had a pleural tumor in association with the effusion. CONCLUSIONS: This is a case of RCC presenting initially as pleural effusion, without lung metastasis.